南冲绳海槽及其邻域的基底断裂构造

Basement faulted structure in the South Okinawa Trough and vicinity

EW、NEE和NE向基底断裂沿主构造线方向展布，多属张性断裂．基底大断裂宏观上形成和控制了各主构造带的基本构造格架和各具特色的地质构造发育．它们的形成与弧后地慢流上涌和岛弧的旋张掀斜运动而出现的海槽张裂运动密切相关．NW、NNW和NW向基底断裂多属张扭性平移断层．它们对主构造带分割断错，形成和控制了次一级构造区块各具特色的地球物理和地质构造特征．宫古断裂带长期活动，作用十分强烈．它们的形成是由于受来自菲律宾海方向的水平应力作用，地壳作破坏性应力调整的结果．

Babasement faults in EW, NEE and NE direction are situated along outstanding tectonic line, most of which are tensionalfracture. Huge basement faults mainly formed and controlled basic tectonic framework of each main tectonic belt and development of tectonics of different feature. The formation of the basement faults is associated with tensional movement of the OAinawa trough--resulted from rising of the mantle stream of the back-arc and the revolving-tensional tilt of the arc system toward the trench axis. Most of basement faults in NW, NNW and NW direction are tensional strike-slip fault. They cut the main tectonic zone, forming and controlling the different geophysical and tectonic characteristics of the second tectonic blocks. Miyako fracturezone is a very active zone in a long time, which is the result of stress adjustment of crust by the action of horizontal stress from Philippine Sea direction.