Abstract:

Considering the triple-nonlinear character of continental tectonic deformation,the large de-formation in eastern Xizang area caused by continental collision between India and Eurasia is stud-ied by means of dynamic FEM. The results of numerical simulation show a sharp longitudinalcontractive defOrmation;most of principal strain axes have a tendency to rotate clockwise;but lat-eral displacement seems not remarkable. The maximum lateral displacement is between Hongheand Xianshuihe faults, the Sichuan-Yunnan rhombic block can move in SE direction.Honghe、xi-anshuihe、Kunlun and Altun fatilts rotate clockwise during collision. The slip along Honghe faultis sinistral in initial 8tage and dextral in lflter stage,but the slip along other three faults is sinistralall the time. Generally,the deformation caused by continental collision can be divided into sevenregions:a)the front edge region,Uthe horned region,c)the pulled region,d)the due front region,e)the oblique front region,f)the ahead flank region,and g)the flank region.

Key words: Finite element modeling, Plate collison, India, Eurasia, Tectonic deforma-tion, Triple-nonlinearity

摘要：

在全面考虑了大陆构造变形三重非线性特征的基础上,用动态有限元法研究了藏东对印度与欧亚大陆碰撞作用的大变形响应。数值模拟结果显示了明显的纵向收缩变形,变形主轴多具有顺时针转动的趋势,但横向位移在总体上并不显着。其最大值正位于红河和鲜水河断裂之间,这一结果论证了印度板块对欧亚大陆的碰撞可能是川滇菱形块体向南东运动的动力来源。红河、鲜水河、昆仑及阿尔金活断层在碰撞作用下发生了顺时针的旋转变形;而且,计算结果模拟出了红河断裂由左旋变为右旋,另3条断裂始终左旋的运动特征。

关键词: 有限元模拟, 板块碰撞, 印度, 欧亚大陆, 构造变形, 三重非线性