| 内蒙苏尼特右旗吉布胡楞土岩体LA-ICP-MS锆石U-Pb定年、地球化学特征及地质意义 |
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| 引用本文： | 李凤宪,白新会,万乐,关庆彬,李鹏川.内蒙苏尼特右旗吉布胡楞土岩体LA-ICP-MS锆石U-Pb定年、地球化学特征及地质意义[J].吉林大学学报(地球科学版),2015(2):429-440. |
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| 作者姓名： | 李凤宪 白新会 万乐 关庆彬 李鹏川 |
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| 作者单位： | 1. 天津市勘察院,天津,300191;2. 吉林大学地球科学学院,长春,130061 |
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| 基金项目： | 国家自然科学基金项目(41272223,41340024);中国地质调查局地质大调查项目(1212011120709,1212011220459,1212011085252) |
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| 摘 要： | 在华北板块北缘白乃庙岛弧岩浆活动带中发现了一套石榴石白云母花岗岩。锆石LA-ICP-MS U-Pb定年结果显示,该石榴石白云母花岗岩的结晶年龄为(500.8±2.4)Ma,为晚寒武世岩浆活动的产物。主量元素岩石地球化学特征方面:该岩体富硅、铝(w(SiO2)=72.50%~74.11%;w(Al2O3)=14.73%~16.43%),贫铁、镁、钙(w(TFeO)=0.67%~1.14%;w(MgO)=0.09%;w(CaO)=0.30%~0.61%),为高分异花岗岩(分异指数DI=91.99~93.20);铝饱和指数均大于1.1,发育富铝矿物石榴石和白云母,为过铝质花岗岩,但并非S型花岗岩;综合认为该石榴石白云母花岗岩是一套富铝、贫铁镁钙的高分异钙碱性I型花岗岩。微量元素特征方面:稀土总量较低,轻重稀土分馏不明显,具有强烈的负Eu异常;具明显的稀土元素四分组效应;并且部分岩石样品的Nb、Ta含量较高,暗示该岩体是分异岩浆与流体作用的产物。该岩体可为Nb、Ta等稀有金属成矿提供必要的物质基础。
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| 关 键 词： | 花岗岩 LA-ICP-MS 锆石 UPb 定年 地球化学 稀土元素四分组效应 高分异 |
Zircon LA ICP MS U Pb Dating,Geochemistry of the Jibuhulengtu Garnet-Bearing Muscovite Granitic Pluton in Mongolia and Its Geological Significance |
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| Li Fengxian
,
Bai Xinhui
,
Wan Le
,
Guan Qingbin
,
Li Pengchuan.Zircon LA ICP MS U Pb Dating,Geochemistry of the Jibuhulengtu Garnet-Bearing Muscovite Granitic Pluton in Mongolia and Its Geological Significance[J].Journal of Jilin Unviersity:Earth Science Edition,2015(2):429-440. |
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| Authors: | Li Fengxian Bai Xinhui Wan Le Guan Qingbin Li Pengchuan |
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| Institution: | Li Fengxian;Bai Xinhui;Wan Le;Guan Qingbin;Li Pengchuan;Tianjin Institute of Geotechnical Investigation & Surveying;College of Earth Sciences,Jilin University; |
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| Abstract: | There is a set of garnet-bearing muscovite granite in Bainaimiao island arc magmatic active belt that belongs to the northern part of the North China Craton.The Zircon LA ICP MS U Pb dating yields weighted mean 206 Pb/238 U age of (500.8 ± 2.4)Ma,indicating that the garnet-bearing muscovite granite was formed during the Late Cambrian.The petrogeochemistry is characterized by rich in Si,Al(w (SiO2 )=72.50% 74.1 1%,w (Al2 O3 )= 14.73% 1 6.43%)),poor in Fe,Mg and Ca (w (TFeO)= 0.67% 1.14%,w (MgO)= 0.09%,w (CaO)= 0.30% 0.61%).The garnet-bearing muscovite granite is highly differentiated with its DI of 91.99 93.20,the Shand Indexes of the garnet-bearing muscovite granitesare higher than 1.1,typical for high aluminum minerals,like garnet and muscovite. They are not S-type granite, but highly differentiated-Calc alkaline granite. The petrogeochemistry of rare earth element is characterized by low REE with strong depletion of Eu, showing a tetrad REE pattern.Some samples are rich in Nb,Ta,which indicates that the pluton was formed by magma differentiation and magma-fluid interaction.This pluton provided the necessary material foundation for other rare metal mineralization,such as Nb,Ta. |
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| Keywords: | granite Zircon LA ICP MS U Pb dating geochemistry REE tetrad pattern highly differentiated |
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