| 西藏列廷冈铁多金属矿床磁铁矿元素地球化学特征及地质意义 |
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| 引用本文： | 李壮,唐菊兴,王立强,杨毅,钟毅.西藏列廷冈铁多金属矿床磁铁矿元素地球化学特征及地质意义[J].岩石矿物学杂志,2016,35(5):821-839. |
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| 作者姓名： | 李壮 唐菊兴 王立强 杨毅 钟毅 |
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| 作者单位： | 中国地质科学院 矿产资源研究所, 北京 100037;中国地质大学 地球科学与资源学院, 北京 100083;中国地质科学院 矿产资源研究所, 北京 100037;中国地质科学院 矿产资源研究所, 北京 100037;西藏自治区地质调查院, 西藏 拉萨 850000;重庆市地质矿产勘查开发局107地质队, 重庆 401120 |
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| 基金项目： | 中国地质调查局地质调查工作项目（12120113036200）；中央级公益性科研院所基本业务项目（K1416） |
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| 摘 要： | 西藏列廷冈矿床是林周盆地Fe-Mo-Cu-Pb-Zn矿集区内近年来新发现不久、规模较大的矽卡岩型铁多金属矿床。矿区磁铁矿发育,主要包括块状、浸染状和脉状3种类型。基于详细的野外地质调查和室内矿相学研究,将矿床成矿期划分为矽卡岩期和热液期2期,进而划分为5个成矿阶段:早期矽卡岩阶段、退化蚀变阶段、早期热液阶段、石英-硫化物阶段和碳酸盐阶段,其中,块状磁铁矿主要形成于退化蚀变阶段,浸染状和脉状磁铁矿主要形成于早期热液阶段。以磁铁矿为主要研究对象,采用电子探针(EPMA)和单矿物微量稀土元素ICP-MS分析实验,重点对磁铁矿元素地球化学特征、成因矿物学进行系统研究。研究结果表明,3种不同类型磁铁矿内均含Ti、Si、Ca等次要元素以及Na、K、Cr、Ni、Co、Pb、Ba、Sn、Sr、Sb、Cu等多种可检测到的微量元素,且矿物内主要发生了Al、Mg、Mn等元素的类质同像置换,综合TiO_2-Al_2O_3-MgO、TiO_2-Al_2O_3-(MgO+Mn O)和(Ca+Al+Mn)-(Ti+V)、Ni/(Cr+Mn)-(Ti+V)等多种磁铁矿成因判别图解投图结果及矿体野外宏观地质特征,表明矿区磁铁矿均为热液成因。块状磁铁矿具明显的Eu正异常,浸染状和脉状磁铁矿具Eu负异常,均无明显Ce异常特征,表明富Eu成矿流体在矽卡岩期的高温氧化环境下形成了矽卡岩型块状磁铁矿体,在热液期则逐渐转变为低温还原环境,形成浸染状和脉状磁铁矿及多种金属硫化物,且铁的物质来源主要与矿区花岗闪长岩和花岗斑岩紧密相关。
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| 关 键 词： | 地球化学 磁铁矿 电子探针 ICP-MS 列廷冈 西藏 |
| 收稿时间： | 2015/11/4 0:00:00 |
| 修稿时间： | 2016/4/8 0:00:00 |
Geochemistry of magnetites from the Lietinggang iron polymetallic deposit in Tibet and its geological significance |
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| LI Zhuang,TANG Ju-xing,WANG Li-qiang,YANG Yi and ZHONG Yi.Geochemistry of magnetites from the Lietinggang iron polymetallic deposit in Tibet and its geological significance[J].Acta Petrologica Et Mineralogica,2016,35(5):821-839. |
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| Authors: | LI Zhuang TANG Ju-xing WANG Li-qiang YANG Yi and ZHONG Yi |
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| Institution: | Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;School of Earth Science and Mineral Resources, Chinese University of Geosciences, Beijing 100083, China;Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Geological Survey of Tibet, Lhasa 850000, China;No. 107 Geological Party, Chongqing Bureau of Geological and Mineral Resource Prospecting & Development, Chongqing 401120, China |
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| Abstract: | The Lietinggang deposit is a newly discovered typical large-sized polymetallic deposit in the Fe-Mo-Cu-Pb-Zn ore concentration area of the Linzhou basin. There are mainly three types of magnetites in this mining area, i.e., massive, disseminated and veined magnetite. On the basis of detailed geological survey and systematic mineralogical studies, the metallogenic period of this deposit can be divided into two periods, i.e., skarn period and hydrothermal and supergene period, which include five ore-forming stages: early skarn stage, degradation and alteration stage, early hydrothermal stage, quartz-sulfide stage and carbonatization stage. The massive magnetite mainly formed at the degradation and alteration stage, whereas both the disseminated and veined magnetites formed at the early hydrothermal stage. In this study, the authors selected the magnetites as the main object of study and used electron microprobe analysis (EPMA) and rare earth trace elements ICP-MS experiments to gain an insight into the geochemical characteristics and minerageny of magnetites. The results show that three different types of magnetites (massive, veined and disseminated magnetites) contain Ti, Si, Ca and other minor elements such as Na, K, Cr, Ni, Co, Pb, Ba, Sn. In addition, a variety of trace elements like Sr, Sb and Cu can be detected. There are mainly Al, Mg and Mn replacing the other elements. Combining TiO2-Al2O3-MgO, TiO2-Al2O3-(MgO+MnO) and (Ca+Al+Mn)-(Ti+V), Ni/(Cr+Mn)-(Ti+V), and other discrimination diagrams with orefield geological characteristics, the authors have reached the conclusion that the magnetites of the Lietinggang deposit belong to hydrothermal magnetite. The massive magnetite has obvious positive Eu anomaly, the disseminated and veined magnetites show negative Eu anomaly, and they all have no significant Ce anomalies. The massive magnetites might have been formed in an environment of high oxidation and temperature with the fluids rich in Eu. At the hydrothermal stage, the fluids were gradually transformed into a low temperature and oxidation which could contribute to the formation of disseminated, veined magnetites and a large quantity of sulfides. Moreover, the main sources of iron materials were related to granodiorite and porphyry granite. |
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| Keywords: | geochemistry magnetite electron microprobe analysis ICP-MS Lietinggang Tibet |
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