| 西天山松湖铁矿床磁铁矿标型特征及其对矿床成因的限定 |
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| 引用本文： | 荆德龙,汪帮耀,王志华,赵晓健,滕家欣,姜常义,杨镇熙.西天山松湖铁矿床磁铁矿标型特征及其对矿床成因的限定[J].地球科学与环境学报,2021(1):80-99. |
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| 作者姓名： | 荆德龙 汪帮耀 王志华 赵晓健 滕家欣 姜常义 杨镇熙 |
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| 作者单位： | 中国地质调查局西安地质调查中心自然资源部岩浆作用成矿与找矿重点实验室;长安大学地球科学与资源学院;甘肃省地质矿产勘查开发局第四地质矿产勘查院 |
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| 基金项目： | 中国地质调查局地质调查项目(12120114007501,12120113044000,DD20190143);陕西省自然科学基础研究计划项目(2019JQ-934,2020JQ-439,2020JQ-440);国家自然科学基金项目(41402079)。 |
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| 摘 要： | 松湖铁矿床位于新疆西天山伊犁地块东北缘阿吾拉勒成矿带西段,赋矿围岩为下石炭统大哈拉军山组安山岩及安山质火山碎屑岩。现有研究对于该矿床成因尚有争议,焦点在于是否存在矿浆(或岩浆)成因磁铁矿。据此,系统采集松湖铁矿床内各类典型矿石开展详细的磁铁矿标型特征研究,并利用LA-ICP-MS技术分析了磁铁矿的微量元素组成。结果表明:浸染状与块状矿石中磁铁矿具有高V、Ni、Ti含量,低Al、Mn、Co、Zn、Sn含量等岩浆磁铁矿地球化学特征;而条带状与角砾状矿石胶结物中磁铁矿Mg、Al、Mn、Zn含量高,V含量相对较低,各元素含量均与矽卡岩型矿床中的热液磁铁矿相当。磁铁矿包裹体爆裂温度指示:浸染状及块状矿石中存在两期包裹体,形成温度分别为328℃~397℃和424℃~485℃;条带状及角砾状矿石中粗粒磁铁矿包裹体数量较少,形成温度为343℃~385℃。综合矿物标型特征,认为各类矿石中浸染状矿石形成温度最高,其次为块状矿石,再次为角砾状矿石,条带状矿石形成温度最低,这也是各类矿石在松湖铁矿床成矿过程中的形成顺序。岩相学及微量元素地球化学特征均证实松湖铁矿床形成过程中存在矿浆成矿阶段,晚期热液成矿以高温火山热液充填交代成矿为主,而非沉积成矿。综合矿床地质及磁铁矿标型特征,认为松湖铁矿床成因类型应属火山岩浆-热液复合型铁矿床。
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| 关 键 词： | 矿床成因 铁矿床 磁铁矿 标型特征 微量元素 爆裂温度 晶胞参数 西天山 |
Typomorphic Characteristics of Magnetite from Songhu Iron Deposit in West Tianshan,China and Their Constrains on Ore-forming |
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| JING De-long,WANG Bang-yao,WANG Zhi-hua,ZHAO Xiao-jian,TENG Jia-xin,JIANG Chang-yi,YANG Zhen-xi.Typomorphic Characteristics of Magnetite from Songhu Iron Deposit in West Tianshan,China and Their Constrains on Ore-forming[J].Journal of Earth Sciences and Environment,2021(1):80-99. |
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| Authors: | JING De-long WANG Bang-yao WANG Zhi-hua ZHAO Xiao-jian TENG Jia-xin JIANG Chang-yi YANG Zhen-xi |
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| Institution: | (Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits of Ministry of Natural Resources,Xi an Center of Geological Survey,China Geological Survey,Xi an 710054,Shaanxi,China;School of Earth Science and Resources,Chang an University,Xi an 710054,Shaanxi,China;The Fourth Institute of Geological and Mineral Exploration,Gansu Provincial Bureau of Geology and Mineral Resources,Jiuquan 735000,Gansu,China) |
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| Abstract: | Songhu iron deposit is located at the western segment of Awulale metallogenic belt,which lies on the the northwest edge of Yili plate in West Tianshan,Xinjiang.The wall rocks are mainly andesite and andesitic volcaniclastic rocks of Lower Carboniferous Dahalajunshan Formation.The origin of this deposit is still controversial,and the focus is whether there is magmatic magnetite.In view of the above,the typomorphic characteristics of magnetite were carried out for various typical ores in Songhu iron deposit to constrain its ore genesis,and the trace element compositions of magnetite were analyzed by in-situ LA-ICP-MS.The results show that magnetites in disseminated and massive ores are typically high in contents of V,Ni and Ti,and low in contents of Al,Mn,Co,Zn and Sn,indicating similar geochemical characteristics with igneous magnetites;whereas magnetites in banded and brecciated ores have relatively high contents of Mg,Al,Mn and Zn,and low contents of V,which are approximate to hydrothermal magnetites in skarn deposit.The explosion temperature of magnetite inclusion indicates that there are two phases of inclusions in disseminated and massive ores,and their forming temperatures are 328℃-397℃and 424℃-485℃,respectively;the coarse-grained magnetites in banded and brecciated ores contain fewer inclusions that form at 343℃-385℃.Based on the typomorphic characteristics of magnetite,it is considered that the forming temperature of magnetites in disseminated ores is highest,that of magnetites in massive ores is higher,that of magnetites in brecciated ores is high,and that of magnetites in banded ores is low.This is also the forming order of these ores during the mineralization in Songhu iron deposit.Petrographical and trace element geochemical characteristics indicate that there are ore-magmas erupted during the early stage of mineralization in this deposit,and the hydrothermal magnetites are mainly formed by volcanic hydrothermal metasomatism rather than sedimentation.In conclusion,Songhu iron deposit genetically belongs to a volcanic magmatic-hydrothermal compound type. |
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| Keywords: | genesis of deposit iron deposit magnetite typomorphic characteristic trace element explosion temperature lattice parameter West Tianshan |
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