内蒙古乌努格吐山斑岩铜钼矿床成矿流体演化——基于短波红外光谱、云母成分和石英流体包裹体研究  

Ore-forming fluid evolution of the Wunugetushan porphyry Cu-Mo deposit,Inner Mongolia:Evidence from the short-wave infrared spectrum,mica composition and fluid inclusion of quartz

作　　者：楚翔凯 申萍[1,2] 李昌昊 林强[3] CHU XiangKai;SHEN Ping;LI ChangHao;LIN Qiang(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;China Gold Inner Mongolia Mining Co.,Ltd.,Manzhouli 021400,China)

机构地区：[1]中国科学院地质与地球物理研究所,矿产资源研究院重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]中国黄金集团内蒙古矿业有限公司,满洲里021400

出　　处：《岩石学报》2023年第11期3461-3478,共18页Acta Petrologica Sinica

基　　金：中国科学院国际合作局国际伙伴计划(132A11KYSB20190070);国家自然科学基金重大研究计划重点支持项目(91962213);上海合作组织国际科技合作计划项目(2020E01043);国家重点研发计划政府间国际科技创新合作专项(2021YFE0190600);国家自然科学青年基金项目(42002092)联合资助。

摘　　要：内蒙古乌努格吐山斑岩铜钼矿床是中国东北地区最大的斑岩矿床之一,发育显著的石英-绢云母化蚀变,对早期的钾硅化蚀变有强烈的叠加改造,模糊了各蚀变的分带特征和不同矿化之间的关系,复杂的流体改造阻碍了精细热液演化过程的重建。本文以白云母为研究对象,在细致的显微镜、扫描电镜分析确定云母的形态特征以及矿物共生组合等基础上,利用电子探针(EPMA)、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)以及短波红外光谱(SWIR)分析手段,详细揭示不同阶段、不同产状白云母的成分差异,探讨了其对矿床热液演化以及成矿机制的指示意义。结果显示,乌山斑岩矿床的白云母由白云母端员及少量钠云母、绿鳞石、伊利石端员组成。与辉钼矿有关的云母更富集Al、K、Sr、Ba,且Al-OH特征波长在2197~2203nm之间。与黄铜矿有关的云母具有更高的Si、Ti、Fe、Mn、Mg、Cu、Zn、Sn、W等元素含量,Al-OH特征波长在2200~2206nm之间。氧化环境下形成的云母更富集Sc、V、W。乌山斑岩矿床的白云母在2200nm处吸收峰位置的波长偏移与距离成矿中心的远近及矿化类型有关,特征波长<2203nm则指示钼矿化,并且靠近成矿中心,因此可以利用SWIR特征圈定热液活动区域,确定矿化类型,指导找矿勘查工作。石英流体包裹体测温证据、白云母成分等信息,暗示铜沉淀阶段存在其他流体补充注入。综上所述,白云母作为常见的蚀变、热液矿物,对研究成矿流体演化及矿床勘查评价具有重要的科学意义。The Wunugetushan porphyry Cu-Mo deposit in Inner Mongolia is one of the largest porphyry deposits in Northeast China.This deposit is characterized by strong sericite alteration which overprinted the early potassic alteration.It obfuscated the zoning characteristics of alteration and its correlation with different mineralization.In addition,the complex fluid activity makes it difficult to constraint the hydrothermal evolution.Our study takes mica as the fingerprint mineral to constraint the hydrothermal evolution.In order to reveal the mica significance for the hydrothermal evolution and mineralization mechanism of the deposit,electron probe(EPMA),laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)and short-wave infrared spectrum(SWIR)were used to constraint the composition of several different micas which developed at different stages or different mineral association mica.The results show that the mica of Wunugetushan porphyry deposit primarily is phengite.The mica associated with molybdenite had high Al,K,Sr and Ba content,and the Al-OH wavelength ranged from 2197nm to 2203nm.Mica associated with chalcopyrite had high Si,Ti,Fe,Mn,Mg,Cu,Zn,Sn,and W,and the Al-OH wavelength ranged from 2200nm to 2206nm.Moreover,in oxidized hydrothermal environment,mica had high Sc,V and W contents.The Al-OH wavelength of mica in Wunugetushan porphyry deposit is related to the distance from the mineralization center,while the wavelength 2203nm indicates the molybdenum mineralization and closer the mineralization center.Hence,SWIR can be used to prospect the hydrothermal activity center,determine the mineralization type and the prospect area.The evidence of fluid inclusions from quartz,and mica composition suggest that exotic hydrothermal fluid injected before copper precipitation stage.Therefore,mica,as a common alteration and hydrothermal mineral,is of great scientific significance to the research of hydrothermal fluid evolution and exploration.

关 键 词：乌努格吐山 斑岩铜钼矿床 云母成分 流体演化 矿化过程 

分 类 号：P578.959[天文地球—矿物学] P618.41[天文地球—地质学] P618.65