三角洲水道-朵体体系演化机制及沉积模式——基于Doseo盆地东部凹陷白垩系沉积特征物理模拟实验
- 收稿日期:
2024-09-02
- 网络出版日期:
2025-03-04
摘要: 【目的】为了解Doseo盆地东部凹陷白垩系砂体分布规律,拟采用物理沉积模拟方法,设计了一个具备活动底板的水槽实验,以分析研究区水道-朵体体系演化机制,并建立有效的区域沉积模式。【方法】基于前人的朵体发育及演化研究[9-11],通过解析朵体内部结构,划分出多种组成单元,提出了一种新的朵体分类方法。【结果】(1)水道与朵体之间始终存在叠加与被叠加的关系,水道的迁移、演化或消亡均会形成新的朵体;(2)水道-朵体体系中,受水动力强度影响,主要存在三种演化机制,包括原有朵体接受侵蚀改造、砂质沉积为主形成朵体、细粒沉积为主形成泥质薄层;(3)水道属性决定了朵体的发育类型,朵体的形态则受沉积坡度、构造作用、沉积基准面和物源条件等影响;(4)朵体的组成单元、朵体间的接触关系、朵体物性和朵体复合体的类型均会影响砂体连通性,后期水道的演化在一定程度上改善了连通性;(5)Doseo盆地东部凹陷存在深水三角洲和浅水三角洲两种沉积模式:深水三角洲模式中,水道演化区较大,连通性改善较为明显;而浅水三角洲模式中,朵体沉积区较大,朵体平面展布范围广。【结论】新的朵体分类方法及水道-朵体体系演化机制,能够有效应用于研究区砂体连通性分析及沉积模式研究,并有望在未来三角洲沉积模拟实验中得到新的应用。
Evolution Mechanisms and Sedimentary Models of Delta Channel-Lobe Systems: Based on physical simulation experiments of Cretaceous sedimentary features in the eastern depression of the Doseo Basin
- Received Date:
2024-09-02
- Available Online:
2025-03-04
Abstract: [Objective] To understand the distribution patterns of Cretaceous sand bodies in the eastern depression of the Doseo Basin, this study employs physical sedimentation simulation techniques. An experimental setup with a movable baseboard was designed to investigate the evolution mechanisms of the channel-lobe system in the study area and to develop an effective regional sedimentary model, providing theoretical support for future favorable zone predictions. [Methods] Building on previous research on lobe development and evolution and channel classification [17], this study introduces a new classification method for lobes. Lobes are categorized into four types: agglomerative, superimposed, erosional, and amalgamated. Additionally, to accurately describe the development features and evolution of each lobe type, the study further analyzes the internal structures of lobes and identifies various constituent units. [Results and Discussions] (1) A consistent overlapping relationship exists between channels and lobes, where the migration, evolution, or disappearance of channels leads to the formation of new lobes. (2) Within the channel-lobe system, three main evolution mechanisms are driven by hydrodynamic strength: erosion of existing lobes, formation of lobes dominated by sandy deposition, and formation of mud layers dominated by fine-grained deposition. (3) The characteristics of channels determine the type of lobe development, while lobe morphology is influenced by factors such as sedimentary slope, tectonic activity, base level, and sediment source conditions. (4) The connectivity of sand bodies is affected by the constituent units of lobes, their contact relationships, lobe properties, and the types of lobe complexes. Later channel evolution can improve sand body connectivity to some extent. (5) The eastern depression of the Doseo Basin exhibits two sedimentary models: deep-water and shallow-water delta systems. In the deep-water delta model, the channel evolution area is larger, and connectivity improvements are more pronounced. In contrast, the shallow-water delta model features larger lobe deposition areas and wider planar distribution of lobes. [Conclusion] The new lobe classification method and the channel-lobe system evolution mechanism are applicable to the study of sand body connectivity and sedimentary models in the study area, and they are expected to be widely used in future delta sedimentary simulation research.