摘要
Lower Silurian Longmaxi Shale(SLS) in southeastern Sichuan Basin, China, was analyzed for major and selected trace elements, and their provenance, intensity of palaeoweathering of the source rocks were analyzed based on these elements. The results show that SiO_2, Al_2O_3 and Fe_2O_3, are dominant major elements with average contents of 60.59%, 15.91% and 5.87% in Upper Silurian Longmaxi Shale(USLS), and 65.14%, 13.24% and 4.68% in Lower Silurian Longmaxi Shale(LSLS). The TiO_2-Zr plot, Hf(ppm) versus La/Th discriminant diagram, and abundance of Cr and Ni suggest a dominantly felsic source for the Longmaxi sediments. Average chemical index of alteration(CIA), plagioclase index of alteration(PIA) values(64.05% and 72.86%, respectively) imply low-degree chemical weathering of the source material in early Longmaxi time, and average CIA, PIA values(68.44% and 80.35%, respectively) imply moderate chemical weathering of the source material in late Longmaxi time.
Lower Silurian Longmaxi Shale（SLS） in southeastern Sichuan Basin, China, was analyzed for major and selected trace elements, and their provenance, intensity of palaeoweathering of the source rocks were analyzed based on these elements. The results show that SiO_2, Al_2O_3 and Fe_2O_3, are dominant major elements with average contents of 60.59%, 15.91% and 5.87% in Upper Silurian Longmaxi Shale（USLS）, and 65.14%, 13.24% and 4.68% in Lower Silurian Longmaxi Shale（LSLS）. The TiO_2-Zr plot, Hf（ppm） versus La/Th discriminant diagram, and abundance of Cr and Ni suggest a dominantly felsic source for the Longmaxi sediments. Average chemical index of alteration（CIA）, plagioclase index of alteration（PIA） values（64.05% and 72.86%, respectively） imply low-degree chemical weathering of the source material in early Longmaxi time, and average CIA, PIA values（68.44% and 80.35%, respectively） imply moderate chemical weathering of the source material in late Longmaxi time.
基金
Project(41302076)supported by the National Natural Science Foundation of China
Project(BJ14266)supported by MOST Special Fund from the State Key Laboratory of Continental Dynamics,Northwest University,China
Project(2014JQ5191)supported by Natural Science Basic Research Plan of Shaanxi Province,China
