摘要
东濮凹陷是渤海湾盆地的一个次级构造单元 ,其古近系的两个沉积旋回发育了四套盐岩 ,分别位于沙河街组第三段的第四亚段 (S43)、第三亚段(S33)、第二亚段 (S23)和沙河街组的第一段 (S1 ) ,主要分布在凹陷北部。每套盐岩又由若干个盐韵律组成 ,每一单韵律由盐岩和泥岩组成。两套等时对比标志层 (深湖沉积 )之间盐岩与砂泥岩存在着相变关系。盐岩是在深盆背景下干旱成因的 ,盐类物质来自地下深处上涌的卤水 ,卤水在凹陷中的分层作用是盐岩形成的主要方式 ,卤水上涌通道是基底大断裂系 ,其动力来源是岩浆活动。盐岩的阻隔作用使其对下部地层的温度、压力的变化均有影响 ,这种影响有利于加快盐岩下地层中的有机质成熟与演化。盐岩又是良好的盖层 ,且在高温、高压下盐岩呈塑性状态。勘探实践看出东濮凹陷的岩性油气藏与盐岩的沉积有密切的关系 ,因此搞清盐岩的分布规律对东濮凹陷下步勘探有着极为重要的意义。
The Dongpu Sag is a sub-tectonic unit of the Bohai Bay Basin. In the Sag, four sets of salt rock developed in two depositional cycles of the Paleogene, which occurred respectively in the Fourth Submember(S4 3),Third Submember(S3 3) and Second Submember(S2 3) of Member Ⅲ(S 3) and Member I of the Shahejie Formation(S 1). They are mainly distributed in the north part of the Dongpu Sag.Every set of salt rock contains many salt rhythms, and each rhythm is composed of salt rock bed and mudstone bed. Laterally, salts grade into mudstones and sandstones. The salt rock is formed in deep basin in arid climate. The salt material is derived from the uprising brine from deep underground. Layered of brine is the basic form for the formation of salt rock. The upwelling path of the brine follows large basement faults. Magmatism provides the dynamic force for brine uprising.The change of temperature and pressure beneath should be affected by the insulation of salt layers, and this will quicken the maturation and evolution of organic matter. Salt rock is excellent caprock, which is plastic under high temperature and pressure. Previous exploration showed that the lithologic reservoir is closely related with salt deposition. So for further exploration, it is very important to understand the distribution laws of the salt rock in the Dongpu Sag.
出处
《古地理学报》
CAS
CSCD
2003年第2期162-170,共9页
Journal of Palaeogeography：Chinese Edition
关键词
河南
东濮凹陷
古近系
沙河街组
沉积旋回
盐岩
成因
沉积特征
salt rock,sedimentary characteristics,depositional cycles,Shahejie Formation, origin,Dongpu Sag
