地学前缘 ›› 2015, Vol. 22 ›› Issue (3): 348-356.DOI: 10.13745/j.esf.2015.03.030

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内蒙古东珺铅锌银矿床闪锌矿Rb-Sr定年及其地质意义

杨郧城, 郭万军, 王亚君, 佘宏全, 李进文, 张斌   

  1. 中国地质科学院 矿产资源研究所, 北京 100037; 内蒙古自治区地质勘查局 第六地质矿产勘查开发院, 内蒙古 海拉尔 021000
  • 收稿日期:2013-07-30 修回日期:2013-12-13 出版日期:2015-05-15 发布日期:2015-05-15
  • 作者简介:杨郧城(1965—)，男，副研究员，地球化学专业。E-mail:yangyuncheng@sina.com
  • 基金资助:

    国家重点基础研究发展计划“973”项目(2013CB429803);中国地质调查局地质调查项目(12120113090100)

RbSr dating of sphalerites from Dongjun PbZnAg deposit, Inner Mongolia and its geological significance.

 YANG  Yun-Cheng, GUO  Mo-Jun, WANG  E-Jun, SHE  Hong-Quan, LI  Jin-Wen, ZHANG  Bin   

  • Received:2013-07-30 Revised:2013-12-13 Online:2015-05-15 Published:2015-05-15

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摘要：

热液脉型铅锌多金属矿床是内蒙古得尔布干成矿带一重要矿床类型，由于缺乏适当的定年方法，该类矿床的成矿年龄及其形成的地质背景一直不明确。东珺铅锌银矿床是一新近发现的热液脉型矿床，本文在对采自该矿床的6件闪锌矿矿石样品进行了结构构造研究的基础上，对闪锌矿的RbSr同位素进行了分析。结果表明，闪锌矿87Rb/86Sr和87Sr/86Sr同位素比值均有较大的分布范围，分别分布在0.283 8~6.503 0和0.713 685~0.725 241范围内，二者具有很好的线性关系，构成的等时线年龄为(130.2±4.4) Ma(2σ,MSWD=16),(87Sr/86Sr)0=0.713 176±0.000 057，指示矿床形成于早白垩世。早白垩世大兴安岭地区处于伸展构造体制，因此该类矿床是在拉张构造体制的背景下形成的，与区内早白垩世浅成超浅成岩浆侵入活动有关，它代表了区内一重要成矿阶段与成矿类型。

关键词: 东珺铅锌银矿床, 闪锌矿, Rb-Sr同位素年龄

Abstract:

Hydrothermal vein type of PbZn polymetallic ore deposits is one kind of important deposit in Deerbugan meatallogenic zone, Inner Mongolia, China. Their oreforming ages and geological backgrounds are still unclear. Six pieces of sphalerites collected from Dongjun hydrothermal vein type of PbZnAg deposits were analyzed for Rb, Sr and their isotopes. The 87Rb/86Sr and 87Sr/86Sr ratios fall into the ranges of 0.2838 to 6.5030 and 0.713685 to 0.725241, respectively, and they show good linear relationship, defining a RbSr age of 130.2±4.4 Ma (2σ, MSWD=16), (87Sr/86Sr)0=0.713176±0.000057, indicating that the mineralization age of Dongjun PbZnAg deposit is in the Early Cretaceous. As the Da Hinggan Mountains and its adjacent region were in an extensional setting in the early Cretaceous, so this type of ore deposit was formed in an extensional tectonic regime in the early Cretaceous, and its mineralization was related to hypabyssalultra hypabyssal magmatic intrusion. This type of ore deposit represents an important metallogenic period and type in the Deerbugan metallogenic belt.

Key words: Dongjun PbZnAg deposit, sphalerites, RbSr age

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