Geochemical characteristics and significance of the shale of Lower Cambrian Hetang Formation in the southern Anhui Province of Lower Yangtze area

The Lower Cambrian organic-rich black shale is well developed in southern China, which is wide in distribution, large in thickness and high in total organic carbon. It has great resource potential of shale gas and is expected to be an important succeeding field to meet the future increase in shale gas demand. This paper is devoted to the first parameter well XY1 of the Lower Cambrian Hetang Formation shale gas in the lower Yangtze area. Using cores and geochemical data, element geochemical characteristics and their paleoenvironmental significance are studied. The results show that the major elements SiO₂ and K₂O are relatively rich, and the others are lower to certain extent. As for trace elements, Sr and Rb are depleted, and the elements of Ni, Co and Ba are obviously enriched. The black shale of Hetang Formation is a kind of continental margin deposits. Silica mainly came from siliceous organisms under a warm and humid climate, and deposited in saline water, which is favorable to the deposition of organic matter. It is inferred that paleoproductivity of the Hetang Formation is high. The anaerobic water environment is conducive to the preservation of organic matter.