欢迎访问现代地质!

现代地质 ›› 2021, Vol. 35 ›› Issue (02): 466-476.DOI: 10.19657/j.geoscience.1000-8527.2021.038

• 岩石学 • 上一篇    下一篇

冈底斯西段麻木矽卡岩型铅锌矿化区岩浆岩锆石U-Pb年龄及地质意义

刘畅1(), 杨竹森2(), 徐培言1, 赵晓燕2, 夏文杰1, 杨晓旭1   

  1. 1.中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2.中国地质科学院矿产资源研究所,北京 100037
  • 收稿日期:2021-01-06 修回日期:2021-03-01 出版日期:2021-04-25 发布日期:2021-05-25
  • 通讯作者: 杨竹森
  • 作者简介:杨竹森,男,研究员,1964年出生,成因矿物学专业,主要从事矿床学与矿物地球化学研究。Email: yangzhusen@vip.sina.com
    刘 畅,男,硕士研究生,1996年出生,地质工程专业,主要从事成因矿物与找矿矿物研究。Email: 2101180044@cugb.edu.cn
  • 基金资助:
    国家重点研发计划项目(2016YFC0600306);中国地质调查局地质调查项目(DD20179172);国家自然科学基金项目(42072107)

Zircon U-Pb Age of Granitoids from the Mamu Pb-Zn Skarn Mineralized Area in Western Gangdese and Its Geological Significance

LIU Chang1(), YANG Zhusen2(), XU Peiyan1, ZHAO Xiaoyan2, XIA Wenjie1, YANG Xiaoxu1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083,China
    2. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037,China
  • Received:2021-01-06 Revised:2021-03-01 Online:2021-04-25 Published:2021-05-25
  • Contact: YANG Zhusen

摘要:

西藏革吉麻木铅锌矿化区是中冈底斯成矿带(中拉萨地块)西段南缘近年发现的一个矽卡岩型铅锌矿化区,矿化产于花岗斑岩与灰岩外接触带的矽卡岩内。金属矿物有方铅矿、闪锌矿、磁铁矿、镜铁矿、黄铁矿;脉石矿物有石榴子石、透辉石、蔷薇辉石、阳起石、绿帘石、石英、长石、方解石;蚀变包括硅化、黏土化、大理岩化、绿泥石化;赋矿围岩是捷嘎组灰岩。为对其成岩成矿时代进行年代学约束,对花岗斑岩、晶屑凝灰岩的锆石进行了LA-ICP-MS U-Pb同位素定年,结果显示花岗斑岩的时代为(117.6±0.4) Ma,表明与花岗斑岩侵入活动相关的矽卡岩型铅锌矿化时代属于早白垩世;晶屑凝灰岩的时代为(119.7±0.5) Ma,归属于则弄群(J3K1Z),而不应归入《1:25万亚热幅地质图》上所填的典中组(E1d)。结合前人研究成果,麻木研究区发生的早白垩世中酸性岩浆喷发和侵入活动,其深部地球动力学背景可能主要受控于班公湖—怒江缝合带向南俯冲。麻木铅锌矿化点作为早白垩世铅锌矿化事件,对于补充冈底斯金属成矿带西段铅锌成矿作用研究以及完善多期铅锌成矿事件的认识具有重要意义。

关键词: 锆石U-Pb年龄, 早白垩世岩浆活动, 铅锌矿化, 冈底斯成矿带西段

Abstract:

The Mamu area in Gakyi, Tibet,China is a Pb-Zn skarn mineralized zone discovered in recent years. The area is located on the southern margin of the western central Gangdese metallogenic belt (or the central Lhasa terrane). Mineralization occurred in the contact zone between granite porphyry and limestone. Metallic minerals include galena, sphalerite, magnetite, specularite, and pyrite, whilst non-metallic ones include garnet, diopside, rhodonite, actinolite, epidote, quartz, feldspar, and calcite. Alteration styles include silicic, argillic, marl, and chlorite. The mineralization is hosted in the Jiega Formation (Fm.) limestone. To obtain geochronological constraints on the magmatism and mineralization, the granite porphyry is LA-ICP-MS zircon U-Pb dated to be (117.6±0.4) Ma, which shows that ore-causative porphyry was emplaced in the Early Cretaceous. The age of crystal lithic tuff is (119.7±0.5) Ma, and the tuff should thus belong to the Zenong Group (J3K1Z) instead of the Dianzhong Formation (E1d) in the 1∶250,000 Yagra Geologic Map Sheet. The study area experienced intense medium-felsic volcanism and plutonism in the Early Cretaceous. Combined with previous studies, the deep geodynamic background was mainly controlled by the south-dipping subduction of the Bangong-Nujiang Suture Zone. As an Early Cretaceous Pb-Zn mineralization event, the Mamu Pb-Zn prospect is of great significance to supplement the study of regional Pb-Zn mineralization and to improve our understanding on multi-phase Pb-Zn metallogenic events.

Key words: zircon U-Pb age, Early Cretaceous magmatism, Pb-Zn mineralization, western Gangdese metallogenic belt

中图分类号: