| 大兴安岭南段锡多金属矿床成矿岩体全岩地球化学、锆石U-Pb年龄、Hf同位素特征及其地质意义—以边家大院、毛登、宝盖沟矿床为例 |
| 投稿时间：2024-01-02 修订日期：2024-05-08 点此下载全文 |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目）92062218, 41672095 |
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| 中文摘要:大兴安岭南段是我国北方最重要的锡多金属成矿区。边家大院、宝盖沟和毛登锡多金属矿床是其中典型代表，其矿体均与燕山期花岗质侵入岩有密切的空间关系。对上述矿床含矿花岗侵入岩，即边家大院石英斑岩，宝盖沟花岗岩以及毛登花岗斑岩进行锆石U-Pb测定，结果显示成岩年龄分别为136.9±0.8Ma，143.6±0.8Ma和135.0±1.4Ma，均侵位于早白垩世。全岩主量元素分析显示，这些花岗侵入岩都具有高硅、钾和钠，低钙、镁和钛的特征，为准铝质-弱过铝质、高钾钙碱性花岗岩。微量元素分析显示花岗岩具有富集大离子亲石元素而亏损高场强元素的特征。稀土元素分析显示它们均具有明显的负Eu异常。根据全岩地球化学特征及锆石TZr温度（753°C~796°C）判断，这些花岗岩属于高分异I型花岗岩。研究表明三个岩体εHf(t)为-0.86~13.7，TDM2=307~1240Ma，锆石Hf同位素分析结果表明这些花岗岩主要为新元古代年轻地壳部分熔融形成。结合地球化学和地质年代学研究表明，大兴安岭南段早白垩纪高分异I型花岗岩具有较大的寻找锡矿的潜力 |
| 中文关键词:大兴安岭南段 锡矿 高分异花岗岩 早白垩世 |
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| Zircon U-Pb ages, whole-rock geochemistry and Hf isotope characteristics of ore-related intrusions in tin deposits, southern Great Xing`an and their geological significance |
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| Abstract:The southern Great Xing’an Range is the most important tin-polymetallic mineralization zone in Northern China, highlighted by the Bianjiadayuan, Baogaigou, and Maodeng deposits. These deposits are closely spatially associated with Yanshanian granitic intrusions. Precision zircon U-Pb isotopic dating of ore-bearing intrusions reveal emplacement ages of 136.9±0.8 Ma, 143.6±0.8 Ma, and 135.0±1.4 Ma for the Bianjiadayuan quartz porphyry, the Baogaigou granite, and the Maodeng granitic porphyry, respectively. According to detailed major element analyses, these granitic intrusions are classified as metaluminous to weak peraluminous, high-K calc-alkaline granites. Trace element studies show an enrichment in LILE and a depletion in HFSE of these intrusions, and they are characterized by pronounced negative Eu anomalies. We classified these granites as highly differentiated I-type granites, based on their whole-rock geochemical characteristics and Zr saturation temperature (753°C~796°C). Zircon Hf isotope analysis(εHf(t)=-0.86~13.7，TDM2=307~1240Ma) suggests that these granitic predominantly originated from partial melting of Neoproterozoic juvenile lower crust. Geochemical and geochronological studies suggest that early Cretaceous highly differentiated I-type granites in the southern Da Hinggan Range show significant potential for tin exploration. |
| keywords:Southern Greater Xing`an Tin deposits Highly fractionated granite Early Cretaceous |
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