富有机黏土复合体湖盆深水细粒重力流沉积机制研究—以鄂尔多斯盆地三叠系延长组为例

湖盆深水细粒重力流沉积机制是国际沉积学界研究的热点和难点问题。细粒沉积物富含黏土矿物和有机质，黏土吸附有机质形成的有机黏土复合体对细粒重力流搬运演化过程的控制作用尚不明确。鄂尔多斯盆地三叠系延长组长7段深水细粒重力流沉积物富含黏土矿物与有机质，且混合事件层、过渡流体沉积发育，是探究细粒重力流沉积机制的绝佳场所。项目拟开展岩相和岩相组合类型划分，分析岩相组合侧向演化构成的相域类型，基于相域类型和沉积动力关系分析，明确细粒重力流沉积物成因；在相域类型框架内，分析重力流不同演化阶段岩相组合、沉积单元物质组成与沉积动力的相关关系，开展有机黏土复合体控制的细粒重力流搬运演化过程水槽模拟实验研究，阐明细粒重力流沉积机制；探讨细粒重力流沉积分布控制因素和分布规律，结合岩相组合类型与有机黏土复合体发育关系，明确有机质富集规律。研究成果可望丰富和完善细粒沉积学理论体系，并为细粒非常规油气勘探开发提供新思路。

The depositional mechanisms of deep-water fine-grained gravity-flow sediments in lacustrine basin are a hotspot and difficult problem of sedimentology internationally. The fine-grained sediment contains abundant organic materials and clay minerals. The adsorption of organic materials by clay minerals will form organo-clay complex. However, the transport and evolution processes of fine-grained gravity-flow with the effect of organo-clay complex are not clear until now. Deep-water fine-grained gravity-flow sediments of the Chang7 Member of Triassic Yanchang Formation in the Ordos Basin are rich in clay minerals and organic materials. In addition, hybrid event bed and transitions flow deposits are common, which made it an ideal place to analyze the depostional mechanisms of fine-grained gravity-flow. The lithofacies and lithofacies association will divide first. The facies tracts are then determined by the lateral variation of lithofacies association. The origin of deep-water fine-grained gravity-flow sediments will reveal based on facies tracts and sediment dynamics analysis. The relationship between sediment dynamics and composition of sediment unit in different lithofacies associations of different evolution processes are analysis under the facies tracts frame. Then, flume tank simulation experiments are designed to analyze the control of organo-clay complexes on the formation and evolution processes of fine-grained gravity-flow sediments. The formation mechanisms of fine-grained gravity-flow sediments will be clarified. The distribution pattern and the control factors of fine-grained gravity-flow sediments will be discussed. Based on relationships between types of lithofacies association and content of organo-clay complexes, we will reveal the enrichment of organic matter of fine-grained gravity-flow sediments. Research results can deepen and perfect the understanding of theories of fine-grained sedimentology. At the same time, it may provide new ideas for fine-grained unconventional oil and gas exploration and development.