关于阿尔金北缘活动断裂带运动方式的转变机制的讨论

通过对构造变形、构造空间展布关系、断面产状变化以及构造应力场等的综合分析研究认为，阿尔金北缘活动断裂带在第四纪内的运动方式经历了由挤压逆掩为主（早更新世—中更新世初期）到左旋走滑兼具挤压逆冲（中更新世中、晚期）直至纯左旋走滑运动（晚更新世—现今）的逐渐转变过程．作用于这种转变，研究区内区域构造应力场的演变大致可以划分为三期，其主压应力轴方向由老至新依次为近南北向、北北东向和北东向．构造应力场和断裂带运动方式的这些变化主要是由于印度板块持续向北推挤导致青藏高原内部次级块体向东滑动、岩石圈物质向东流展而造成的．

DISCUSSION ON CHANGE AND ITS MECHANISM OF MOVEMENT FORMS OF THE ACTIVE FAULT ZONE ALONG NORTH MARGIN OF MT. ALTUN

Based on the comprehensive analysis of tectonic deformation,tectonically spatial distribution relation,fault plane occurrence change,tectonic stress field,etc.,it is considered that the Quaternary movement forms of the active fault zone along north margin of Mt.Altun underwent a gradual change process from compressional thrust through left-lateral strike-slip simultaneously with compressional thrust to pure left-lateral strike slip.Acting upon the change,evolution of regional tectonic stress field in the studied area is roughly divided into three stages during which the directions of compressive principal stress axes are near NS, NNE and NE in the order from the earlier to the later.The changes of tectonic stress field and fault movement form mainly are caused by the eastward slip of secondary block and eastward flow of lithospheric mass resulting from continuously northward push and pressure of the Indian plate.