滇中楚雄盆地六苴铜矿床煌斑岩地球化学、年代学及其地质意义  

Geochemistry,chronology and geological significance of lamprophyres from the Liuju sandstone copper deposit in the Chuxiong basin,central Yunnan

作　　者：吴鹏[1] 谭茂 韩润生[1] 江小均[1] 王蝶[1] 杨航 WU Peng;TAN Mao;HAN RunSheng;JIANG XiaoJun;WANG Die;YANG Hang(Faculy of land Resource Enyinering,Kurming Unisersily of Science and Technology,Kuwming 650093,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093

出　　处：《岩石学报》2020年第5期1409-1425,共17页Acta Petrologica Sinica

基　　金：国家自然科学重大研究计划项目(91855217);国家重点基础研究发展规划(“973”计划)项目(2015CB452600);国家自然科学基金项目(41102049);国家重点研发计划项目(SQ2018YFC06017102);云南省矿产资源预测评价工程实验室(2010);云南省地质过程与矿产资源创新团队(2012)联合资助.

摘　　要：云南六苴铜矿床是楚雄盆地砂岩型铜矿床的典型代表。矿区岩浆活动不明显,近年来通过深部钻孔和竖井工程,在矿床深部揭露出煌斑岩脉。通过岩相学、电子探针、ICP-MS、锆石U-Pb定年等分析,确定六苴铜矿床的煌斑岩属云煌岩,其成岩年龄为31~33Ma,于铜矿床的改造成矿期侵位。主量元素特征显示其属于钾质钙碱性煌斑岩;微量元素表现为大离子亲石元素Sr、Th和Rb等相对富集,高场强元素Nb、Ta和Ti等亏损;稀土元素表现出轻稀土强烈富集的特点。锆石176Hf/177Hf值为0.28230~0.28272,比较集中的Hf同位素组成εHf(t)=-4~2。综合分析认为,六苴铜矿床的煌斑岩主要源自流体交代的富集岩石圈地幔,岩浆在快速上升过程中进一步熔融混染了少部分先存的地壳残片,为喜马拉雅期印度-欧亚板块碰撞挤压背景下,从挤压转换为拉张环境的产物。该煌斑岩与富厚铜矿体二者在空间、时间、构造-热液、产出状态、成矿流体及物质来源等方面均具有紧密联系,对铜矿体的改造富集起到重要作用,可作为预测富厚铜矿体的指示标志。煌斑岩脉内含有方铅矿、闪锌矿等金属硫化物,暗示深部具铅锌成矿潜力。The Liuju copper deposit is a typical representative of sandstone deposit in the Chuxiong basin of Yunnan Province,Southwest China.The magmatic activity in the mining area i not obvious.In recent years,lamprophye veins have been exposed in the.deep part of the deposit through deep dilling and shaft engineering.Microscope,electron microprobe,ICP-MS and zitcon SHRIMP U-Pb dating analysis revealed that the lamprophyres from Liuju belong to minette and have similar forming ages(31~33Ma)to the reformation Cu metallogenic period in this deposit.Gochemically,the lamprophy es are potassic calc-alkaline series and are enriched in large ion lithophile elements(Sr,Th and Rb)and IREE and depleted in the high field strength elements(Nb,Ta and T).Furthermore,the 176 H/Hf ratios of lamprophyres zircons range from 0.28230 to 0.28272,with relatively concentrated Em(t)values varying fom-4 to 2.Based on the tectonie setting and comprehensive analysis reveals that the lamprophyres in Liuju Cu deposit were mainly derived from fluid metasomatism enriched lithospheric mantle.In the process of rapid rise,the magma further melted and mixed with a few remaining crustal fragments,due to collision between the Indian and Eurasian plate in Himalayan Period(during the.transitional stage fom compression to extension).In addition,considering lamprophyre and the rich copper deposit are closely related to each other in space,time,tectonic-hydrothermal solution,form,ore-forming fluid and material source,the lamprophyres might have contributed to the enrichment of Cu at Liuiju and can be used as potential indic ator for future exploration.Moreover,the lamprophyres.fom Liuju are rich in other sulfides(e.g,galena,sphalerite),implying potential Pb-Zn mineralization in the deep part of this deposit.

关 键 词：煌斑岩 地球化学 年代学 砂岩型铜矿床 楚雄盆地 

分 类 号：P588.13[天文地球—岩石学] P597.3[天文地球—地质学]