Seven mudstone/shale core samples were collected from the first member of the Shahejie Formation (E₂s¹) in this study, which is considered as a potential source rock in the Liaodong Bay subbasin. The biological sources and sedimentary environments of the E₂s¹ source rocks were studied based on the analyses of organic geochemistry and organic petrology. The results indicate that E₂s¹ source rocks were deposited in a lacustrine environment with relatively high salinity, which caused the stratification of water body and anoxic bottom conditions. The abundant and stable presence of regular steranes, dinosteranes, 4α-methyl-24-ethylcholestanes, 24-norcholestanes, 24-n-propylcholestanes, hopanes, 2α-methylhopanes, and 3β-methylhopanes in the studied samples indicate that dinoflagellates, diatoms, pelagophyceae, cyanobacteria, rhizobiales and aerobic methanotrophs were the main biological sources of the E₂s¹. Among them, dinoflagellates are closely related to the formation of organic-rich E₂s¹ source rocks, which is supported by the positive correlation between TOC or HIvalues and 4α-methyl-24-ethylcholestane (biomarker of dinoflagellates) contents. Trace amounts of terrestrial higher plant biomarkers in the studied samples indicated that their contributions to organic matter were limited. This is consistent with the abundance of lamalginite and mineral-bituminous groundmasses observed in the E₂s¹ samples under optical micrographs. Widely occurring marine incursion events in the Eocene in the Bohai Bay Basin may have also occurred during the deposition of the E₂s¹ in the Liaodong Bay subbasin, supported by the presence of a typical marine pelagophyceae biomarker (24-n-propylcholestane).

本研究从被认为是辽东湾次盆地潜在烃源岩的沙河街组一段（E ₂ s ¹ ）采集了7个泥岩/页岩岩心样品。在有机地球化学和有机岩石学分析的基础上，研究了E ₂ s ¹烃源岩的生物来源和沉积环境。结果表明，E ₂ s ¹烃源岩沉积在盐度较高的湖泊环境中，造成水体分层和底部缺氧条件。常规甾烷、二甾烷、4α-甲基-24-乙基胆甾烷、24-去甲胆甾烷、24- n研究样品中的-丙基胆甾烷、藿烷、2α-甲基藿烷和3β-甲基藿烷表明甲藻、硅藻、浮藻纲、蓝细菌、根瘤菌目和好氧甲烷氧化菌是E ₂ s ¹的主要生物来源。其中，甲藻与富含有机质E ₂ s ¹烃源岩的形成密切相关，这得到了TOC或HI值与4α-甲基-24-乙基胆甾烷（甲藻生物标志物）含量的正相关关系的支持。研究样本中的微量陆地高等植物生物标志物表明它们对有机物的贡献是有限的。这与在 E₂ s ¹光学显微照片下的样品。渤海湾盆地始新世广泛发生的海洋侵入事件也可能发生在辽东湾次盆地 E ₂ s ¹沉积期间，这得到了典型的海洋藻类生物标志物（24-n-丙基胆甾烷）的支持。