广角反射/折射地震探测揭示的冲绳海槽地壳结构

广角反射/折射地震探测是研究冲绳海槽地壳结构与性质的有效方法。通过收集整理冲绳海槽及邻区广角反射/折射地震研究成果，对冲绳海槽地壳结构性质进行了探讨。结果表明，冲绳海槽地壳厚度较薄，绝大部分地区属于减薄的陆壳，但局部已出现洋壳；海槽北、中、南三段处于不同的构造演化阶段，地壳厚度、结构、减薄方式等存在较大差异；琉球俯冲带不同分段活动特征及构造应力场的不同是造成冲绳海槽地壳结构性质和构造演化南北差异的主要原因；冲绳海槽内洋壳局限于海槽中、南段轴部，在轴部地堑沿走向方向布设OBS测线将有助于进一步确定洋壳的存在。

CRUSTAL STRUCTURE OF THE OKINAWA TROUGH: EVIDENCE FROM WIDE-ANGLE REFLECTION AND SEISMIC REFRACTION SURVEYS

Seismic refraction/wide-angle reflection survey is used in this paper to ascertain the crustal structure of the Okinawa Trough. The seismic refraction/wide-angle reflection survey data shows that the Okinawa Trough has a thin crust, of which the major part is a thinned continental crust. However, the existance of oceanic crust in some local areas cannot be excluded. The northern, middle and southern parts of the Okinawa Trough are in different stages of tectonic evolution with different crustal thicknesses, structures and thinning forms. All of the differences of the Okinawa Trough from north to south are closely related to the variation in the kinematics and dynamics of the Ryukyu subduction zone. The newborn oceanic crusts will be confined in the narrow axial part of the Trough if exist. In this regard, longitudinal OBS profiles are recommended being used in the axial grabens. It would be helpful in determination of the existence of the newborn oceanic crust.