沾化凹陷下第三系不整合类型及其地质意义

UNCONFORMITY TYPES OF THE LOWER TERTIARY AND THEIR GEOLOGICAL SIGNIFICANCE IN ZHANHUA TROUGH

渤海湾盆地沾化凹陷下第三系中发育一系列不整合面 ,分隔了不同级别的地层单元 ,地层记录出现了间断。虽然对间断历史的推测十分困难 ,但这些不同级别、样式与分布的不整合面组成的系列时空型式不仅为各地层单元形成限定了边界约束 ,而且为整个凹陷的盆地动力学分析提供了时空框架和动力学信息。沾化凹陷的不整合成因类型包括基底不整合、裂陷幕不整合、破裂不整合和与构造活动、水位变化、沉积过程及气候变迁相联系的不整合或沉积间断。综合性的不整合研究不仅可以用于盆地动力学研究 ,也是石油勘探寻找油气圈闭的有效手段。

A series of unconformity surfaces occurred in the lower Tertiary in Zhanhua trough, Bohaiwan basin. The boundaries of stratigraphic units with different ranks imply breaks of stratigraphic records. Although it is difficult to speculate the history of break, those unconformity surfaces with different ranks, different types and different distributions which constructed a series of occurrence styles in stratigraphy, not only confined the stratigraphic units but also provided or revealed a time-space framework for the dynamic analysis of basin formation. The original types of unconformity surface of Zhanhua trough include unconformity of basement, unconformity of episodic rifting and unconformity of break, as well as the unconformity or break related to tectonic movement, water level change, sedimentary process and climate change. A synthetical study on the unconformities can be useful for the basin dynamic analysis, and will be an effective way in oil exploration for oil traps also.