Geochemical Characteristics and Provenance Analysis of Middle Jurassic Xintiangou Formation in Dijiang-Changshou Area

This paper takes the Xintiangou Formation in Dianjiang-Changshou area of eastern Sichuan as the research object, aiming at studying the source of clastic rocks and the tectonic environment of the source area in Xintiangou Formation, and provides a basis for further study of Jurassic lake basin evolution in eastern Sichuan Basin. In this paper, one profile of Xintiangou Formation was measured in Dianjiang County and Changshou District, respectively, understanding the lithologic characteristics and sedimentary environment of Xintiangou Formation.28 geochemical samples were collected from 2 sections, and all samples were analyzed for major, trace and rare earth elements. Among them, Al₂O₃/TiO₂, La/Th-Hf and Co/Th-La/Sc diagrams indicate that the source rocks are felsic, andesitic and ancient sediments. Rare earth elements La, La_n/Yb_n, ΣLREE/ΣhREE value, La/Y-Sc/Cr diagram, and main elements TFe₂O₃+MgO, SiO₂/Al₂O₃, K₂O/Na₂O, et a1 average, K₂O/Na₂O-SiO₂ discriminant diagram, and the discrimination diagrams of Sc/Cr values, Zr/Hf values, et a1 and Th-Co-Zr/10, La-Th-Sc, Th-Sc-Zr/10 tectonic environment shows that tectonic setting of source area is continental island arc and passive continental margin.Combined with previous research results, it can be seen that the material of Xintiangou Formation in the study area comes from the South Qinling-Daba Mountains area, and the materials are mainly felsic rocks, andesitic rocks and ancient sediments. The tectonic setting of the provenance area is the continental island arc environment and passive continental margin of different tectonic stages of the South Qinling-Daba Mountains area.