西藏多龙矿集区波龙、多不杂斑岩铜金矿床岩体锆石Ce^4+/Ce^3+比值及氧逸度特征  

CHARACTERISTICS OF Ce^4+/Ce^3+RATIO AND OXYGEN FUGACITY OF ZIRCON IN PORPHYRY FROM BOLONG AND DUOBUZA PORPHYRY Cu-Au DEPOSITS IN DUOLONG ORE DISTRICT,TIBET

作　　者：李云强 费光春[1] 温春齐[1] 曾鑫 赵德坤[2] Li Yunqiang;Fei Guangchun;Wen Chunqi;Zeng Xin;Zhao Dekun(College of Earth Sciences,Chengdu University of Technology,Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Natural Resources,Chengdu,Sichuan 610059 China;Sichuan Institute of Metallurgical Geology,^Exploration,Chengdu,Sichuan 610051,China)

机构地区：[1]成都理工大学地球科学学院,自然资源部构造成矿成藏重点实验室,四川成都610059 [2]四川省冶金地质勘查院,四川成都610051

出　　处：《矿物岩石》2020年第2期59-70,共12页Mineralogy and Petrology

基　　金：国家自然科学基金(41702074);自然资源部公益性行业科研专项(201011013);成都理工大学中青年教学骨干教师资助项目(JXGG201701);四川省科技厅应用基础研究项目(2019YJ0285);国家留学基金委资助(201908510007)。

摘　　要：波龙、多不杂斑岩铜金矿床是青藏高原中部发现的两个大型斑岩铜金矿床。对波龙、多不杂斑岩铜金矿床含矿花岗闪长斑岩和不含矿花岗闪长斑岩的锆石Ce^4+/Ce^3+比值以及氧逸度等特征进行研究,并且通过计算得到了3个含矿花岗闪长斑岩的锆石Ce^4+/Ce^3+比值分别为536.03,492.18,454.02;1个不含矿的花岗闪长斑岩的锆石Ce^4+/Ce^3+比值为0.67。说明波龙、多不杂斑岩矿床中与成矿相关的岩体具有相对更高的氧化状态。对比西藏冈底斯成矿带中的斑岩矿床、云南中甸岛弧成矿带中的烂泥塘斑岩铜矿床、金沙江-红河成矿带中的马厂箐、铜厂铜钼矿以及玉龙成矿带铜钼矿床岩体的锆石Ce^4+/Ce^3+比值,发现含矿岩体锆石Ce^4+/Ce^3+比值一般>250。结合波龙、多不杂矿床的锆石Ce^4+/Ce^3+的计算结果发现Ce^4+/Ce^3+基本>300,因此将锆石Ce^4+/Ce^3+>300作为波龙、多不杂矿床斑岩成矿的一个地球化学标志。此外,通过(Ce^/Ce^*)D锆石氧逸度计和(XCe^4+melt/XCe^3+melt)锆石氧逸度计计算得到的波龙、多不杂矿床含矿花岗闪长斑岩体的氧逸度(log(fO2))分别位于MH(磁铁矿-赤铁矿)缓冲带和FMQ(铁橄榄石-磁铁矿-石英)缓冲带之上,平均值为ΔMH+3.24和ΔFMQ+1.78,前人研究发现多不杂含矿石英斑岩的氧化状态较高,平均ΔNNO+2.4,含矿斑岩体的形成具有较高的氧逸度条件,说明高氧逸度更有利于多龙矿集区斑岩型铜矿成矿。Study of zircon Ce^4+/Ce^3+ratios and oxygen fugacity of ore-bearing granite diorite porphyry and barren granite diorite porphyry of Bolong and Duobuza porphyry Cu-Au deposits in the central Tibetan Plateau shows that the zircon Ce^4+/Ce^3+ratios of three ore-bearing granodiorite porphyry samples are 536.03,482.18 and 454.02,while the zircon Ce^4+/Ce^3+ratios of no ore-bearing granodiorite porphyry sample is 0.64.The oxidation state of ore-bearing intrusions is relatively higher than that of no ore-bearing intrusions.Comparison of Ce^4+/Ce^3+ratios of ore-bearing intrusions and no ore-bearing intrusions in the Gangdese metallogenic belt with those of Lannitang porohyry copper deposit in Zhongdian island arc in Yunnan,of Machangqing and Tongchang porphyry Cu-Mo deposit in Jinshajiang-Red River metallogenic belt,of Cu-Mo deposit in Yulong metallogenic belt indicates that the Ce^4+/Ce^3+ratios of ore-bearing intrusions are usually greater than 250,while the no ore-bearing intrusions usually less than 250.It is found that the Ce^4+/Ce^3+ratio of the Bolong and Duobuza deposit are basically over 300,which can be used as the geochemical indicators for Bolong and Duobuza porphyry Cu-Au deposit.Calculation value of oxygen fugacity of ore-bearing granite diorite porphyry by(Ce^/Ce^*)D oxy-barometers is basically located on the MH buffer with average ofΔMH+3.24,and the oxygen fugacity by(XCe^4+melt/XCe^3+melt)oxy-barometers is all located on the FMQ buffer with average ofΔFMQ+1.78.Previous research revealed that the mineralized Duobuza quartz diorite porphyry has a high oxidation state(averageΔNNO+2.4),and therefore,high oxygen fugidity is a favorable condition for the porphyry copper mineralization in Duolong.

关 键 词：斑岩铜金矿床 锆石Ce^4+/Ce^3+比值 氧逸度 班公湖-怒江成矿带 多龙矿集区 

分 类 号：P595[天文地球—地球化学] P612[天文地球—地质学]