| 内蒙古科右中旗地区梅勒图组安山岩年代学特征及其地质意义 |
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| 引用本文： | 金 玲,杨伟红,杨德明,和钟铧,马 瑞,王建国.内蒙古科右中旗地区梅勒图组安山岩年代学特征及其地质意义[J].世界地质,2014,33(1):48-58. |
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| 作者姓名： | 金 玲 杨伟红 杨德明 和钟铧 马 瑞 王建国 |
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| 作者单位： | 1. 吉林大学 地球科学学院，长春 130061; 2. 国土资源部中央地质勘查基金管理中心，北京 100045 |
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| 基金项目： | 中国地质调查局项目（1212010881214,1212010980044,1212011120648） |
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| 摘 要： | 对内蒙古科右中旗地区梅勒图组安山岩锆石LA--ICP--MS U--Pb年代学、锆石Hf同位素和岩石地球化学测试分析结果表明,梅勒图组安山岩形成时代约为早白垩世中期(123~125 Ma)。锆石εHf(t)=(+5.84~+9.34),一阶段Hf模式年龄为412~553 Ma。岩石地球化学分析表明,安山岩K2O含量较高,SiO2含量和Mg#值中等,富集大离子亲石元素,高场强元素Nb、Ta、Ti等明显亏损。这些特征反映出梅勒图组安山岩的源区为新形成的富集地幔。结合地球化学特征和区域大地构造背景,研究区梅勒图组安山岩的形成可能与太平洋板块俯冲作用后的陆内伸展环境有关。
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| 关 键 词： | 大兴安岭 梅勒图组 早白垩世 安山岩 锆石 U--Pb 年代学 |
Geochronology and geological significance of andesites from Meiletu Formation in Keyouzhongqi,Inner Mongolia |
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| JIN Ling,YANG Wei-hong,YANG De-ming,HE Zhong-hua,MA Rui,WANG Jian-guo.Geochronology and geological significance of andesites from Meiletu Formation in Keyouzhongqi,Inner Mongolia[J].World Geology,2014,33(1):48-58. |
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| Authors: | JIN Ling YANG Wei-hong YANG De-ming HE Zhong-hua MA Rui WANG Jian-guo |
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| Institution: | 1. College of Earth Sciences，Jilin University，Changchun 130061，China; 2. Manage Center of Central Geological Exploration Fund，Ministry of Land and Ｒesources，Beijing 100045，China |
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| Abstract: | The study of the LA-ICP-MS U-Pb dating,hafnium isotopic analyses of zircon,and geochemical analyses of the samples from Meiletu Formation in Keyouzhouqi of Inner Mongolia indicates that the Meiletu Formation formed at about the middle Early Cretaceous （123 ～ 125 Ma）.Their Hf isotopic analyses show that the εHf （t） ranges from ＋5.84 to ＋9.34 and the Hf single-stage model ages vary from 412 Ma to 553 Ma.Geochemical data of whole rocks show high content of K2O,moderate of SiO2 and Mg#,apparently enriched in LILEs and depleted in HFSEs,especially for Nb,Ta and Ti.These features imply that the source region of Meiletu Formation andesites is newly generated enriched-mantle.Combined the regional tectonic settings with characteristics of geochemistry,it is concluded that the andesites formed in the intra-continental extentional environment related to the subduction of Pacific Plate. |
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| Keywords: | Da-Hinggan mountains Meiletu Formation Early Cretaceous andesites zircon U-Pb chronology |
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