| 大兴安岭北段三根河林场新民组流纹岩锆石U－Pb定年及地球化学特征 |
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| 引用本文： | 李中会,李阳,李睿杰,李凯.大兴安岭北段三根河林场新民组流纹岩锆石U－Pb定年及地球化学特征[J].地质与资源,2020,29(4):310-318. |
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| 作者姓名： | 李中会 李阳 李睿杰 李凯 |
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| 作者单位： | 1. 黑龙江省地质调查研究总院, 黑龙江 哈尔滨 150036;2. 黑龙江省齐齐哈尔地质勘查总院, 黑龙江 齐齐哈尔 161006 |
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| 基金项目： | 中国地质调查局“内蒙古1：5万哈达岭、1254．9高地、三根河林场二段、三根河林场幅区域地质调查”（1212011220429）． |
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| 摘 要： | 三根河林场新民组火山岩主要由流纹岩、流纹质熔结凝灰岩组成，U－Pb定年结果表明流纹岩形成于165.71±0.83 Ma的中侏罗世.岩石地球化学分析结果显示，SiO2含量71.05%～76.77%，Na2O+K2O含量6.66%～8.49%，铝饱和指数（A/CNK）1.02～1.17，相对富硅、碱、过铝质，稀土元素总量中等，轻、重稀土元素分馏明显，具有较强的Eu负异常（δEu=0.39～0.66）和Dy负异常，大离子亲石元素Ba、Sr相对亏损，高场强元素Th、U相对富集，Nb、Dy、Ti相对亏损，岩石具有A型流纹岩的特征.岩石地球化学研究表明，岩浆来源于地壳物质的部分熔融作用.空间上，新民组沿大兴安岭火山岩带中北段均有分布，显示大兴安岭火山岩带于中侏罗世处于张性构造环境.
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| 关 键 词： | 新民组 流纹岩 锆石U－Pb年龄 地球化学 构造背景 大兴安岭 |
| 收稿时间： | 2019-09-25 |
ZIRCON U-Pb DATING AND GEOCHEMISTRY OF THE RHYOLITES FROM XINMIN FORMATION IN SANGENHE FOREST FARM,NORTHERN DAXINGANLING MOUNTAINS |
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| LI Zhong-hui,LI Yang,LI Rui-jie,LI Kai.ZIRCON U-Pb DATING AND GEOCHEMISTRY OF THE RHYOLITES FROM XINMIN FORMATION IN SANGENHE FOREST FARM,NORTHERN DAXINGANLING MOUNTAINS[J].Geology and Resources,2020,29(4):310-318. |
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| Authors: | LI Zhong-hui LI Yang LI Rui-jie LI Kai |
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| Institution: | 1. Heilongjiang Institute of Geological Survey, Harbin 150036, China;2. Qiqihar Institute of Geological Exploration, Qiqihar 161006, Heilongjiang Province, China |
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| Abstract: | The volcanic rocks of Xinmin Formation in Sangenhe forest farm are mainly composed of rhyolites and rhyolitic ignimbrites. The U-Pb dating results indicate the rhyolites were formed in Middel Jurassic, with the age of 165.71±0.83 Ma. The petrogeochemical analysis shows that the rhyolites are characterized by relatively high silicon, alkali and peraluminous, with the SiO2 content of 71.05%-76.77%, Na2O+K2O of 6.66%-8.49% and A/CNK of 1.02-1.17. The rocks present medium total REE content, significant fractionation of HREEs and LREEs, strong negative Eu anomaly (δEu=0.39-0.66) and negative Dy anomaly, relative depletion of LILEs (Ba and Sr), enrichment of HSFEs (Th and U) and relative depletion of Nb, Dy and Ti, with the characteristics of A-type rhyolites. The study shows the magma is derived from partial melting of crustal materials. The Xinmin Formation is spatially distributed along the middle-north section of Daxinganling volcanic belt, revealing the volcanic belt was in a tensional tectonic environment in Middle Jurassic. |
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| Keywords: | Xinmin Formation rhyolite zircon U-Pb age geochemistry tectonic setting Daxinganling Mountains |
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