冲绳海槽及其邻域地球物理场与地壳结构特征

Character of geophysical field and crustal structure of Okinawa Trough and adjacent region

分析了冲绳海槽及其邻域的重、磁场特征 ,同时对研究区域的布格重力数据进行了上延拓及二次垂直导数计算 .根据分析与计算可知 ,在冲绳海槽及其周边区域 ,重磁异常的主要走向为NNE向 ,重、磁场的分布特征表明冲绳海槽及邻域地球物理场变化复杂 ,变化幅度大 .参考地震解释结果 ,利用重力资料 ,应用调和级数法对研究区的莫霍界面进行了反演计算 ,得到了该地区莫霍界面深度分布 ,计算表明冲绳海槽及邻域地区莫霍界面深度在 2 8～ 4km之间变化 ,地壳厚度自西向东逐渐减薄 ,显示出陆壳—过渡壳—洋壳的转变过程 .

This paper analyzed characters of gravity and magnetic fields of Okinawa Trough and adjacent region. Upward 20km and second vertical derivative of Bouguer gravity anomalies of study area were calculated. According to analyzing and calculating, the direction of gravity and magnetic fields is NNE. Distributing characters of gravity and magnetic fields indicated that geophysical fields changed complexity and had great range. Refer to results of seismic survey made in study area and using gravity data, we computed crustal thickness of the study area. The result indicated that crustal thickness of the study area is from 28～4 km. Crustal thickness of study area decreased thin from west to east. It is shown that character of crust of study area changed from continental to transitional then to oceanic crust.