Abstract This paper analyzes the sedimentology and lithofacies of the lacustrine shale from the third member of the Eocene Shahejie Formation (Es3) in the Dongpu sag, Bohai bay basin, eastern China. The results show that lacustrine shale is heterogeneous in its sedimentary structure, lithology, mineralogy, lithofacies, and oil content. From the margin of the lake to its center, the depositional environment progresses from delta front to prodelta to deep water lake, and the primary sedimentary lithologies changes from interbedded mudstone and sandstone to mudstone with siltstone to mudstone with evaporite and carbonate rocks. The major deep water deposits are laminated shales. From the lake margin to the center, felsic mineral content decreases gradually, and clay mineral and pyrite content increases gradually. Felsic mineral content is the highest in the delta front shale, and clay mineral and pyrite content is highest in the deep water lake. Shale lithofacies also change with the depositional environment. The lithofacies of the delta front shale are primarily felsic-rich lithofacies: clay-rich carbonate-poor felsic shale (S-4) and a clay-rich, carbonate-poor felsic-rich mixed shale (MS-2). The lithofacies of the prodelta shale are primarily a carbonate-poor felsic-rich muddy shale (M-2), S-4, and MS-2. The lithofacies of deep water lake shales are primarily clay mineral-rich lithofacies: M-2, MS-2, and the clay-rich, carbonate-rich, felsic-rich mixed shale (MS-3). The TOC and the types of organic matter also change with the depositional environment in the Dongpu sag. The results of this study show the sedimentary structures, lithology, mineral content, lithofacies, and spatial distribution of the lacustrine shale was not only controlled by the macro depositional environment and the local depositional environment, but also controlled by the source and transport (or the sediment transport path), water depth, and accommodation space.

中文翻译：

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湖相页岩沉积与岩相——以渤海湾盆地东埔凹陷为例

摘要 对渤海湾盆地东埔凹陷始新世沙河街组三段(Es3)湖相页岩沉积学和岩相进行了分析。结果表明，湖相页岩在沉积结构、岩性、矿物学、岩相和含油量方面具有非均质性。从湖缘到湖心，沉积环境由三角洲前缘到前三角洲再到深水湖，原生沉积岩性由泥岩与砂岩互层转变为含粉砂岩的泥岩，再到含蒸发岩和碳酸盐岩的泥岩。主要的深水矿床是层状页岩。从湖缘到中心，长英质矿物含量逐渐减少，粘土矿物和黄铁矿含量逐渐增加。三角洲前缘页岩长英质矿物含量最高，深水湖中粘土矿物和黄铁矿含量最高。页岩岩相也随着沉积环境的变化而变化。三角洲前缘页岩的岩相主要是富长英质岩相：富粘土碳酸盐贫长英质页岩（S-4）和富粘土贫碳酸盐富长英质页岩（MS-2）。前三角洲页岩的岩相主要是贫碳酸盐富英质泥质页岩 (M-2)、S-4 和 MS-2。深水湖页岩的岩相主要是富含粘土矿物的岩相：M-2、MS-2，以及富含粘土、富含碳酸盐、富含长英质的混合页岩（MS-3）。东埔凹陷TOC和有机质类型也随着沉积环境的变化而变化。本研究结果显示了沉积构造、岩性、矿物含量、