地学前缘 ›› 2018, Vol. 25 ›› Issue (5): 183-201.DOI: 10.13745/j.esf.sf.2018.4.1

• 中亚造山带地质事件与成矿 • 上一篇    下一篇

大兴安岭南段维拉斯托锡多金属矿床LA-ICP-MS锡石和锆石U-Pb年龄及其地质意义

刘瑞麟，武广，李铁刚，陈公正，武利文，章培春，张彤，江彪，刘文元   

  1. 1. 中国地质科学院 矿产资源研究所 国土资源部成矿作用与资源评价重点实验室, 北京100037
    2. 北京大学 造山带与地壳演化教育部重点实验室, 北京 100871
    3. 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    4. 内蒙古自治区地质调查院, 内蒙古 呼和浩特 010020
    5. 福州大学 紫金矿业学院 福建省矿产资源重点实验室, 福建 福州 350108
  • 收稿日期:2018-02-08 修回日期:2018-03-09 出版日期:2018-09-15 发布日期:2018-09-15
  • 作者简介:刘瑞麟(1988—)，男，博士研究生，主要从事矿床学研究工作。E-mail:liuruilin@pku.edu.cn
  • 基金资助:
    内蒙古自治区地质勘查基金项目(2015-01-YS01)；国家自然科学基金项目(41772086)

LA-ICP-MS cassiterite and zircon U-Pb ages of the Weilasituo tin-polymetallic deposit in the southern Great Xing an Range and their geological significance

LIU Ruilin,WU Guang,LI Tiegang,CHEN Gongzheng,WU Liwen,ZHANG Peichun,ZHANG Tong,JIANG Biao,LIU Wenyuan   

  1. 1. MRL Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chines Academy of Geological Sciences, Beijing 100037, China
    2. MOE Key Laboratory of Orogenic Belts and Crustal Evolution, Peking University, Beijing 100871, China
    3. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    4. Inner Mongolia Institute of Geological Survey, Hohhot 010020, China
    5. Fujian Key Laboratory of Mineral Resources, Zijin College of Mining, Fuzhou University, Fuzhou 350108, China
  • Received:2018-02-08 Revised:2018-03-09 Online:2018-09-15 Published:2018-09-15

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摘要：

维拉斯托锡多金属矿床位于大兴安岭南段西坡的内蒙古克什克腾旗，是近年来发现的一个以锡为主，共伴生钨、锌、铜、钼、铷、铌和钽的大型矿床。矿化类型包括深部以锡为主，伴生锌、铷、铌和钽的蚀变花岗岩型矿体；中部以锡为主，伴生铜和锌的隐爆角砾岩型矿体及浅部锡、钨、锌、铜和钼的石英大脉型和网脉型矿体。该矿床的主要工业矿体为石英脉型，呈北北东向产于古元古界宝音图群和华力西期石英闪长岩中的断裂破碎带内，而蚀变花岗岩型和隐爆角砾岩型矿石的品位较低。文中选取1件石英脉型锡矿体中的锡石样品进行了LA-ICP-MS锡石U-Pb定年，获得锡石的206Pb/207Pb238U/207Pb等时线年龄为(136.0±6.1) Ma(MSWD=0.94)，207Pb/206Pb238U/206Pb谐和年龄为(132.3±5.4) Ma(MSWD=2.8)，表明维拉斯托锡多金属矿床形成于早白垩世；选取1件与成矿相关的北大山岩体花岗岩样品开展了LA-ICP-MS锆石U-Pb定年，获得206Pb/238U年龄为(140±2) Ma(MSWD=0.10)，表明成矿岩体亦形成于早白垩世。维拉斯托锡多金属矿床属于与花岗岩有关的岩浆热液型矿床。通过统计大兴安岭南段主要锡多金属矿床的成矿年龄和成矿岩体的年龄，发现几乎所有的锡多金属矿床均形成于140～135 Ma期间，表明早白垩世是大兴安岭南段锡多金属矿床成矿高峰期。

关键词: 锡石U-Pb年龄, 锆石U-Pb年龄, 维拉斯托锡多金属矿床, 内蒙古, 大兴安岭南段

Abstract: The Weilasituo tin-polymetallic deposit, located in Hexigten Banner of Inner Mongolia, is a newly discovered large tin deposit associated with tungsten, zinc, copper, molybdenum, rubidium, niobium and tantalum the west slope of the southern Great Xingan Range. Three types of mineralization developed in the deposit: the deep section altered granite-type orebody is dominated by Sn and associated with Zn, Rb, Nb; the middle section cryptoexplosive breccia-type orebody is mainly of Sn with Cu and Zn; and the shallow section comprises quartz vein-type Sn, W, Zn, Cu, and Mo ore bodies. The quartz vein-type ore bodies are the most economically valuable ores, they are hosted within the NNE-trending shattered fault zones of the Paleoproterozoic Baoyintu Group and Middle Variscan quartz diorite, whereas the altered granite- and cryptoexplosive breccia-type ore bodies are usually low grade ores. A cassiterite sample from the quartz vein-type Sn ore of the Weilasituo deposit was selected for LA-ICP-MS dating, which yielded a 206Pb/207Pb238U/207Pb isochron age of 136.0±6.1 Ma (MSWD=0.94) and a 207Pb/206Pb238U/206Pb concordant age of 132.3±5.4 Ma (MSWD=2.8). The result suggested that the Weilasituo Sn-polymetallic mineralization took place during the Early Cretaceous. A zircon sample from the Beidashan granite was also selected for LA-ICP-MS dating, and the result of a weighted mean 206Pb/238U age of 140±2 Ma (MSWD=0.10) indicated the ore causative intrusion also formed during the Early Cretaceous. The Weilasituo tin-polymetallic deposit belongs to a granite-related magmatic-hydrothermal deposit. Our dating results, together with previous researchers rock- and ore-forming ages of other Sn-polymetallic deposits in the southern Great Xingan Range, demonstrated that almost all Sn-polymetallic deposits formed during 140135 Ma, which suggests that the Early Cretaceous is the peak era for the formation of the Sn-polymetallic deposits in the southern Great Xingan Range.

Key words: cassiterite U-Pb age, zircon U-Pb age, Weilasituo tin-polymetallic deposit, Inner Mongolia, southern Great Xingan Range

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