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利用物理模拟实验,建立了两个不同边界条件的模型分别模拟帕米尔突刺东缘柯克亚-和田褶皱冲断带和喀什-叶城转换断层带的逆冲走滑构造演化过程,进而分析和讨论了研究区构造变形特征和变形机制。物理模拟实验结果表明:(1)帕米尔突刺东缘的柯克亚-和田褶皱冲断带和喀什-叶城转换断层带均形成于压扭应力场作用下,发育明显断层走滑现象,前者逆冲前缘断层兼具左行走滑特征,后者逆冲前缘断层则具右行走滑特征,但前者总体走滑量明显小于后者;(2)帕米尔突刺东缘的柯克亚-和田褶皱冲断带和喀什-叶城转换断层带走滑作用均主要位于山前边界断层带,越靠近逆冲前缘(盆地内部),走滑效应越微弱,挤压效应越明显;(3)在边界走滑断层前缘(往盆地方向),弧形断裂由挤压方向向前依次产生,并且斜向相交,验证了帕米尔东缘冲断带构造演化符合自南向北依次变新的规律;(4)在斜向压扭作用过程中,走滑断层构造带不一定发育明显的高角度甚至直立的断层,也可能表现为逆冲叠瓦构造楔样式,形成走滑逆断层,故在进行帕米尔突刺东缘(如塔西南山前)地震剖面构造解析时应充分关注这种构造类型。
Using physical simulation experiments, two models of different boundary conditions were established to simulate the thrust-strike-slip tectonic evolution of the Kekeya-Wada fold belt and the Kashi-Yecheng transitional fault belt on the eastern margin of the Pamir spikes respectively. The tectonic deformation characteristics and deformation mechanism in the study area are discussed. The physical simulation results show that: (1) Both the Kekeya-Wada fold thrust belt and the Kashgar-Yecheng transitional fault belt in the eastern margin of the Pamir spike develop under the effect of compressive-torsional stress field and develop obvious fault strike-slip phenomenon. The former The thrust front fault has both left-lateral strike slip features, while the latter thrust front fault has a right-lateral strike slip feature, but the overall strike slip of the former is obviously smaller than the latter. (2) The Hetian fold-thrust belt and Kashi-Yecheng transitional fault zone strike-slip are mainly located in the front piedmont fault zone. The closer to the front of the thrust (the interior of the basin), the weaker the strike slip effect and the more obvious the squeezing effect. (3) ) Strike the front of the strike-slip fault (toward the basin) along the boundary. The arc-shaped faults are generated in turn by the extrusion direction and intersect obliquely, which verifies that the tectonic evolution of the thrust belt in the eastern Pamir conforms to the change from south to north (4) During the process of diagonal compression, the strike-slip fault zone may not develop obvious high-angle and even upright faults, but may also be characterized by thrust wedge-slip wedge pattern, forming strike-slip thrust faults, So in the eastern edge of the Pamir spur (such as the pylon front pylon) seismic section structure analysis Pay full attention to this type of construction.