| 湘西南南华系大塘坡组锰矿地球化学特征与沉积环境分析:以湖南靖州照洞锰矿床为例 |
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| 引用本文： | 李凤杰,雷玉龙,龚光林,张昊,沈凡,荆锡贵,成晓雨.湘西南南华系大塘坡组锰矿地球化学特征与沉积环境分析:以湖南靖州照洞锰矿床为例[J].地球科学,2019,44(10):3484-3494. |
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| 作者姓名： | 李凤杰 雷玉龙 龚光林 张昊 沈凡 荆锡贵 成晓雨 |
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| 作者单位： | 1.成都理工大学油气藏地质及开发国家重点实验室, 四川成都 610059 |
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| 基金项目： | 中国地质调查局公益性基础地质调查项目DD20160032 |
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| 摘 要： | 为了分析湘西南南华系大塘坡组照洞锰矿的沉积环境，对照洞锰矿床进行了岩石学和地球化学研究.分析认为:照洞锰矿赋存于大塘坡组底部碳酸锰层中，包括条纹状菱锰矿和块状菱锰矿两种矿石类型.湘西南照洞锰矿的常量元素TiO2、SiO2、K2O、Fe2O3、S与Al2O3之间呈现良好的正相关关系，CaO、MgO、MnO、P2O5和Al2O3之间呈负相关关系，常量元素之间的相关性与黔东、湘西的典型锰矿之间存在一致性，反映这些锰矿可能具有相似的成矿背景.照洞锰矿的Fe/Mn值低，Th/U、Ni/Co、V/Cr、V/（V+Ni）等沉积环境古氧相的指标显示，湘西南照洞锰矿形成时的水体处于常氧-贫氧的条件下.湘西南照洞锰矿稀土元素总量较高，PAAS标准化稀土元素配分模式呈现轻、重稀土亏损，中稀土富集的特征，具有弱的Ce正异常，类似现代海底铁锰结核的稀土元素配分特征.
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| 关 键 词： | 常量元素 微量元素 沉积环境 大塘坡组 矿床学 |
| 收稿时间： | 2019-04-10 |
Geochemical Characteristics and Sedimentary Environment Analysis from Datangpo Formation in Neoproterozoic Nanhua System,Southwestern Hunan Province—An Example from Zhaodong Manganese Ore Deposits in Jingzhou County,Hunan Province,China |
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| Abstract: | In order to analyze sedimentary environment of Zhaodong manganese ore deposits located in the Southwestern Hunan Province from Datangpo Formation in Neoproterozoic Nanhua System (Cryogenian), the petrology and geochemistry of the manganese ore deposits were studied, considering that the Zhaodong manganese ore deposits are mainly hosted in manganous carbonate layer that includes two types of manganese-containing minerals, namely, striped rhodochrosite and massive rhodochrosite at the bottom of the Datangpo Formation. The major elements of Zhaodong manganese ore deposits in Datangpo Formation in Southwestern Hunan Province show positive correlation between the TiO2, SiO2, K2O, Fe2O3, S and Al2O3 and negative correlation between CaO, MgO, MnO, P2O5 and Al2O3, which is consistent with those of typical manganese ore deposits in eastern of Guizhou and western of Hunan Province. It reflects that these manganese ore deposits may have similar mineralization background. Zhaodong manganese ore deposits are characterized by the low Fe/Mn ratios. The ratios of redox sensitive trace elements which can be regarded as marker of sedimentary environment and paleo-oxygenation facies such as Th/U, Ni/Co, V/Cr and V/(V+Ni) indicate that the manganese ore deposits were formed in sub-oxidation to oxidation water condition in Zhaodong manganese ore deposits of the Southwestern Hunan Province. The Zhaodong manganese ore deposits of the Southwestern Hunan Province are characterized geochemically by high ∑ REE contents, PAAS-normalized REE patterns similar to that of ferromanganese nodules in modern ocean bottom, and positive Ce anomaly. |
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