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引用本文:宋哲,李厚民,李立兴,丁建华,孟洁. 新疆东天山黑尖山铁矿床富铁团块中磁铁矿的成分特征及岩浆-热液演化过程[J]. 中国地质, 2020, 47(3): 590-606.
SONG Zhe,LI Houmin,LI Lixing,DING Jianhua,MENG Jie. Magnetite compositions of the iron-rich agglomerates of the Heijianshan iron deposit in Eastern Tianshan Mountains and magmatic-hydrothermal evolution processes[J]. Geology in China, 2020, 47(3): 590-606(in Chinese with English abstract).
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新疆东天山黑尖山铁矿床富铁团块中磁铁矿的成分特征及岩浆-热液演化过程
宋哲1,2, 李厚民1, 李立兴1, 丁建华1, 孟洁3
1.自然资源部成矿作用与资源评价重点实验室/中国地质科学院矿产资源研究所, 北京 100037;2.地质过程与矿产资源国家重点实验室/中国地质大学 (武汉), 湖北 武汉 430074;3.中国地质调查局发展研究中心, 北京 100037
摘要:
黑尖山铁矿床是新疆东天山阿齐山—雅满苏成矿带中典型的海相火山岩型铁矿床。黑尖山矿床围岩安山质熔岩中发育大量不规则的富铁团块,可分为钠长石磁铁矿型、钠长石钾长石磁铁矿型、钾长石磁铁矿型、绿帘石磁铁矿型和石英磁铁矿型5种类型,可能代表了在岩浆-热液成矿过程中不同演化阶段的产物,对黑尖山铁矿床成矿过程及形成环境有指示意义。本文对上述5类富铁团块中的磁铁矿进行了主量元素分析,为了精确地测出磁铁矿中铁的总量,采用差分法加入不确定的O含量,并加以ZAF矩阵校正。对比5类富铁团块中磁铁矿Ti含量,钠长石磁铁矿型最高、钠长石钾长石磁铁矿型和钾长石磁铁矿型较高、绿帘石磁铁矿型和石英磁铁矿型最低,且Ti含量与Fe含量为正相关关系;绿帘石磁铁矿型和石英磁铁矿型富铁团块Fe含量特征与矿石中磁铁矿Fe含量相近。上述特征表明钠长石磁铁矿类型是残余富铁熔体中最早的结晶产物,钠长石钾长石磁铁矿和钾长石磁铁矿类型具有岩浆热液转变的特征,而绿帘石磁铁矿和石英-磁铁矿类型则是受热液完全交代的产物,说明矿床形成于岩浆-热液成矿作用。各类富铁团块内磁铁矿的Fe含量均大于相对应蚀变环边磁铁矿的Fe含量,表明富铁岩浆结晶与热液活动分异同期发生。
关键词:  海相火山岩型铁矿  黑尖山  富铁团块  岩浆-热液  矿产资源勘查工程  东天山
DOI:10.12029/gc20200303
分类号:P618.31
基金项目:中国地质调查局项目(DD20190606)和国家自然科学基金项目(41672078,41272102)联合资助。
Magnetite compositions of the iron-rich agglomerates of the Heijianshan iron deposit in Eastern Tianshan Mountains and magmatic-hydrothermal evolution processes
SONG Zhe1,2, LI Houmin1, LI Lixing1, DING Jianhua1, MENG Jie3
1.MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2.Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China;3.Development and Research Center of China Geological Survey, Beijing 100037, China
Abstract:
The Heijianshan iron deposit represents a typical submarine volcanic rock-hosted deposit of the Aqishan-Yamansu ore belt in Eastern Tianshan Mountains. Abundant irregular iron-rich agglomerates are developed in the brecciated andesite lava (wall rock), and they can be subdivided into five types, i.e., albite-magnetite type, albite-K-feldspar magnetite type, K-feldsparmagnetite type, epidote-magnetite type and quartz-magnetite type, likely representing evolving products of the magmatichydrothermal ore-forming process, which can constrain the ore-forming process and metallogenic environment of the Heijianshan iron deposit. Magnetite compositions of the five types of agglomerates were analyzed using electron microprobe analysis. For the purpose of obtaining precise Fe content, the content of undetermined O was added by difference method and the ZAF matrix correction was conducted. The Ti values of the five types of agglomerates display a positive relationship with the Fe values. Magnetite of the albite-magnetite type has highest Ti content, the albite-K-feldspar magnetite and the K-feldspar-magnetite types show medium Ti content, whereas the epidote-magnetite and quartz-magnetite types are characterized by the lowest Ti content. Also, the Fe content of the epidote-magnetite and the quartz-magnetite types is similar to that of the ores. These features indicate that the albite-magnetite type seems to have been the earliest crystallization product from a residual iron-rich melt, the albite-K-feldspar-magnetite and K-feldspar-magnetite types display features of magmatic-hydrothermal transition, whereas the epidote-magnetite and quartz-magnetite types represent products of hydrothermal alteration. The Fe content of magnetite of each type of agglomerate is higher than its content of the corresponding alteration zone, suggesting a simultaneous relationship between the crystallization of iron-rich agglomerates and hydrothermal activities.
Key words:  submarine volcanic rock-hosted iron deposit  Heijianshan  iron-rich agglomerates  magmatic-hydrothermal  mineral resources exploration project  Eastern Tianshan Mountains