Forty five shale core samples were collected from the Chang-7 section of Yanchang Formation of YK1 well，south of the Ordos Basin. And the total organic carbon content （TOC） and Rock-Eval prolysis of these samples were analyzed. Meanwhile，fifteen samples were selected to further conduct the experiments of the organic carbon isotopes，chloroform bitumen “A” content，and trace elements. The results show that the organic matter indexes （TOC，chloroform bitumen“A”，hydrocarbon generating potential）of Chang-7 section have good positive correlations，and the organic matter abundance of Chang-73 is higher than that of Chang-71 and Chang-72. The data of the carbon isotopes of organic matter indicates that the organic matter types in Chang-73 are dominated by TypeⅠ. The Chang-71 and Chang-72 source rocks have mixed types，which are dominated by Type Ⅰand Type Ⅱ. The redox proxies of U/Th、δU and V/(V+Ni) show that the Chang-7 deposition was reducing environment-strong reducing environment. Compared with the Chang-72 and Chang-71，Chang-73 deposition environment was more reduction，which probably was anaerobic and developed sulfate-reduction bacteria. The high contents of P element of the Chang-7 shale demonstrate a higher paleoproductivity during the depositional process of Chang-7 section，while TOC content has a positive correlation with redox proxies and P contents，suggesting that the organic matter contents of Chang-7 shale are controlled by redox condition and paleoproductivity at the same time. Therefore，the organic matter accumulation in Chang-7 section probably belongs to “Productivity Model”. That the organic matter accumulation in Chang-7 section is resulted by relatively high paleoproductivity，then the organic matter decomposition reduced the oxygen of the depositional water，this is favorable for the preservation of the residual organic matter. Integrated the former shale gas researches，the organic matter enriched Chang-73 is the most favorable target for shale-gas enrichment.
Ma Yu Zhou Shixin Tao Huifei Fu Deliang Li Jing Li Yuanju Li Chengcheng Yang Yanan. Sedimentary characteristic and organic matter enrichment factors of the Chang-7 section shale of Yanchang Formation in the south of Ordos Basin[J]. Chinese Journal of Geology, 2017, 52(1): 106-122.