海拉尔盆地乌南凹陷下白垩统沉积充填演化及构造控制

Sedimentary Filling Evolution and Tectonic Control of the Lower Cretaceous of the Wunan Depression in Hailaer Basin

通过层序界面的识别和划分,乌南凹陷下白垩统可划分为5个二级层序,7个三级层序。以断裂坡折带为界,乌南凹陷可划分为西缘陡坡带、东缘斜坡带、乌南次洼带、乌中低凸起、巴彦塔拉断裂带等次级构造单元,各次级构造单元对沉积体系的发育分布具有重要的控制作用。根据沉降史的分析,下白垩统可划分为裂陷初期、裂陷早期、裂陷中期、断-拗转换期和拗陷期5个构造演化阶段,分别发育火山岩-冲积扇盆地层序、冲积扇-浅湖盆地层序、深湖-半深湖盆地层序、半深湖盆地层序和浅湖盆地层序,各二级层序的发育演化和沉积相构成受构造演化的控制。东缘斜坡带和巴彦塔拉断裂带附近是有利储集相带。

According to the recognition and division of the sequence boundaries,the Lower Cretaceous of Wunan depression can be divided into five two-order sequences and seven third-order sequences.Wunan depression is composed of western steep slope zone,eastern gentle slope zone,Wunan sag,Wuzhong uplift and Bayantala fault zone.Each sub-structural unit constrains the development and distribution of sedimentary systems.The tectonic subsidence analysis suggests that the evolution of the Wunan depression can be divided into five stages： early rifting stage,initial rifting stage,intense rifting stage,rifting-subsiding stage and subsiding stage.Alluvial-volcanic basin sequence,alluvial-shallow lacustrine basin sequence,semi-deep lacustrine-deep lacustrine basin sequence,semi-deep lacustrine basin sequence and shallow lacustrine basin sequence are developed respectively.The evolution and sedimentary facies of each two-order sequence was controlled by the different stages.The slope region in the east and the Bayantala fault zone are the favorable reservoir belts.