投稿时间：2015-09-12
修订日期：2016-06-21
网络发布日期：2016-08-25
中文摘要:雷门沟钼矿床是东秦岭地区典型的斑岩型矿床之一。矿体主要赋存于雷门沟花岗斑岩体内，部分产于岩体外接触带的太华群片麻岩中。LA-（MC）-ICP-MS锆石U-Pb定年结果显示，雷门沟花岗斑岩的成岩年龄为（131.0±0.6）Ma（n=25，MSWD=1.6），与辉钼矿Re-Os同位素年龄（132±2）Ma一致。岩石地球化学分析表明，该岩体的A/CNK=1.11~1.17，w（K2O+Na2O）为8.12%~9.07%，K2O/Na2O比值为1.17~1.68，属于过铝质和高钾钙碱性系列。稀土和微量元素特征显示，该岩体富集LREE、K、Rb、Ba、Sr、Pb等大离子亲石元素，亏损HREE、Nb、Ta、Ti、P等高场强元素，具有中等的负铕异常。岩石的初始87Sr/86Sr比值为0.709 319~0.709 326，εNd（t）值为-16.26~-16.16；锆石的εHf（t）值变化于-27.9~-16.9，二阶段模式年龄tDM2=2259~2946 Ma，显示其源区物质以壳源物质为主，可能为太古宙太华群，有少量幔源组分的参与，岩体可能是由底侵的基性幔源岩浆诱发的地壳物质部分熔融形成的。与邻近的花山岩基的地球化学和同位素特征对比表明，雷门沟花岗斑岩和花山岩基来源于相同的源区，推测二者应是不同侵入期次的产物。
Abstract:The Leimengou Mo deposit is one of the typical porphyry deposits in the East Qinling orogenic belt. The Mo mineralization is mainly hosted in the Leimengou granite porphyry and surbodinately in the gneiss of Archean Taihua Group in the external contact zone. Zircon U-Pb LA-(MC)-ICP-MS dating yielded (131.0±0.6) Ma (n=25, MSWD=1.6), corresponding to (132±2) Ma of Mo mineralization age obtained by the Re-Os method. The Leimengou granite porphyry is of peraluminous and high-K calc-alkaline series with the data A/CNK=1.11~1.17,w(K2O+Na2O)=8.12%~9.07% and K2O/Na2O=1.17~1.68. The REE and trace elements characteristics show enrichment of large ion lithophile elements (LREE, K, Rb, Ba, Sr and Pb) and depletion of high-field strength elements (HREE, Nb, Ta, Ti and P), with moderately negative anomaly of Eu. The rocks have initial 87Sr/86Sr ratios of 0.709 319~0.709 326 and εNd(t) values of -16.26~-16.16. The granite porphyry shows a large variation in zircon Hf compositions with εHf(t) values of -27.9~-16.9 and two-stage model ages of 2259~2946 Ma. Geochemistry and Sr-Nd-Hf isotopic compositions suggest that the Leimengou granite porphyry was derived mainly from an ancient continental crust (probably Archean Taihua Group), with the addition of mantle related materials. Therefore, the formation of Leimengou granite porphyry could be interpreted as partial melting of the old crust induced by an underplated mantle-derived magma. According to geochemical and isotopic data, the Leimengou granite porphyry and the adjacent Huashan granitic batholith may share the same magmatic source, and both are products of an independent magmatic activity.
keywords:geochemistry zircon U-Pb dating Sr-Nd-Hf isotope granite porphyry Leimengou southern margin of the North China Block
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中图分类号：P618.65
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基金项目:本文得到国家自然科学基金项目（编号：41272104）和地质调查项目（编号：1212011220869）联合资助
引用文本：
曹晶,叶会寿,陈小丹,李正远,张兴康,贺文.2016.豫西雷门沟钼矿区花岗斑岩年代学、地球化学和Sr-Nd-Hf同位素研究[J].矿床地质,35(4):677~695CAO Jing,YE HuiShou,CHEN XiaoDan,LI ZhengYuan,ZHANG XingKang,HE Wen.2016.Geochronology, geochemistry and Sr-Nd-Hf isotopic compositions of granite porphyry in Leimengou Mo deposit, western Henan Province[J].Mineral Deposits35(4):677~695
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