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。
The second Great Oxidation Event （GOE2）had occurred during Neoproterozoic-Early Cambrian transition period, where the redox-sensitive elements of sedimentary rocks had been gradually enriched during this period. Selenium is a typical redox-sensitive element, and seleniumenriched sedimentary rocks may indicate changes in ocean redox environment. In order to discuss the relationship between redox conditions and Se enrichment of this period, Se and other redox-sensitive elements in the black shales of Member IV, the upper Doushantuo Formation in Yichang, South China, were systematically investigated. Results show that average Se value of most samples is 14.49×10-6, which is much higher than the Se crustal abundance （0.05 × 10-6）. Se enrichment presents different degrees of relevance with other elements of Co, Ag, V, etc. The Mo-U conversation indicates the fluctuating anoxic environment of the Ediacaran Doushantuo Formation in Yichang Area. Selenium enrichment of the Ediacaran Doushantuo Formation in Yichang was controlled by biological activity, sulfidic water floating and instability anoxic marine environment. The local factors also contribute to the different degrees of Se enrichment of individual sections. Compared with Precambrian black shale, Se enrichment is significant, indicating strong input by continental weathering.
出处
《矿物学报》
CSCD
北大核心
2017年第3期258-268,共11页
Acta Mineralogica Sinica
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)
作者简介
通讯作者，E—mail：fanhaifeng@mail．gyig．ae．cn
