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现代地质 ›› 2025, Vol. 39 ›› Issue (04): 1016-1038.DOI: 10.19657/j.geoscience.1000-8527.2024.119

• 矿床学与岩石学 • 上一篇    下一篇

滇东南白牛厂隐伏二长花岗岩岩石成因及对银多金属成矿作用的指示:来自地球化学、U-Pb年代学和Hf同位素的约束

米雪1(), 刘学龙1,*(), 张世涛1, 陈书富2, 蒙光志2, 张红3, 程家龙4, 周杰虎1, 陆波德1, 刀俊山2, 史楠1, 范茂煌2   

  1. 1.昆明理工大学国土资源工程学院, 云南 昆明 650093
    2.云南省有色地质局306队,云南 昆明 650217
    3.蒙自矿冶有限责任公司, 云南 红河 661100
    4.云南省地质矿产勘查院,云南 昆明 650051
  • 出版日期:2025-08-10 发布日期:2025-08-27
  • 通信作者: *刘学龙,男,博士,教授,博士生导师,1983年出生,主要从事云南三江地区的地质矿产研究及矿床学教学工作。Email:xuelongliu@foxmail.com
  • 作者简介:米雪,女,硕士研究生,1999年出生,主要从事矿床地球化学研究工作。Email:mx13283599622@163.com
  • 基金资助:
    昆明理工大学“双一流”科技专项课题(202202AG050006-2);国家自然科学基金项目(42362010);云南省高层次科技人才及创新团队选拔专项(202305AT350004-4);云南省三江成矿系统与评价顶尖团队培育项目(202305AS350015)

Petrogenesis of the Concealed Monzogranite in the Bainiuchang Ag-polymetallic Deposit, Southeastern Yunnan, and Its Implications for Ag-polymetallic Mineralization: Constraints from U-Pb Geochronology, Geochemistry, and Hf Isotopes

MI Xue1(), LIU Xuelong1,*(), ZHANG Shitao1, CHEN Shufu2, MENG Guangzhi2, ZHANG Hong3, CHENG Jialong4, ZHOU Jiehu1, LU Bode1, DAO Junshan2, SHI Nan1, FAN Maohuang2   

  1. 1. School of Land Resources Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China
    2. No.306 Geological Team, Yunnan Nonferrous Metals Geological Bureau, Kunming, Yunnan 650217, China
    3. Mengzi Mining and Metallurgy Co., Ltd., Honghe, Yunnan 661100, China
    4. Yunnan Institute of Geology and Mineral Resources Exploration, Kunming, Yunnan 650051, China
  • Published:2025-08-10 Online:2025-08-27

摘要:

白牛厂银多金属矿床是滇东南地区超大型矿床之一,位于滇东南地区薄竹山西北部。本文在系统的野外工作基础上对白牛厂隐伏二长花岗岩进行了LA-ICP-MS锆石U-Pb定年、全岩地球化学与锆石Lu-Hf同位素测试,确定深部隐伏花岗岩的形成时代、成因、岩浆来源及蚀变影响,结合构造背景,分析白牛厂隐伏花岗岩岩体与成矿作用。研究结果表明,白牛厂二长花岗岩4件样品锆石U-Pb年龄分别为(87.7±0.5) Ma、(87.34±0.4) Ma、(88.5±0.5) Ma、(87.1±0.5) Ma,均属燕山晚期。白牛厂二长花岗岩具富硅(SiO2含量为66.27%~73.77%)、富碱(Na2O+K2O含量为6.17%~8.48%)特征,具有较高的稀土元素含量(ΣREE=172.49×10-6~333.22×10-6,平均值271.30×10-6),轻重稀土元素分馏明显(LREE/HREE=12.74~20.47,平均值16.76),具弱的负铕异常(0.44~0.78),相对富集大离子亲石元素Rb、K和高场强元素Th、U、Ce、Zr、Hf、Ta等,属过铝质的高钾钙碱性S型花岗岩。白牛厂二长花岗岩的锆石εHf(t)值为-21.5~-4.3,对应的Hf二阶段模式年龄为1259~1614 Ma,表明其岩浆来源于中—新元古代古老地壳物质的熔融。综合分析认为,白牛厂断层F3的形成,为研究区深部岩浆活动提供了运移通道及空间,花岗质岩浆的上涌带来锡、铜、锌等多种成矿元素,随之固结形成深部隐伏花岗岩岩体,白牛厂深部隐伏二长花岗岩体形成与燕山晚期区域上同碰撞造山向碰撞后造山的构造背景转换联系密切。

关键词: 锆石U-Pb定年, LA-ICP-MS, 二长花岗岩, 深部隐伏花岗岩岩体, 白牛厂

Abstract:

The Bainiuchang silver polymetallic deposit, one of the super-large deposits in southeastern Yunnan, is located in the northwestern part of Bozhu Mountain, southeastern Yunnan. Based on systematic fieldwork, this study conducted LA-ICP-MS zircon U-Pb dating, whole-rock geochemical analysis, and zircon Lu-Hf isotope analysis on the concealed monzogranite in Bainiuchang to determine the formation age, genesis, magma source, and alteration effects of the deep concealed granite. Combined with the tectonic setting, the relationship between the concealed granite and mineralization was analyzed. The results show that the zircon U-Pb ages of four monzogranite samples from Bainiuchang are (87.7±0.5) Ma, (87.34±0.4) Ma, (88.5±0.5) Ma, and (87.1±0.5) Ma, respectively, all belonging to the late Yanshanian period. The Bainiuchang monzogranite is characterized by high silicon (SiO2=66.27%-73.77%) and high alkali (Na2O+K2O=6.17%-8.48%) contents, with high total rare earth elements (ΣREE=172.49×10-6-333.22×10-6, average 271.30×10-6), obvious fractionation of light and heavy rare earth elements (LREE/HREE=12.74-20.47, average 16.76), and weak negative Eu anomalies (0.44-0.78). It is relatively enriched in large ion lithophile elements (Rb, K) and high field strength elements (Th, U, Ce, Zr, Hf, Ta), belonging to peraluminous high-K calc-alkaline S-type granite. The zircon εHf(t) values of the Bainiuchang monzogranite range from -21.5 to -4.3, with corresponding two-stage Hf model ages of 1259-1614 Ma, indicating that the magma was derived from the melting of Mesoproterozoic-Neoproterozoic ancient crustal materials. Comprehensive analysis suggests that the formation of the Bainiuchang F3 fault provided migration channels and space for deep magmatic activity in the study area. The upwelling of granitic magma transported ore-forming elements such as Sn, Cu, and Zn, and consolidated to form the deep concealed granite. The formation of the deep concealed monzogranite in Bainiuchang is closely related to the tectonic transition from syn-collision to post-collision orogeny in the late Yanshanian period.

Key words: zircon U-Pb dating, LA-ICP-MS, monzogranite, deep concealed granite body, Bainiuchang

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