陆相细粒混合沉积分类、特征及发育模式——以东营凹陷为例

Classification, characteristics and development models of continental fine-grained mixed sedimentation: a case study of Dongying sag

细粒混合沉积是近年来的研究热点,目前对其研究还不够系统和深入。基于持续多年对东部陆相页岩的研究,重新定义了细粒混合沉积概念,综合钻井、录井、测井、岩心、薄片和X射线衍射分析等资料,按照岩相发育特征、砂/灰/泥比值、混积组构方式和沉积微相分带4项分类原则,提出陆相细粒混合沉积扇形分类方案,将细粒混合沉积划分为灰-泥二元混积、砂-泥二元混积和砂-灰-泥三元混积3种类型,并进一步细分为12个亚类。在此基础上,以东营凹陷为例,从点、线、面3个维度分析了陆相细粒混合沉积的发育特征和展布规律,提出细粒混积相带分布模式,认为细粒混积在平面上具有环带分布特征。并进一步分析了细粒沉积中的天文节律特征,认为其可以很好地反映细粒混合沉积中的旋回特征,对于混合沉积精细研究具有借鉴意义。

Fine-grained mixed sedimentation has been a research hotspot in recent years,and it requires systematic and deep research.Based on studying the eastern continental shale for many years,this paper redefines the concept of fine-grained mixed sedimentation.Based on the integrated data involving drilling,logging,mud logging,core,thin section and X-ray diffraction analysis,according to the four classification principles including development characteristics of lithofacies,sandstone/limestone/mud ratio,fabric mode of mixed sedimentation and sedimentary microfacies zoning,this paper proposes a new fan-shaped classification scheme for continental fine-grained mixed sedimentation,divides the fine-grained mixed sedimentation into limestone-shale binary mixed sedimentation,sandstone-shale binary mixed sedimentation and sandstone-limestone-shale ternary mixed sedimentation,and further subdivides them into 12 subcategories.On this basis,taking the Dongying sag as an example,this paper analyzes the development characteristics and distribution laws of continental fine-grained mixed sedimentation from the perspective of point,line and surface,puts forward a distribution model of fine-grained mixed sedimentation facies belts,and holds that the fine-grained mixed sedimentation has the characteristics of zonal distribution on the horizontal level.Furthermore,it analyzes the characteristics of astronomical rhythm of fine-grained sediments,and points out that they can well reflect the cycle characteristics of fine-grained mixed sediments,which has reference significance for the fine research of mixed sedimentation.