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Shale gas exploration in the Upper Yangtze Basin has been conducted for over ten years. The successful drillings in the region suggest that well-planned geological survey and reservoir evaluation are indispensable for the success of these drillings. In this study, the shale gas potential of Late Ordovician to Early Silurian mudstones/shales of the Wufeng–Longmaxi formations in the Upper Yangtze Basin was evaluated. First, all of the available geochemical and petrological data from Late Ordovician to Early Silurian mudstones/shales in the region were compiled. Distributional patterns of total organic carbon (TOC) values, thickness, thermal maturity, and burial depth of organic-rich mudstones/shales from the targeted formations were then analyzed. Our results show that TOC values range from 1.20 to 5.12%; R o values range from 1.92 to 2.86%; porosity varies from 0.77 to 9.2%; permeability varies from 0.015 to 1.99 md; the composition of quartz group of mineral component ranges from 18 to 85%, 59% in average; and clay mineral component ranges from 7 to 56%, 31% in average. Finally, based on these comprehensive analysis, three areas with great potential, that is, Luzhou-Xishui, western Chongqing, and Wulong-Shizhu, were selected as targets for further shale gas exploration and exploitation.

The petrology, mineralogy, elemental geochemistry, biology and PGEs characteristics of the black shale of the Wufeng and Longmaxi Formation in the CN outcrop of the Sichuan Basin are studied in this paper. The distribution and change in PGEs at different horizons are summarized, and the reasons for PGEs enrichment are discussed. The results show that the PGEs in the organic-rich shale segment are obviously enriched, which is positively correlated with the Total Organic Carbon (TOC) content and has a Pt–Pd distribution characteristic. δEuN, Pd/Pt, (Pt + Pd)/(Os + Ru + Ir), etc., and SiO2–Al2O3 and It/Pt–Pd/Pt discrimination diagrams, indicate that they are not extraterrestrial sources, nor are they the origins of normal seawater deposition but they are related to hydrothermal deposition. The enrichment process of PGEs is relatively complicated and is controlled by the impact of the sedimentary environment in the restricted basin. The anoxic water environment and organic-rich environment are the main factors of PGEs enrichment. PGEs and TOC have a good positive correlation and can be used as index parameters for sedimentary environments and organic matter enrichment.