云南中甸红牛—红山斑岩—矽卡岩型铜矿床花岗斑岩岩石学特征及成因意义  

PETROLOGICAL CHARACTERISTICS AND GENETIC SIGNIFICANCE OF GRANITE PORPHYRY IN HONGNIU-HONGSHAN PORPHYRY-SKARN COPPER DEPOSIT,ZHONGDIAN AREA,YUNNAN PROVINCE

作　　者：杨东杰 彭惠娟[1] 王天瑞 李蕊 YANG Dongjie;PENG Huijuan;WANG Tianrui;LI Rui(College of Earth Science,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Panzhihua Pangang Group Mining Company,Panzhihua,Sichuan 617063,China;Sichuan Institute of Geological Engineering Investigation Group Co.Ltd,Chengdu,Sichuan 610072,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]攀钢集团矿业有限公司,四川攀枝花617063 [3]四川省地质工程勘察院集团有限公司,四川成都610072

出　　处：《矿物岩石》2023年第4期60-77,共18页Mineralogy and Petrology

基　　金：国家自然科学基金项目(批准号:4197020467,2021YJ0376)。

摘　　要：云南中甸红牛—红山矿床位于义敦岛弧南端,该区域主要发育印支期与燕山晚期两期成矿作用。本次研究对红牛—红山斑岩—矽卡岩型铜矿床与成矿有关的隐伏花岗斑岩锆石进行U-Pb年代学、元素地球化学以及同位素地球化学特征研究,结果表明:红牛—红山矿床与成矿相关的隐伏花岗斑岩属于I型花岗岩,其w(K_(2)O)为2.05%~7.32%;可见轻微负Eu异常,Eu/Eu^(*)变化范围为0.56~0.89;Mg^(#)值较低,为20.04~47.08,暗示加厚下地壳来源;(La/Yb)_(N)为28.65~103.24,呈现出强烈的轻重稀土分馏模式;Sr含量较高且变化范围较大,为131×10^(-6)~715×10^(-6),具埃达克岩的特征。花岗斑岩锆石Th/U比值为0.32~1.21,表明其为岩浆锆石;锆石平均协和年龄为76.7 Ma,与成矿年龄一致,表明其形成于晚白垩世;锆石重稀土元素显著富集,δEu=0.38~0.99,结晶温度为600.3~813.5℃,平均值为681.5℃,氧逸度平均值△FMQ=1.08,δ^(18)O平均值为6.8‰,暗示大量地壳物质的加入。锆石结晶环境暗示红牛—红山矿床锆石高氧逸度特征继承自印支期的俯冲改造物。The Hongniu-Hongshan deposits,located at the southern end of Yidun island arc in Zhongdian area,Yunnan Province,mainly developed two stages of mineralization,the Indosinian and the late Yanshanian.In this paper,the zircons from buried granite-porphyry related to the mineralization of the Hongniu-Hongshan porphyry skarn copper deposit are studied by means of U-Pb chronology,element geochemistry and isotope geochemistry.The results show that the Hongniu-Hongshan deposits and the buried granite porphyry related to the mineralization belong to type I granite,with relatively high K_(2)O content is relatively high,ranging from 2.05% to 7.32%.The rock shows slight negative Eu anomaly with Eu/Eu^(*)ranging from 0.56 to 0.89.The low Mg^(#)value(20.04-47.08)suggests the origin of the thickened lower crust.(La/Yb)_(N) value of 28.65-103.24 shows a strong light and heavy rare earth fractionation pattern and the high and widely changed content of Sr(131×10^(-6)-715×10^(-6))is characteristic of Adakite.The Th/U ratio of 0.32-1.21 for granite-porphyry zircon is an indication of magmatic zircon,and the mean concordant age of the zircon is 76.7 Ma(Late Cretaceous)which is consistent with the metallogenic age.Zircons in granite-porphyry are significantly enriched in heavy rare earth elements and the δEu is 0.38-0.99 with crystallization temperature of 600.3-813.5℃(average 681.5℃).The average oxygen fugidity △FMQ=1.08(mean 6.8‰)suggests the addition of a large number of crustal materials.The zircon crystalline environment implies that the high oxygen fugacity of zircon in Hongniu-Hongshan deposit is resulted from the westward subduction in Indosinian period.

关 键 词：云南中甸 花岗斑岩 U-PB年代学 元素地球化学 锆石微量元素 锆石氧同位素 

分 类 号：P581[天文地球—岩石学] P588.12.1[天文地球—地质学]