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    与火山活动有关的热水沉积锰矿——以贵州二叠纪锰矿为例

    Hydrothermal sedimentary manganese deposits associated to volcanic activities—Permian manganese deposit in Guizhou

    • 摘要: 提要:贵州产于中二叠统茅口组第二段的锰矿、铁锰矿、含锰菱铁矿,均分布在茅口晚期黔中台沟内。东部遵义一带为碳酸盐锰矿床,西部宣威—水城一带主要为锰帽型次生氧化锰矿床。笔者目的在于探讨黔中台沟锰矿成矿条件,以期扩大找矿远景。研究表明,区内各类锰矿石和矿胚层岩石都是在热水中生成的,证据是:①有大量热水沉积的标志性矿物;②常量、微量元素及稀土元素均具有热水沉积的特征;③流体包裹体均一温度达90~275℃等。锰矿的形成可能与峨眉地幔柱演化的中晚期阶段密切相关。茅口期玄武岩的喷出活动,有利于黔中台沟内硅灰泥锰质组合的形成。东部遵义一带的锰矿,被严格限制在热水喷发形成的硅质角砾岩分布区内,结合其他特征等,说明该区锰矿形成可能与强烈的热水活动有关。

       

      Abstract: Abstract:Manganese deposits, ferromanganese deposits and manganiferous siderite deposits occurring in the Second Member of the Middle Permian Maokou Formation in Guizhou are all distributed in platform gullies in central Guizhou. There are carbonate manganese deposits in the Zunyi area in the east and mainly manganese gossan-type secondary manganese oxidized deposits in the Xuanwei-Shuicheng area in the west. The purpose of this paper is to discuss the mineralization conditions of manganese deposits in order to extend ore prospects. Study shows that various manganese ore types and rocks of ore embryo layers formed by hydrothermal processes. The evidence is as follows:(1) there are many diagnostic minerals of hydrothermal deposition;(2) major and trace element and REE data all show characteristics of hydrothermal deposition;and (3) he homogenization temperatures of fluid inclusions range from 90 to 275℃. The formation of the manganese deposits is probably closely related to the middle and late stages of the evolution of the Emeishan mantel plume. The outpouring of Maokouan basalt was favorable to the formation of the silica-lime-mud-manganese association in the platform gullies of central Guizhou. Manganese deposits in the Zunyi area in the east are strictly confined in the area of siliceous breccia formed by hydrothermal eruption. Based on these, combined with other characteristics, it is thought that the formation of manganese deposits in the study area is related to strong hydrothermal eruption.

       

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