| 福建平和矾山地区花岗岩地球化学、年代学、Hf同位素特征及地质意义 |
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| 引用本文： | 王森,张达,赵红松,潘天望,吕良冀,冯海滨,狄永军. 福建平和矾山地区花岗岩地球化学、年代学、Hf同位素特征及地质意义[J]. 地球科学, 2016, 41(1): 67-83. DOI: 10.3799/dqkx.2016.005 |
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| 作者姓名： | 王森 张达 赵红松 潘天望 吕良冀 冯海滨 狄永军 |
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| 作者单位： | 中国地质大学地质过程与矿产资源国家重点实验室，北京 100083 |
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| 基金项目： | “武夷山植被覆盖区成矿地质背景研究与成矿要素综合推断”项目1212011085472中国地质调查局“武夷山植被覆盖区勘查模型研究与控矿要素探查”项目12120113089600福建龙岩马坑-大田汤泉铁矿整装勘查区专项填图与技术应用示范”项目12120114028701 |
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| 摘 要： | 为了揭示矾山地区中生代花岗岩的成因、侵位时间及其与成矿的关系，在岩石地球化学研究基础上，进行锆石U-Pb-Hf同位素测试，并与紫金山矿田进行对比，为本区找矿预测提供依据.矾山地区花岗岩具有高钾、高碱、富硅、低钛等特征，富集轻稀土元素，具弱-中等负铕异常.富集大离子亲石元素(K、Rb、Th等)，亏损高场强元素(Nb、Ta、Ti等)，具有板块俯冲后伸展环境特征.对花岗岩岩体进行锆石U-Pb测年，获得了110 Ma的年龄.花岗岩与花岗闪长岩Hf同位素特征相似，εHf(t)为-3.1~1.6，TDM2为1 066~1 366 Ma，说明花岗岩主要来源于中元古代地壳物质的重融，同时显示出壳幔混合作用的特征.矾山地区与紫金山矿区构造、成岩、成矿特征相似，具有“紫金山式”铜金矿找矿潜力.
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| 关 键 词： | 大小矾山 锆石U-Pb Hf同位素 紫金山 岩石学 |
| 收稿时间： | 2015-09-30 |
Geochemistry,Zircon U-Pb Dating and Hf Isotope Composition of Granite in Fanshan Area,Pinghe County,Fujian Province,and Its Geological Significance |
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| Abstract: | In order to study the chronological and geochemical characteristics of the Mesozoic granite and granodiorite from Fanshan area and their relationship with the regional mineralization, the LA-MC-ICPMS zircons U-Pb dating method was employed to assess the ages and Hf isotope composition, preceded by their petrological and geochemical studies. In addition, the authors aim to provide more evidences that will facilitate the next phase of prospecting by making a comparison with Zijinshan copper-gold ore field. The metaluminous-peraluminous high-K calcalkaline granite series and granodiorite are characterized by high contents of K2O, SiO2, and low TiO2. These samples are enriched in light rare earth element (LREE) and large ionic lithophile elements (LILE, e.g. K, Rb, Sr, Cs), but depleted in high strength elements (HFSE, e.g. Nb, Ta, Zr, Ti), and have negative Eu anomalies. The geochemical properties of granite and granodiorite are similar to those of the magmatic arc rocks, which suggest a backarc spreading setting. The zircon U-Pb dating of two representative samples yield an emplaced age of 110 Ma, in Early Cretaceous. Zircon grains from the granites have lower Hf-isotpe compositions with εHf(t)=-3.1-1.6 and younger Hf model ages (TDM2)=1 066-1 366 Ma. In comparison with the metamorphic basement near the study area, we suggest that the granitic rocks are probably derived from a Mesoproterozoic crust, but the granodiorite may have originated from a Mesoproterozoic crust-mixed with a fraction of mantle materials. Based on the comparative study with Zijinishan Orefield, it is concluded that there are similar structural, lithogeneous and metallogenic features between the two areas, and there is huge prospecting potential to find "Zijinshan style" copper-gold polymetallic deposits in Fanshan area. |
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