南堡凹陷第三纪构造作用对层序地层的控制

Tectonic Controls on Sequence Stratigraphy in Tertiary Period in Nanbao Depression

介绍了南堡凹陷的地质背景，研究了构造作用与层序地层的关系结果表明：南堡凹陷的一级构造运动使得从早第三纪到晚第三纪由断陷作用向坳陷作用转化，并分别形成断陷盆地和坳陷盆地,构成两个构造层序.在早第三纪发生的两幕裂陷作用形成了两个亚构造层序,而裂陷幕内的盆缘正断事件形成了三级层序.盆缘正断事件过程中的不均衡沉降造成了沉积体系的变化和迁移.层序地层的构成和沉积体系的变化规律控制了油气生储盖组合特征和分布规律.下第三系作为南堡凹陷的主力含油层系,有利储层主要发育在湖泊扩张早期及湖泊萎缩期,且往往分布在扇三角洲前缘,而湖泊发展鼎盛期是生油岩和盖层发育的有利时期.

Sequence stratigraphy of taphrogenic lake basin was mainly contr ol led by tectonic movement. Multiphase and multiscale taphrogenesis formed sequence stratigraphy. With different scales two tectonic sequences relating to downfau lted basin and depression basin were generated by the firstscale tecton i c movements during Paleogence taphrogenesis to Neogene depression in Nanbao de pression. Two episode riftings during Paleogence formed two subtectonic sequen ces. The normal fault events of rifting episode near basin boundary f ormed the thirdscale se quence. The changing and migrating of depositional systems were owing to the uneven subsidence of boundary normal fault. Sequence stratigraphy and deposit ional systems controlled the assemblages of sourcereservoircap rock and oil/ ga s distribution. Being the main oil/gasbearing beds, the favo rabl e reservoir rocks of Paleogence system distributed in fandelta front were for med during the early stages of expanding and fading stage of lake. While the favorable source rock and cap r ocks were developed during the strongly expanding stage of lake.