applied sciences Article Geochemical Characteristics of the Lower Cretaceous Hengtongshan Formation in the Tonghua Basin, Northeast China: Implications for Depositional Environment and Shale Oil Potential Evaluation Wentong He 1,2,3 , Youhong Sun 1,2,4,* and Xuanlong Shan 5,* 1 College of Construction Engineering, Jilin University, Changchun 130021, China;
[email protected] 2 National-Local Joint Engineering Laboratory of In-situ Conversion, Drilling and Exploitation Technology for Oil Shale, Jilin University, Changchun 130021, China 3 Key Laboratory of Oil Shale and Coexistent Energy Minerals of Jilin Province, Changchun 130061, China 4 School of Engineering and Technology, China University of Geosciences, Beijing 100191, China 5 College of Earth Sciences, Jilin University, Changchun 130061, China * Correspondence:
[email protected] (Y.S.);
[email protected] (X.S.) Abstract: The Tonghua Basin in Northeast China potentially contains shale oil and gas resources, but the exploration and development of these resources has been limited. The Sankeyushu depres- sion represents the sedimentary center of the Tonghua Basin, and a large thickness of shale, the Hengtongshan Formation, was deposited in this depression. Exploratory engineering discoveries in recent years have confirmed that the Hengtongshan Formation has the potential to produce oil and gas. A series of methods, including inorganic and organic geochemistry and organic petrology, have been used to study the source material, organic matter maturity, depositional environment and oil-generating potential of the Hengtongshan Formation. Investigation of drill core samples has revealed that the Hengtongshan Formation in the Sankeyushu depression is mainly composed of black shale, with a small amount of plant fossils and thin volcanic rocks, and the content of brittle Citation: He, W.; Sun, Y.; Shan, X.