基于层序地层模拟的湖岸线迁移对层序定量识别的指示：以鄂尔多斯盆地山2段为例

Quantitative Recognition of Sequence Stratigraphic Units Based on Lacustrine Shoreline Migration Used Sequence Stratigraphic Simulation:Example from the Member 2 of Shanxi Formation,Ordos Basin

湖岸线是水陆沉积的分界线,为探讨其迁移规律与层序间的关系,利用SEDPAK二维层序模拟软件,以鄂尔多斯盆地山2段作为地质原型,对湖岸线迁移进行了定量模拟,进而提出了其可以有效指示层序及内部体系域识别的新认识。对湖岸线迁移规律在水平方向与垂直方向重新进行了划分、定义。在水平方向上,向物源区方向的迁移定义为"正向",对应于湖侵过程;向盆地方向的迁移定义为"负向",对应于湖退过程。"负向"迁移在垂向上可细分为向上方迁移的"同向"迁移和向下方迁移的"反向"迁移,"同向"迁移为正常湖退过程,"反向"迁移为强制湖退过程。湖岸线由"正向"转变为"负向"的分界面为最大洪泛面;反之,为最大湖退面;在"负向"迁移中,由"同向"转变为"反向"的分界面为强制湖退底面;反之,为相对应的整合面。

Lacustrine shoreline is the boundary between the onshore deposits and the subaqueous deposits.This study uses the SEDPAK two-dimensional sequence modeling program to discuss the relationship between the migration and the sequence,member 2 of Shanxi Formation in Ordos Basin as the conceptual geological model.The lacustrine shoreline is redefined and re-classified in horizontal and vertical directions.The landward migration of lacustrine shoreline has been redefined as ＇positive＇,which is equated with the process of transgression.On the contrary,the process of basin-ward migration has been redefined as ＇negative＇,corresponding to the process of regression.In the process of negative movement,the upward migration of the lacustrine shoreline has been redefined as ＇codirectional＇,which is equated with the process of normal regression.In contrast,the process of downward migration has been redefined as ＇reverse＇,corresponding to the process of forced regression.The interface of lacustrine shoreline from positive to negative corresponds to the maximum flooding surface,while the interface corresponds to the maximum regression surface.During the stage of negative movement,the interface of lacustrine shoreline from the codirectional to reverse has been equated with the forced regression bottom surface,whereas the interface is equated with the correlative conformity.