鄂尔多斯盆地南部上三叠统延长组软沉积变形特征及构造意义

摘要

鄂尔多斯盆地上三叠统延长组发育有多套软沉积变形构造层。经全面细致的钻井岩心与野外露头观察，发现鄂尔多斯盆地南部发育的软沉积变形构造主要有阶梯状小断层、液化砂岩脉（墙）、枕状构造、球枕构造、液化卷曲变形、泥岩撕裂屑等；从长9-长1油层组均有分布，以长7油层组最为发育，这与盆地演化过程中构造活动强弱关系吻合。平面上，整个盆地南部均有分布，但以盆地西南部环县、庆阳、正宁一带最为发育。经对比分析，认为鄂尔多斯盆地软沉积变形构造主要是地震振动触发的，也有部分是在地震、火山活动等所引发的重力流堆积过程中形成的。%Soft sedimentary structures(SSDs)distribute widely in South Ordos Basin.The main types of SSDs are fault-graded faults structure,liquefied sandstone vein structure,pillow structure,ball and pillow structure, vibrational liquefaction curled deformation structure,torn mudstone fragments,which we can observe in out-crops and wells of Yanchang Formation in South Ordos Basin.SSDs distribute from Chang 9 to Chang 1 vertical-ly,and Chang 7 is the most favourable layer of SSDs in Yanchang Formation,which coincides with the strength change of tectonic activity.SSDs can be observed in the whole south of basin,but southwest contributes more. By comparison,seismic is the main trigger of these SSDs,and part of them is built up by mass flow caused by seismic and volcanic eruption.