鄂尔多斯盆地东南部延长组古地震效应及其地质启迪

Effect of Ancient Earthquake and Its Geological Significance of Upper Triassic Yanchang Formation in Southeast Ordos Basin

印支期秦岭造山活动控制和影响着鄂尔多斯盆地南缘边界性质和盆内延长组的沉积作用。通过岩芯分析,在盆地东南部延长组地层中识别出震裂缝、层内阶梯状微断层、微褶皱、液化砂岩脉、液化卷曲变形、球-枕构造、环状层理、丘-槽构造、震积角砾岩等典型的软沉积物变形构造,反映该时期研究区有受频繁且强烈地震作用事件影响的痕迹。在此基础上,对晚三叠世鄂尔多斯盆地盆山耦合作用过程及其响应的动力学机制进行了深入分析;进一步详细研究了震浊积岩这一特殊事件沉积体的形成机制与时空分布规律,并建立其沉积模式;最终讨论了该时期地震作用事件的属性特征及周期活跃性。

Qinling orogenic movements in Indo-sinian epoch control and impact the southern boundary nature and the sediment of the Upper Triassic Yanchang Formation in Ordos Basin.Through analysis of cores,such typical soft sedimentary deformation structures were identified from the Yanchang Formation in southeastern Ordos Basin as earthquake rimas,ladder-shaped faults,micro folds,liquefied sandstone veins,vibrational liquefaction curled deformation structures,ball-and-pillows,loop beddings,colliculus-groove structures,earthquake breccias,which reflected that there were intense and frequent earthquakes during the period in study area.On the base of the above analysis,deeply analyzing the dynamic mechanism of basin—mountain coupling action process and responses in Late Triassic Ordos Basin,and further studying on the special formation mechanism,spatial and temporal distribution of seismo-turbidites which were event deposits in detail,consequently,sedimentary model of seismo-turbidites have been established.Finally,the attribute character and active period of seismic events in Late Triassic Ordos Basin are discussed.