鄂尔多斯盆地中生代构造活动响应特征

鄂尔多斯盆地现今的构造特征与古生代的构造面貌具有较大的差异,其构造的主要变革期发生于中生代。本文通过对各时期古构造特征的详细编图分析,厘定了二叠纪末期石千峰组沉积时期是构造格局发生变化的初始阶段,古生代的构造格局以南北向构造线为主体,中生代的构造格局以东西向的构造线为主体。同时,盆地内以及周缘造山带的岩浆活动、二叠系石千峰组的油气成藏时间都与这一主要构造变革期息息相关。盆地西南部龙门构造的岩浆活动时间与秦岭造山带、阴山造山带的岩浆活动时间基本一致,受南北向构造应力的作用;盆地东部紫金山岩浆体的活动时间与西部贺兰山鼓鼓台岩浆体的活动时间基本一致,主要受东西向构造应力的作用,二者对应的时间分别为印支期和燕山期。石千峰组中的包裹体均一温度峰值为160℃,相当于白垩纪末期,正是由于强烈的构造运动致使下部的原生油气藏遭受破坏,沿着断裂带而发生重新的运移聚集,进而形成了次生油气藏。

Response Characteristics Of Tectonic Activity In Mesozoic Of Ordos Basin

The structural characteristics have major difference between paleo tectonic and present tectonic in Ordos basin,Mesozoic is major tectonic revolution term.Through the paleo tectonic maps of different terms,the initial stage of tectonic revolution is Shiqianfeng period of the permian,the direction of tectonic line is north-south trending in paleozoic,the direction of tectonic line is east-west trending in Mesozoic.In the meantime,the magmatic activity of basin and orogenic belt,the oil and gas reservoir formation of Shiqianfeng formation,all are relative with major tectonic revolution term.In the south,the magmatic activity time of Longmen structural is the same with qinling orogenic belt and Yinshan orogenic belt,controlled by the Stress Field of north-south trending;the magmatic activity time of Zijinshan in the east is the same with Helanshan magmatic body in the west,controlled by the Stress Field of east-west trending,the former happened on indo-chinese epoch,the latter happened on Yanshan epoch.The homogenization temperature of fluid inclusions in the Shiqianfeng formation is 160℃,the time is equivalent to the latest cretaceous,due to intensive tectonic movement,the primary oil and gas reservoirs are destroyed,oil and gas moved along the fault belt,secondary oil and gas reservoirs are formed.