ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    华北中部狐偃山杂岩体形成时代研究——来自榍石U-Pb同位素年代学的证据

    Chronology Framework of Huyanshan Complex in Central North China Craton: Evidence from U-Pb Dating of Titanite

    • 摘要: 近年随着定年技术的发展,榍石LA-ICP-MS U-Pb定年法逐渐被学者采用,用来揭示某些特殊岩石类型的形成时代,如碱性岩。华北中部狐偃山碱性杂岩体由多个侵入体组成,岩性主要为二长岩类,岩石中发育大量继承锆石,结晶锆石相对较少,但包含大量岩浆榍石。本次研究即利用榍石LA-ICP-MS U-Pb定年法,对研究相对薄弱的矿泉、狼窝沟2个二长岩体中榍石进行了年代学分析。结果表明这2个二长岩体分别侵位于129 Ma和130 Ma。作为对比,同时对相同2个样品进行了锆石LA-ICP-MS U-Pb定年,2种方法得到的结果在误差范围内一致。结合前人研究资料,狐偃山杂岩体主体二长岩类侵位于早白垩世早期(127~131 Ma),早白垩世晚期(111~114 Ma)有少量正长岩形成,从而构成了狐偃山杂岩体。

       

      Abstract: With the development of dating technique, LA-ICP-MS U-Pb dating of titanite has been applied to some special rock types such as alkaline rocks. The Huyanshan alkaline complex was composed of several plutons; the major lithology was monzonite with abundant inherited zircons and magmatic titanites, and little crystallized zircons. This study analyzed chronologically the two monzonites of Kuangquan and Langwogou based on the LA-ICP-MS U-Pb dating of titanite. Results show that the two were emplaced at 129~130Ma. Meanwhile zircon LA-ICP-MS U-Pb dating was conducted on the same two samples as a contrast. The two dating techniques are consistent within the error range. According to previous studies, Monzonites of the main part of Huyanshan complex were emplaced in the early Early Cretaceous (127~131 Ma), while small amount of syenites were formed in the late Early Cretaceous(111~114 Ma),eventually forming the Huyanshan complex.

       

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