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报道了扬子克拉通峡东地区新元古代至寒武纪含碳黑色泥质岩的Re-Os同位素和微量元素地球化学组成特征,并对地层沉积环境的演化性质及其地质意义进行了讨论.研究表明:(1)峡东地区新元古代晚期-寒武纪早期细粒碎屑沉积岩Os同位素初始比值呈规律变化,且具高Os同位素初始比值的层位与前人研究中发现的C同位素负漂移地层相对应;(2)南沱组冰碛岩具高放射成因Os同位素组成特征,而其上覆盖帽碳酸盐岩为低放射成因Os同位素比值,向上地层Os同位素初始比值表现为局部波动、总体增高的演化趋势;(3)微量元素U/Th比值与δU值指示莲沱组砂岩与南沱组冰碛岩具氧化环境的特征,而陡山沱组、灯影组以及水井沱组底部黑色泥质岩则形成于相对还原环境;(4)Y/Ho比值和δCe值的负相关性特征指示部分地层沉积过程中有海底热液物质参与,应为导致剖面上部分层位出现低放射性成因Os同位素组成的重要原因之一.高Os同位素比值和深海的脉冲式演化以及古生物群的产出之间很好的对应关系为探讨大陆风化与大气和海洋中氧气含量增加的联系提供了新的地球化学证据.南沱组冰碛岩Os同位素以及微量元素特征暗示其并非形成于完全冰封的地球表面环境,而是存在较强的大陆岩石风化作用.
The Re-Os isotope and trace element geochemical characteristics of the Neoproterozoic to Cambrian carbonaceous black argillaceous rocks in the Yangtze craton, eastern China were reported. The evolutionary properties of the sedimentary environment and its geological significance were also discussed. The results show that: (1) The initial Os isotopic ratios of fine clastic sedimentary rocks in the Late Neoproterozoic to the Early Cambrian show regular changes in the eastern part of the Yangtze River, and the strata with high Os isotopic ratios are similar to the C isotopes found in previous studies (2) The Oscillatory rocks of the Nantuo Formation are characterized by high-frequency Os isotope composition, whereas the capped carbonate rocks are Os isotopic ratios with low radiogenic origin and the Os isotopic initial ratios of the upwelling formations are locally (3) The U / Th ratios and δU values of trace elements indicate the characteristics of oxidation environment of the lantu rocks and the moraine rocks of Nantuo Formation. However, the Doushantuo Formation, Deng Ying Formation and Shuijingtuo Formation (4) The negative correlation between Y / Ho ratio and δCe value indicates that some seafloor hydrothermal materials are involved in the sedimentary process of some strata, which should lead to the low level of some strata put One of the important reasons for the radiogenic Os isotopic composition is the good correspondence between the high Os isotope ratio and the pulsatile evolution of the deep ocean and the paleontology output. To provide a link between continental weathering and the increase of oxygen content in the atmosphere and oceans The new geochemical evidence shows that the Os isotopic and trace element characteristics of the moraine rocks in the Nantuo Formation suggest that they are not formed on the completely frozen surface of the Earth’s environment but rather have stronger continental rock weathering.