Geochemical characteristics and sedimentary environment differences of Paleogene source rocks in lacustrine basins with different salinities

• Published in: Petroleum science and technology 2024-11, Vol.42 (25), p.4234-4256
• Main Authors: Liu, Xiheng, Lu, Jungang, Dan, Weining, Shi, Yulei, Liu, Jing, Tian, Sisi, Hu, Chenguang, Li, Jiarun
• Format: Article
• Language: English
• Subjects: Abundance; Barium; Basins; geochemical characteristics; Geochemistry; Hetao Basin; Hydrocarbons; Organic matter; Paleoclimatology; Pearl River Mouth Basin; Rocks; saline lake; Salinity; sedimentary environment; Strontium
• ISSN: 1091-6466; 1532-2459
• DOI: 10.1080/10916466.2023.2262503

Geochemical characteristics and sedimentary environment of source rocks in the Paleogene Wenchang Formation (E 2 W) of the Pearl River Mouth Basin (PRMB) and the Linhe Formation (E 3 L) of the Hetao Basin are studied. Geochemical experiments were carried out, and the results shows: (1) E 2 W source rocks have a high abundance of organic matter (OM) and, are in the mature stage with good hydrocarbon generation potential. The paleoclimate was warm and humid, and was oxidative freshwater. (2) The hydrocarbon generating OM of E 2 W and E 3 L were mainly aquatic organisms, while E 1 W was mainly terrestrial organisms. Compared with the E 2 W source rocks, the abundance and maturity of OM in the E 3 L are lower. The E 3 L source rocks is in a reducing environment, the salinity of the water body is relatively high, and there are obvious vertical stratification phenomena. (3) OM in freshwater basins is less affected by paleoclimate, paleoredox, and paleosalinity, while in the saline lake basins is greatly affected by paleosalinity. Low salinity (Sr/Ba < 1.5, Cl < 400 ppm) and high salinity (Sr/Ba > 2.0) are not conducive to organic enrichment, and abundance is also positively correlated with reduction.