宜昌地区埃迪卡拉纪陡山沱组硒的富集与地质意义

发布时间：2018-12-11 21:35

【摘要】：新元古代一早寒武世过渡时期发生了地质历史上第2次大氧化事件,沉积岩中的氧化还原敏感元素在这一时期出现不同程度的富集。分散元素硒是典型的氧化还原敏感元素,沉积岩中硒的富集可以指示海洋氧化环境的变化。为了讨论这一时期硒的富集与海洋氧化还原状态的关系,本文对宜昌地区陡山沱组第4段黑色页岩中的Se及其他氧化还原敏感元素进行了系统地分析。结果发现,Se含量范围1.0×10~(-6)~58.0×10~(-6),平均含量14.49×10~(-6),远高于Se的地壳丰度(0.05×10~(-6))。Se元素的富集同Co、Ag和V等都有不同程度的相关性。利用Mo-U关系指示了这一时期为缺氧环境。宜昌地区埃迪卡拉纪陡山沱组硒的富集作用与硫化水体波动、生物作用和不稳定的缺氧海洋环境有关,不同剖面的区域因素也造成了富集程度的不同。与前寒武纪的黑色页岩相比,Se含量发生了明显富集,暗示这一时期强烈的大陆风化输入,进一步指示大气的氧化。
[Abstract]:During the transition period of Neoproterozoic to early Cambrian, the second great oxidation event occurred in geological history, and the redox sensitive elements in sedimentary rocks were enriched to varying degrees in this period. Selenium is a typical redox sensitive element. The enrichment of selenium in sedimentary rocks can indicate the change of marine oxidation environment. In order to discuss the relationship between selenium enrichment and marine redox state in this period, Se and other redox sensitive elements in the black shale of the fourth member of Doushantuo formation in Yichang area were systematically analyzed. The results show that the Se content ranges from 1.0 脳 10 ~ (-6) to 58.0 脳 10 ~ (-6), and the average content is 14.49 脳 10 ~ (-6), which is much higher than the crustal abundance of Se (0.05 脳 10 ~ (-6). Se). The correlation between Ag and V was different. The use of the Mo-U relationship indicates that this period is anoxic. The enrichment of selenium in the Doushantuo formation of the Ediacaran period in Yichang area is related to the fluctuation of sulphide water body, biological action and unstable anoxic marine environment, and the regional factors of different profiles also result in different levels of enrichment. Compared with the black shale of the Precambrian period, the Se content is obviously enriched, indicating the strong continental weathering input in this period and further indicating the oxidation of the atmosphere.
【作者单位】：贵州大学资源与环境工程学院;贵州大学研究生院;中国科学院地球化学研究所矿床地球化学国家重点实验室;
【基金】：中国地质调查局项目(编号:1212011120354) 国家自然科学基金项目(编号:41273024;40804019) 中国科学院西部之光重点项目(2014) 贵州大学研究生创新基金项目(编号:研理工2015059)
【分类号】：P618.76

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