The fine-grained rocks in the Paleogene Shahejie Formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin, are extremely important source rocks. These Paleogene rocks are mainly subdivided into organic-rich black shale and gray mudstone. The average total organic carbon contents of the shale and mudstone are 11.5 wt.% and 8.4 wt.%, respectively. The average hydrocarbon (HC)-generating potentials (which is equal to the sum of free hydrocarbons (S₁) and potential hydrocarbons (S₂)) of the shale and mudstone are 39.3 mg HC/g rock and 28.5 mg HC/g rock, respectively, with mean vitrinite reflectance values of 0.82% and 0.81%, respectively. The higher abundance of organic matter in the shale than in the mudstone is due mainly to paleoenvironmental differences. The chemical index of alteration values and Na/Al ratios reveal a warm and humid climate during shale deposition and a cold and dry climate during mudstone deposition. The biologically derived Ba and Ba/Al ratios indicate high productivity in both the shale and mudstone, with relatively low productivity in the shale. The shale formed in fresh to brackish water, whereas the mudstone was deposited in fresh water, with the former having a higher salinity. Compared with the shale, the mudstone underwent higher detrital input, exhibiting higher Si/Al and Ti/Al ratios. Shale deposition was more dysoxic than mudstone deposition. The organic matter enrichment of the shale sediments was controlled mainly by reducing conditions followed by moderate-to-high productivity, which was promoted by a warm and humid climate and salinity stratification. The organic matter enrichment of the mudstone was less than that of the shale and was controlled by relatively oxic conditions.

渤海湾盆地黄骅凹陷南堡凹陷古近系沙河街组细粒岩是极其重要的烃源岩。这些古近系岩石主要细分为富含有机质的黑色页岩和灰色泥岩。页岩和泥岩的平均总有机碳含量分别为 11.5 wt.% 和 8.4 wt.%。平均碳氢化合物 (HC) 生成潜力（等于游离碳氢化合物 (S ₁ ) 和潜在碳氢化合物 (S ₂)) 的页岩和泥岩分别为 39.3 mg HC/g 岩石和 28.5 mg HC/g 岩石，平均镜质反射率值分别为 0.82% 和 0.81%。页岩中有机质的丰度高于泥岩，主要是由于古环境的差异。蚀变值和 Na/Al 比值的化学指数显示页岩沉积期间气候温暖湿润，泥岩沉积期间气候寒冷干燥。生物衍生的 Ba 和 Ba/Al 比率表明页岩和泥岩的生产力较高，而页岩的生产力相对较低。页岩形成于淡水至微咸水中，而泥岩沉积于淡水中，前者盐度较高。与页岩相比，泥岩经历了更高的碎屑输入，表现出更高的 Si/Al 和 Ti/Al 比。页岩沉积比泥岩沉积更缺氧。页岩沉积物有机质富集主要受还原条件控制，其次是中高生产力，温暖湿润气候和盐分分层促进了有机质富集。泥岩有机质富集程度低于页岩，受相对含氧条件控制。