西藏甲玛铜多金属矿电气石矿物学特征及其对热液流体演化的指示  

Mineralogical characteristics of tourmaline in the Jiama copper polymetallic deposit,Tibet:Insights into hydrothermal evolution

作　　者：唐攀 唐菊兴[2] 林彬[2] 李发桥 孙渺 祁婧 崔浩 王梦蝶 熊妍 傅渊慧 张忠坤 杨征坤 姚晓峰[6] 谢金玲 陶刚 杨欢欢[2] TANG Pan;TANG Juxing;LIN Bin;LI Faqiao;SUN Miao;QI Jing;CUI Hao;WANG Mengdie;XIONG Yan;FU Yuanhui;ZHANG Zhongkun;YANG Zhengkun;YAO Xiaofeng;XIE Jinling;TAO Gang;YANG Huanhuan(The Key Laboratory of the Ministry of Education on Solid Waste Treatment and Recycling,School of Environment and Resource,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;China University of Geosciences,Beijing 100083,China;Chengdu University of Technology,Chengdu 610059,Sichuan,China;Tibet Huatailong Ming Corp.Ltd.,Lhasa 850212,Tibet,China;Development and Research Centre,China Geological Survey,Beijing 100037,China;Tibet University,Lhasa 850000,Tibet,China)

机构地区：[1]西南科技大学环境与资源学院,固体废物处理与资源化教育部重点实验室,四川绵阳621010 [2]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [3]中国地质大学(北京),北京100083 [4]成都理工大学,四川成都610059 [5]西藏华泰龙矿业开发有限公司,西藏拉萨850212 [6]中国地质调查局发展研究中心,北京100037 [7]西藏大学,西藏拉萨850000

出　　处：《中国地质》2024年第4期1123-1138,共16页Geology in China

基　　金：国家重点研发计划项目(2022YFC2905004);四川省自然科学基金(23NSFSC4281);西南科技大学科研基金(22zx7127);国家自然基金科研项目(41902097、42072313、41902101);中国地质科学院矿产资源研究所基本科研业务费(KJ2102、KK2017);大宗紧缺战略性矿产重点调查区块优选(重要矿山深部预测及外围勘查区块优选)(DD20230362)联合资助。

摘　　要：【研究目的】角岩作为甲玛超大型斑岩铜多金属成矿系统的重要组成部分,既是成矿热液的岩性圈闭,也是重要的赋矿围岩,但角岩中的电气石成因不明,对于进一步理解成矿过程有一定制约。【研究方法】本文通过详细的钻孔编录、镜下鉴定和电子探针分析,研究电气石的成因,并探讨其对岩浆热液流体演化过程的启示。【研究结果】电气石在甲玛角岩中较为发育,依据其产状可分为4类:Tur-I,热液角砾岩胶结物中的电气石;Tur-Ⅱ,石英+电气石±黄铁矿脉;Tur-Ⅲ,电气石±黄铁矿±黄铜矿脉;Tur-Ⅳ,团斑状电气石±黄铁矿;其中前3类电气石较发育环带结构。不同产状电气石均具有较为宽泛的Al_(2)O_(3)、Fe/(Fe+Mg)和Na/(Na+Ca)比值,属于碱基亚类镁电气石和黑电气石,替代机制为^(X)□Al(NaMg)_(-1)、Fe^(2+)Mg_(-1)和Fe^(3+)Al_(-1)。【结论】不同产状电气石发育复杂的环带结构,且成分变化极大,表明其是岩浆热液流体和地层流体不同程度混合造成的,且岩浆热液流体与还原性的角岩地层发生的水岩反应可能在甲玛成矿过程中起了重要作用。甲玛不同产状电气石的结构和成分信息记录了岩浆热液演化过程的细节信息,为完善成矿过程提供了重要证据。This paper is the result of mineral exploration engineering.Objective Hornfels,as an important part of the Jima porphyry copper polymetallic system,is host rocks and a lithologic trap for ore−forming fluid.However,the origin of tourmaline in hornfels is unknown,which restricts the further understanding of the mineralization.Methods We carried out detailed drilling logging,petrographic observations and major element analyses of tourmaline with distinctive occurrences in hornfels from the Jiama deposit to elucidate the genesis of tourmaline and evolution of magmatic hydrothermal fluids.Results Four types of tourmalines in hornfels from the Jiama deposit have been identified in this study:1)Tur−I,tourmaline occurring as cement in hydrothermal breccias;2)Tur−II,quartz+tourmaline±pyrite vein;3)Tur−III,tourmaline±pyrite±chalcopyrite vein;4)porphyritic tourmaline±pyrite.Tourmaline with distinctive occurrences in hornfels,which belongs to alkali group and dravite−schorl solid solution series,has a wide range of Al_(2)O_(3),Fe/(Fe+Mg)and Na/(Na+Ca).^(X)□Al(NaMg)_(-1)、Fe^(2+)Mg_(-1)and Fe^(3+)Al_(-1) exchange dominates the substitutions of Tur−I−IV.Conclusions Tourmaline in hornfels with complicated zoning texture has a very variable compositions,indicating that the tourmaline is caused by different degrees of mixing of magmatic hydrothermal fluid and formation fluid,and the water−rock interaction between magmatic hydrothermal fluid and reduced hornfels may play an important role on the mineralization.The various textures and compositions of tourmaline with distinctive occurrences in hornfels from Jiama record some detailed information related to evolution of magmatic hydrothermal fluid,and can provides evidence for understanding the mineralization.

关 键 词：电气石 岩浆热液演化 斑岩成矿系统 甲玛铜多金属矿 冈底斯成矿带 矿产勘查工程 西藏 

分 类 号：P618.2[天文地球—矿床学]