渤海盆地及邻区现今构造运动的基本特征

BASIC CHARACTERISTICS OF PRESENT-DAY TECTONIC MOVEMENT IN BOHAI BASIN AND ITS ADJACENT AREAS

摘要根据近十多年来渤海盆地周围地区GPS网的观测资料，分析了这一地区的现今构造运动、内部形变与应变场。渤海盆地及周围地区相对于欧亚板块发生了逆时针旋转，存在一致的SE向运动，速率为2．2—7．2mm／a。该地区的水平形变场是不对称的四象限分布，渤海西区存在比较一致的NE向形变，渤海东北区存在一致的SW向形变，这两个区呈现NE-SW方向的压缩状态；渤海南区存在比较一致的SE向形变，渤海西北区存在比较一致的NW向形变，这两个区呈现NW-SE方向的拉张状态。渤海盆地及周围地区主压应变轴基本上为NEE-SWW方向，主张应变轴基本上为NNW-SSE方向，这与由地球物理学方法得到的该地区的构造应力场主压应变轴的优势方向完全一致。自1969年至今，该区的现今构造应力．应变场的主方向是稳定的。

On the basis of the data obtained from the GPS networks in the Bohai basin and its adjacent areas in the past decade, the present-day tectonic movement, internal deformation and strain field in this region are analyzed. The Bohai basin and its adjacent areas have a counter clockwise rotation related to the Eurasia plate as while a consistent SE ward movement with a velocity of 2.2 -7.2 mm/a. The horizontal deformation field in this region shows an asymmetric four-quadrant distribution. There is relatively consistent NE ward deformation in the western part of Bohai basin and relatively consistent SW ward deformation in the northeastern part, and the two parts are in a NE-SW ward compressive status; there is relatively consistent SE ward deformation in the southern part of Bohai basin and relatively consistent NW ward deformation in the northwestern part, and the two parts are in a NW-SE ward tensile status. In the Bohai basin and its adjacent areas, the principal compressive strain axis is basically in the NEE-SWW direction and the principal tensile strain axis in the NNW-SSE direction, with the dominant direction of principal compressive strain axis of tectonic stress field which are totally consistent in this region obtained with the geophysical method. The principal direction of present-day tectonic stress-strain field in this region has been in stable status since 1969.