东濮凹陷北部沙河街组三段中亚段沉积环境分析
Analysis of the Sedimentary Environment in the North of Dongpu Depression During the Deposition of the Middle Section of the Third Member of the Shahejie Formation

摘要： 东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩，这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积，单个盐韵律厚度从几米到十几米，烃源岩有机质丰度高、类型好。平面上，两者在湖盆沉积沉降中心共生；垂向上，高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明，凹陷北部沙三中亚段为深水沉积的还原环境，古盐度较高，达到半咸水-咸水沉积；微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。
Abstract: The salt rocks and source rocks are extensively developed in the middle section of the third Member of Shahejie Formation in the North of Dongpu Depression and the two seemingly coexisting substances are intermixed here. In this period, the sedimentary characteristics of the study area were the continuous deposition of multisalt rhythm and multilayer hydrocarbon source rocks. Individual salt rhythms vary in thickness from a few meters to more than ten meters, the hydrocarbon source rocks have high organic matter abundance and the type is good. In the plane, the two are symbiotic with the sedimentation center of the lake basin, and in the vertical, high organic matter abundance, good kerogen type and high salinity formation have a better correspondence.Therefore, it has become an important research object for the restoration of paleoclimate and paleoenvironment. We studied the sedimentary environment of the middle section of the third Member of Shahejie Formation in the North of Dongpu Depression through petrology, paleontology, and the methods of Sr/Ba,B/Ga,(V+Ni+Mn)，Fe/Mn，Sr/Cu，Mg/Ca，V/(V+Ni),as well as REE content and chlorine isotope. The results showed that the sedimentary environment of the middle section of the third Member of Shahejie Formation in the North of Depression was the reduction environment of the deepwater deposition, and the ancient salinity was a little high,which is semisaltwatersaltwater deposition. The trace elements and the spore fossils indicate the environment of the middle section of the third Member of Shahejie Formation in the study area was warm and humid