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大兴安岭北段古利库金银矿区流纹岩年代学、岩石地球化学特征及地质意义

Geochronology,geochemical characteristics and geological significance of rhyolite in Guliku Gold Sliver Deposit,north part of Greater Khingan Mountains

  • 摘要: 古利库金银矿床是中国东北地区重要的浅成低温热液型金矿床之一,矿体主要赋存在流纹岩中。通过对古利库金银矿区流纹岩进行岩石地球化学和锆石U-Pb年代学研究,讨论了其岩石成因及构造背景。流纹岩锆石U-Pb年龄为(127.2±2.8)Ma,表明其喷出时代为早白垩世晚期,限定成矿时代应晚于该年龄。岩石地球化学分析结果显示:流纹岩具有明显的轻、重稀土元素分馏,富集大离子亲石元素Ba、Rb、Th、U等,亏损高场强元素Nb、P、Ti等。结合区域地质背景,认为流纹岩可能形成于早白垩世岩石圈大规模伸展减薄的动力学背景下,是地壳岩石部分熔融的产物。

     

    Abstract: The Guliku Gold Sliver Deposit is one of the important epithermal type gold deposits in Northeast China,and the ore bodies mainly host in rhyolite.Based on the analysis on geochemistry and zircon U-Pb dating of rhyolite in Guliku Gold Sliver Deposit,the petrogenesis and tectonic setting in this area are discussed.The zircon U-Pb dating of rhyolite yields age of (127.2±2.8)Ma,indicating that its extrusive age is late Early Cretaceous and the metallogenic epoch should be later.The analysis on geochemistry indicates that rhyolite has the evident characteristics of light and heavy rare earth fractionation,enrichment in large ion lithophile element(Ba,Rb,Th,U) and depletion in high field strength element(Nb,P,Ti).According to the regional geological setting,it can be considered that rhyolite of Guliku Gold Sliver Deposit results from partial melting of crustal rocks,and formed in dynamics setting of large-scale lithospheric extension-thinning in Early Cretaceous.

     

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