塑性岩体与逆冲构造变形关系讨论——库车坳陷西部实例分析

在冲断构造分析过程中 ,常常把塑性岩体仅仅作为滑脱层看待 ,忽略了一些地区塑性变形与冲断构造变形的复合作用。根据露头、钻井、地震等资料 ,应用平衡剖面等技术对库车坳陷西部的构造变形进行了恢复分析 ,发现库车坳陷西部的下第三系盐、膏、泥等塑性体受重力和构造应力联合作用发生了复杂的变形。以往单纯用冲断构造模式分析其成因机制 ,没能科学地反映中生界与新生界之间的变形缩短量的差异 ,通过塑性体的底辟变形和滑脱变形依存关系的剖析 ,能够恢复库车坳陷西部构造演化过程 ,进而为油气勘探提供指导。

A DISCUSSION ON THE RELATIONSHIP BETWEEN PLASTIC BODY AND DEFORMATION OF THRUST STRUCTURE--IN WESTERN KUCHE DEPRESSION OF CHINA AS AN EXAMPLE

The plastic body is usually looked upon as a slip fault surface in the theoretical analysis of the thrust structure, thus the compound action of plastic deformation and thrust deformation are ignored in the same region. Based on data from geologic outcrop, seismic profile and drilling-log, we have conducted an analysis of structure deformation by using balanced-section technique. The analysis suggested that the plastic bodies, such as salt, gypsum and mud in Neogene in Western Kuche Depression, are complexly deformed by joint action of gravity and structural stress. Simply analyzing their producing mechanism by using thrust-related folding structural pattern as before could not scientifically reflect the discrepancy of the shortening of Mesozoic and Cenozoic. Synthetically analyzing the plastic bodies can help us in structural pattern study of Western Kuche Depression and provide guide and suggestion on oil-gas prospecting.