台湾弧前盆地构造反转的数值模拟

NUMERICAL SIMULATION OF THRUST STRUCTURAL INVERSION FOR TAIWAN FORE-ARC BASIN

台湾造山带是世界上最年轻的活跃的造山带之一,位于欧亚板块和菲律宾海板块的交界处,具有独特的地质环境。海岸山脉位于台湾岛的最东侧,由残留的弧前盆地和火山岛弧组成,前者为北吕宋海槽弧前盆地经两期强烈的挤压剪切构造演化而来。利用FLAC6.0软件模拟了台湾弧前盆地逆冲构造反转的演化过程。通过模拟结果分析发现,台湾弧前盆地中逆冲构造的反转是由东向西逐渐发育而来,由局部向西倾斜的次级褶皱构造最终演化为整体向西的逆冲构造。地层厚度和岛弧基底的坡角对于褶皱的形成演化方式都起到了明显的控制作用。

The Taiwan orogenic belt,located in the juncture of the Eurasian plate and the Philippine Sea plate,is one of the youngest active orogenic belts in the world within a unique geological environment.The Coastal Mountains,which is located in the east of the Island,are composed of a residual fore-arc basin and a volcanic island,and the former of which is evolved from the fore-arc basin of the north Luzon Trough after two-stages of strong extrusion of shearing structure.This paper adopts FLAC6.0to simulate the thrust structural inversion of the Taiwan fore-arc basin.It is found out through analysis of simulation results that the reversal of thrust structure in the Taiwan fore-arc basin is developed from east to west gradually,and evolves from local tectonic inversion in the beginning to overall thrust structure westward finally.In addition,stratum thickness and slope angle of basement plays certain control roles in the formation and evolution of folding.