川西两期前陆盆地南北两段构造演化的地球物理特征

区域构造演化研究结果表明,川西前陆盆地经历了早中生代和晚新生代两期前陆盆地演化过程。无论是前陆盆地的发育程度还是前陆变形特征及前渊带沉积作用,盆地的南、北两段都存在明显的差异。根据川西地区及邻区的重磁场特征,获得了川西地区基底性质及主要断裂带分布的研究成果。德阳-绵阳一带刚性基底对新生代变形由南向北的传播起了阻挡作用,奠定了新生代变形南强北弱的格局。同时,一系列北西向走滑断裂带的存在进一步削弱了新生代变形作用。基底性质的差异和北西向走滑断裂带的存在是造成川西前陆盆地南、北两段差异的主要制约因素,直接造成了南、北两段新生代变形的差异。

Geophysical evidences of two-segment tectonic evolution of two-phase foreland basin in the western Sichuan province

The studies on the regional tectonic evolution of foreland basin in the western Sichuan province showed that this basin underwent two epochs of tectonic evolution in the Early Mesozoic and Later Cenozoic respectively. The development of foreland basin,deformation characteristics of the foreland and the sedimentation of foredeep in the south and north parts of this foreland basin are all different distinctly. The gravity and magnetic data of the western Sichuan province and its adjacent areas were analyzed. Some new results of distribution and the basement features in the main fault zones were obtained. The rigid basement near Deyang-Mianyang area blocked the propagation of the Cenozoic deformation from south to north, and a series of northwest strike-slip faults further depressed the Cenozoic deformation. The difference of basement features and the existence of a series of northwest strike-slip faults resulted in the difference of the Cenozoic deformation between the north and the south parts.