| 黔西织金矿区乐平世煤系菱铁矿成因探讨 |
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| 引用本文： | 张涛,沈玉林,李壮福,金军,宗毅,刘近帮,郑俊.黔西织金矿区乐平世煤系菱铁矿成因探讨[J].高校地质学报,2018,24(4):481. |
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| 作者姓名： | 张涛 沈玉林 李壮福 金军 宗毅 刘近帮 郑俊 |
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| 作者单位： | 中国矿业大学资源与地球科学学院;中国矿业大学煤层气资源与成藏过程教育部重点实验室;贵州省煤层气页岩气工程技术研究中心;贵州省煤田地质局 |
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| 摘 要： | 黔西织金矿区乐平世煤系中的菱铁矿以多种微观形态产出,基于镜下薄片观测、泥岩微量元素分析,探讨了菱铁矿成因及演化。研究表明菱铁矿可划分为第一世代的胶状集合体、第二世代圈层结构发育不良的球粒及第三世代圈层结构发育完好的鲕粒与菱面体三个成岩世代产物。菱铁矿胶状集合体是在成矿组分(Fe~(2+)与CO_3~(2-))浓度达到超饱和状态时快速结晶形成的;圈层结构发育不良的菱铁矿球粒是成矿物质围绕第一世代形成的菱铁矿胶粒聚集而成;圈层结构发育完好的菱铁矿鲕粒是大量放射状菱铁矿线晶以第二世代的球粒为核心连续共轴生长而成,晚二叠世脉动式的海侵可能是菱铁矿在结晶非平衡态与平衡态与之间往复循环驱动因素,最终形成了同心圈层结构,而同心圈层发育完好的菱面体状菱铁矿可能是成矿条件的变化促使鲕粒从放射状生长向自形菱面体生长而成。
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| 关 键 词： | 胶状集合体 球粒 鲕粒 菱面体 成岩世代 成因 |
Genesis of Siderite Precipitated in the Lopingian Coal Measures in Zhijin Mining Area,Western Guizhou |
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| ZHANG Tao,SHEN Yulin,LI Zhuangfu,JIN Jun,ZONG Yi,LIU Jinbang,ZHENG Jun.Genesis of Siderite Precipitated in the Lopingian Coal Measures in Zhijin Mining Area,Western Guizhou[J].Geological Journal of China Universities,2018,24(4):481. |
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| Authors: | ZHANG Tao SHEN Yulin LI Zhuangfu JIN Jun ZONG Yi LIU Jinbang ZHENG Jun |
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| Abstract: | Siderite with a wide spectrum of micro morphologies has been found in the Longtan Formation of the Lopingian coal-bearing
measures in Zhijin Mining area, western Guizhou. The origin and phase evolution of siderite are discussed based on thin section
observations and trace elements analysis. The study suggests that siderite with various micro morphologies could be divided into three
diagenetic generation products, comprising siderite colloidal aggregates precipitated during the first generation, poorly zoned
spherulites developed during the second generation, and perfectly zoned sphaerosiderites as well as rhombohedra precipitated during
the third generation. Siderite colloidal aggregates were crystallized rapidly when the concentration of metallogenic components (Fe2 +
and CO32-) reached their supersaturation stage. Poorly zoned spherulites were formed by adhering metallogenic materials to siderite
colloidal particles precipitated during the first generation. Perfectly zoned sphaerosiderites were developed by the syntaxial and
continuous overgrowth of numerous radiating linear crystals surrounding the spherulites developed during the second generation.Moreover, the pulse-like transgression during the Late Permian might have acted as an external driving factor which would lead to the
reciprocating cycle of siderite between crystalline equilibrium state and non-equilibrium state, and finally the concentric zonation
structure was formed. The formation of perfectly zoned sidetite rhombohedra might have resulted from changes of growth patterns from
the radiating growth to the rhombohedral growth caused by variations of metallogenic conditions. |
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| Keywords: | colloidal aggregates spherulite sphaerosiderite rhombohedron diagenetic generation genesis |
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