济阳坳陷古近系层序界面构建样式、分布特征及其成因动力学分析

受幕式构造运动的控制,济阳坳陷古近系发育多个级次的层序界面,从下到上主要发育Tr、T7、T6'、T6、T4、T2'、T2、T1'、T1等.根据层序界面上下接触组合关系以及层序界面的定义,笔者首次将济阳坳陷古近系层序界面划分为6种成因构建样式:截超型、截平型、平超型、顶超型、平行型和整合型.以地层-岩性圈闭较为发育的T6'和T2'为例,分析了造成层序界面构建样式差异性的动力学因素,认为:断层活动的迁移性与活动时间和活动强度的差异性控制层序界面构建样式的变化;构造沉降中心的迁移性和构造沉降幅度的差异性控制层序界面构建样式的变化.分析这种差异性及其界面动力学变化成因,对于研究济阳坳陷古近系在不同层序界面构建样式上下寻找地层-岩性圈闭具有重要的指导意义.

Construction Styles, Distribution Features and Genetic Dynamics of the Paleogene Sequence Boundaries in Jiyang Depression

Under the control of tectonic episodes,multilevel sequence boundaries were developed from early to late Paleogene in Jiyang Depression,which are called Tr,T7,T6',T6,T4,T2',T2,T1' and T1,respectively.According to the contact relationship of strata and the definition of sequence boundary,the authors have divided for the first time the sequence boundaries into six genetic construction styles,i.e.,the onlap/truncation construction style,the parallel/truncation construction style,the onlap/parallel construction style,the onlap/toplap construction style,the parallel/parallel construction style,and the conformity construction style.In this paper T6'and T2' were taken as examples,below or above which stratigraphic and lithologoic traps are fairly developed.The authors analyzed the dynamic factors responsible for the differences in the construction styles of the sequence boundaries.The results show that there are two genetic dynamics factors controlling the differences of sequence boundaries:one is the migration and the differences of time and intension of fault activities,and the other is the migration of tectonic depocenters and the differences in tectonic subsidence extent.It is very important for geologists to identify stratigraphic and lithologic traps in Jiyang Depression,which are usually controlled by different construction styles of Paleogene sequence boundaries,as evidenced by the analysis of construction style differences and genetic dynamics.