库车坳陷构造变形层序划分及在油气勘探中的意义

塔里木盆地北部的库车坳陷经过燕山和喜山运动的强烈挤压,并受第三系盐岩蠕变和侏罗系煤层滑脱的控制,形成深、中、浅层截然不同的变形样式和组合,平面展布也有不同特点.本文依变形机制和特点划分出三层构造变形层序:即浅层构造变形层序,以第三系盐岩底界为界面,变形受盐岩蠕变与挤压的联合作用,构造高点的迁移变化较大;中层以第三系盐岩-侏罗系煤层为主体,主要受挤压滑脱控制,构造成带性较好;深层属弱变形层序.中层盐下构造有断层自深部输导油气,且本身构造的完整性与成带性较好,又有盐岩封盖,成藏条件最好,是勘探找油的重点层系.

DIVISION OF STRUCTURAL DEFORMED SEQUENCE IN KUCHE DEPRESSION AND SIGNIFICANCE FOR OIL GAS EXPLORATION

During Yanshan and Himalayan orogeny,various types of deformation and their assemblages in the Kuche depression,which lies in the northern edge of the Tarim Basin,was formed in deep middle and shallow layers and controlled by Tertiary wriggling salt rock and Jurassic sliding coal.These layers styled in distinct deformation,combination and different distributing characteristic in the plane.According to the mechanism and characteristic of the deformation,the structural deformations are classified into three sets of sequences:1 Shallow sequence.Its boundary is the bottom of Tertiary salt rock.The deformation is due to the combined effect of wriggling salt and structure squeezing.The structural highs migrate violently.2.Middle sequence is dominated by the strata between Tertiary salt and Jurassic coal,which is controlled by structure sliding and often forms structural zones.3.Deep sequence is weakly deformed.The middle sequence bellow salt can accumulate hydrocarbon migration through the faults.Besides,it has integrated and belting structures which are sealed by salt rock.It has the most favorable condition for forming reservoir and is the key strata for hydrocarbon exploration.