投稿时间：2015-06-27
修订日期：2016-04-22
网络发布日期：2016-06-30
中文摘要:内蒙古火龙沟铅锌矿床是近期勘查发现、预期可达中型规模以上的铅锌矿床之一,笔者对该矿区的侵入岩——正长花岗岩进行了LA-MC-ICP-MS锆石U-Pb定年和主量、微量元素分析,锆石U-Pb定年结果为(224.0±2.5) Ma,表明,该岩体侵位于晚三叠世。岩石地球化学研究结果显示火龙沟正长花岗岩体具有明显富SiO2和ALK、贫MgO和TFe的特点,A/NK-A/CNK图解显示正长花岗岩属于准铝质花岗岩。微量元素蛛网图显示富集大离子亲石元素Rb、Th、U、K,亏损高场强元素Nb、Ta、Ti。稀土元素配分模式表现出富集LREE,亏损HREE的右倾型,LREE/HREE=8.04~10.40,具有明显Eu的负异常。花岗岩锆饱和温度计算结果表明该花岗岩岩浆形成温度为820℃,属于高温花岗岩,以上地球化学特征和高温的特点表明该花岗岩为A型花岗岩。结合区域构造演化历史,笔者认为该花岗岩体形成于古亚洲洋闭合后的造山后垮塌岩石圈伸展构造环境。
Abstract:A new lead-zinc ore deposit was recently discovered in Huolonggou of Inner Mongolia. Chronologic and geochemical research was carried out on intrusions in this region. The LA-MC-ICP-MS zircon U-Pb dating result of the granite intrusive is (224.0±2.5)Ma, suggesting that the granite was intruded in late Triassic. Geochemically, the values of major elements indicate that this granite is characterized by rich SiO2 and alkali and poor MgO and Fe. In a plot of A/NK versus A/CNK, the rocks belong to metaluminous type. In the spider diagrams of rare elements, the rocks are obviously rich in large lithophile elements, especially rich in Rb, Th, U and K, but poor in Nb, Ta and Ti. REE distribution curve is significantly rightly oblique. LREE/HREE ratios range from 8.04 to 10.40 with apparent negative Eu anomalies. Using zircon saturation thermometer,the authors calculated the formation temperature of this granite and the results show that most of the rocks exceed 800℃, with an average value of 820℃. Such a high crystallization temperature and geochemical characteristics indicate that this granite belongs to A-type granite. Combined with the regional tectonic evolution history, the authors hold that the formation of this A-type granite in the Huolonggou ore deposit was related to the post-orogenic process, most probably due to lithospheric delamination.
keywords:geochemistry intrusion zircon U-Pb dating LA-MC-ICP-MS tectonic setting Huolonggou ore deposit Inner Mongolia
文章编号：
中图分类号：P618.42;P618.43
文献标志码：
基金项目:本文得到地质调查项目(编号:12120115069901)、(编号:12120113090100)和国家重点基础研究发展计划(编号:2013CB429803)联合资助
引用文本：
杨文生,佘宏全,席文泽,康永建,向安平,李进文,李长俭,赵迎磊.2016.内蒙古火龙沟铅锌矿床成矿岩体年代学、地球化学及其地质意义[J].矿床地质,35(3):509~523YANG WenSheng,SHE HongQuan,XI WenZe,KANG YongJian,XIANG AnPing,LI JinWei,LI ChangJian,ZHAO YingLei.2016.Geochronology and geochemistry of syenogranite in Lead-zinc Huolonggou deposit of Inner Mongolia and its geological implications[J].Mineral Deposits35(3):509~523
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