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随着页岩油气勘探开发和相关领域研究的不断深入,细粒沉积物的搬运和沉积已成为当前沉积学研究的热点问题之一,但中国中生代湖泊环境中的泥质重力流沉积尚未引起应有的关注。通过岩心观察、薄片鉴定等手段及综合研究,分析了鄂尔多斯盆地晚三叠世湖相泥质重力流沉积特征,探讨了其形成机制与成因分类。鄂尔多斯盆地三叠系延长组湖相泥页岩结构类型多样,发育泥质块体流沉积、泥质碎屑流沉积、泥质浊流沉积和泥质异重流沉积等多种重力流沉积类型。按照泥质含量将重力流划分为砂质重力流、泥质重力流和混合重力流3种亚类,并根据成因将重力流划分为滑塌体、碎屑流、浊流及异重流等4种亚类;结合成因和泥质含量,将重力流沉积共划分为12种类型。滑塌岩、碎屑岩分布于三角洲前缘斜坡脚附近;浊积岩、异重岩广泛分布于三角洲斜坡至沉积中心。认为泥质沉积物可以在强水动力条件下搬运—沉积;重力流沉积细粒物质在湖相沉积中占据很大的比例;泥质重力流对泥页岩中的碎屑物质、黏土矿物及有机质的搬运和沉积起到重要作用,因而对于页岩油气的生烃、储集性能和压裂工艺研究具有重要意义。
With the deepening of research on shale hydrocarbon exploration and development and related fields, the transport and deposition of fine-grained sediments have become one of the hot issues in sedimentology research. However, the gravitational-flow sedimentation in the Mesozoic lake environment in China has not caused Some concern. By means of core observation and thin slice identification and comprehensive study, the sedimentary characteristics of the sediments in the Late Triassic lacustrine facies in the Ordos Basin are analyzed, and their formation mechanism and genesis are discussed. Triassic Yanchang Formation in the Ordos Basin, Hunan Province, Hunan Province, Hunan Province, China The mudstone shales in the Yanghuai Formation are characterized by various types of gravitational flow sedimentation, such as mud flow, sediment deposition, muddy turbidity flow deposition, . The gravitational flow is divided into three subgroups: sandy gravity flow, muddy gravity flow and mixed gravity flow according to the shale content, and the gravity flow is divided into slump body, debris flow, turbidity flow and gravity flow according to the causes 4 kinds of sub-types; combining the cause and the content of shale, the gravity flow sedimentation is divided into 12 types. Collapse rocks and clastic rocks are located near the foot of the front slope of the delta. Turbidites and heno-rocks are widely distributed in the delta slope to the sedimentary center. It is considered that muddy sediment can be transported-deposited under strong hydrodynamic conditions, gravitational-flow sedimentary fine-grained matter occupies a large proportion in the lacustrine sedimentation, and muddy gravity flow can affect the detrital material, clay minerals, The transport and deposition of organic matter play an important role, which is of great significance to the research on hydrocarbon generation, reservoir property and fracturing of shale oil and gas.