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    潍北凹陷中新生代层序地层的沉积模式

    Models for Mesozoic sequence stratigraphy of the North Weifang depression

    • 摘要: 潍北凹陷是受郯庐断裂带直接控制而发育起来的一个小型中新生代富含油气沉积盆地。根据地震反射界面特征,在凹陷孔店组和沙四段(沙河街组四段)内鉴别出6个地震层序界面,进而划分为5个三级层序。在分析初始湖泛面和最大湖泛面的基础上,对层序内体系域和沉积特征进行了划分与分析。盆地沉积演化可划分为开裂期,早期沉降,再沉降,早期萎缩和晚期沉降五个阶段,并对凹陷内两种层序地层的沉积模式进行了总结。

       

      Abstract: The North Weifang depression located in northern Weifang, Shandong is a small Mesozoic prolific sedimentary basin confined by the Tancheng-Luxian fault. In terms of the seismic reflection boundaries in the depression, six seismic sequence boundaries or five third-order sequences have been recognized in the Kongdian Formation and the fourth member of the Shahejie Formation. The depression originated in the Eocene has experienced several episodes of evolution from rifting apart (latest Late Cretaceous), early subsidence, resubsidence, early collapse (Oligocene), termination and late subsidence (Neogene to Quaternary). Influenced by the intense faulting of the nearly EW-trending Gucheng-Weihekou fault, the strong subsidence of the northern part of the depression resulted in the formation of the half graben-like depression which is relatively gentle in the northern part while steep in the southern part. Two sedimentary models of sequence stratigraphy are put forward: simple fault and duplex fault.

       

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