云南个旧阳山地区淡色花岗岩成因与成矿效应:岩石地球化学和独居石U-Pb年代学方面的制约  

Petrogenesis and Mineralization of Leucogranite In Yangshan Area,Gejiu City,Yunnan Province:Constraints On Petrogeochemistry and Monazite U-Pb Dating

作　　者：肖述刚 徐恒 常国虎 余莉 王宗元 张忠明 张俊学 汤俊 卢楠迪 杨文坚 XIAO Sugang;XU Heng;CHANG Guohu;YU Li;WANG Zongyuan;ZHANG Zhongming;ZHANG Junxue;TANG Jun;LU Nandi;YANG Wenjian(No.308 Geological Party,Yunnan Nonferrous Metals Geological Bureau,Kunming,Yunnan 650200,China;No.306 Geological Party,Yunnan Nonferrous Metals Geological Bureau,Kunming,Yunnan 650217,China;Yunnan Golden Geology Erploration Technology Service Company,Kunming,Yunnan 650200,China)

机构地区：[1]云南省有色地质局三0八队,云南昆明650200 [2]云南省有色地质局三0六队,云南昆明650217 [3]云南金色地质勘查技术服务有限公司,云南昆明650200

出　　处：《矿物岩石》2024年第4期41-57,共17页Mineralogy and Petrology

基　　金：云南省有色地质局三0八队个旧西区新发现阳山锂铷矿成岩成矿作用研究(编号:2023001);云南省技术创新人才培养对象项目(编号:202105AD160003);第二次青藏高原综合科学考察研究(编号:2019QZKK0802);云南省蒋少涌专家工作站(编号:202405AF140108)

摘　　要：为揭示新发现的云南个旧阳山淡色花岗岩成因及其Li、Rb矿化控制因素,对其进行了岩石学、岩石地球化学和独居石的U-Pb年代学研究。研究结果显示:阳山淡色花岗岩由细粒(FGG)和中-细粒花岗岩(MFGG)组成,二者岩相学特征类似,空间上无明显分带关系,呈渐变过渡关系,具典型花岗结构。FGG和MFGG蕴含高硅(w(SiO_(2))=75.8%~78.8%)、高钾(K_(2)O/Na_(2)O=0.67~1.76)、高铝(w(Al_(2)O_(3))=11.48%~13.09%)、低镁值(Mg~(#)=13.0~32.1)和强过铝质(A/CNK=1.21~1.66)特征,属强过铝质钙碱性-高钾钙碱性系列岩石;样品具高分异指数(DI=88.98~94.92),强负Eu异常(δEu=0.003~0.011),富集Rb(1220×10^(-6)~1780×10^(-6))、Ta(31.0×10^(-6)~70.5×10^(-6))和Pb(48.4×10^(-6)~134.0×10^(-6)),亏损Ba(3.16×10^(-6)~10.40×10^(-6))、Sr(2.58×10^(-6)~7.92×10^(-6))、Eu(0.003×10^(-6)~0.021×10^(-6))、P(0.379×10^(-6)~18.914×10^(-6))和Ti(12.685×10^(-6)~31.812×10^(-6)),Nb/Ta(0.98~2.07)和Zr/Hf(8.12~11.70)远低于地幔物质和上地壳物质,以及明显的REE四分组效应(TE1,3=0.98~1.33)特征,指示岩浆经历过高分异演化作用;样品富含白云母,强过铝质和P_(2)O_(5)与SiO_(2),Y、Th与Rb的协变关系,与S-型花岗岩特征一致。FGG和MFGG独居石的U-Pb年龄分别为88.3±0.22 Ma和85.7±0.18 Ma,表明其形成于晚白垩世。结合已有研究,认为阳山淡色花岗岩属高分异的过铝质S-型花岗岩,起源于晚-中元古代富黏土泥质岩相地壳物质的部分熔融,形成于燕山晚期碰撞造山晚期的伸展背景下。该岩体经历的高程度分离结晶作用和岩浆期后熔-流体相互作用是稀有金属Li和Rb富集成藏的关键控制因素。Petrology,whole-rock geochemistry,and monazite U-Pb geochronology were applied to inves-tigate the factors influencing the petrogenesis and mineralization of Li and Rb in the newly discovered leu-cogranite in the Yangshan area,Gejiu city,Yunnan Province.The findings indicate that the leucogranite comprises fine-grained granite(FGG)and medium-to fine-grained granite(MFGG),both exhibiting simi-lar petrographic features.They both display typical granite textures,with a gradual spatial transition,but showing no distinct zoning or sharp contacts.Both FGG and MFGG show high silicon(w(SiO_(2))=75.8%-78.8%),potassium(K_(2)O/Na_(2)O=0.67-1.76),and aluminum contents(w(Al_(2)O_(3))=11.48%-13.09%),while displaying low magnesium(Mg^(#)=13.0-32.1)and strong peraluminous char-acteristics(A/CNK=1.21-1.66).Thus,the Yangshan leucogranite is classified as a member of the strong peraluminous calcium-alkaline to high potassium calcium-alkaline rock series.The samples demon-strate a high differentiation index(DI=88.98-94.92)and strong negative Eu anomalies(Eu=0.0030.011).They are enriched in Rb(1220×10^(-6)-1780×10^(-6)),Ta(31.0×10^(-6)-70.5×10^(-6)),and Pb((48.4×10^(-6)—134.0×10^(-6))whiledepleted in Ba(3.16×10^(-6)-10.40×10^(-6)),Sr(2.58×10^(-6)7.92×10^(-6)),Eu(0.003×10^(-6)-0.021×10^(-6)),P(0.379×10^(-6)-18.914×10^(-6)),and Ti(12.685×10^(-6)-31.812×10^(-6)).The samples also exhibit significantly lower Nb/Ta(0.98-2.07)and Zr/Hf(8.1211.70)ratios in relative to typical mantle and upper crust,as well as a notable REE tetrad effect(TE1,3=0.98-1.33),indicating a high magmatic differentiation degree.Furthermore,evidenced by abundant muscovite and strong peraluminosity,the samples display covariant relationships between P_(2)O_(5)and SiO_(2),Y,Th,and Rb,which align with characteristics of S-type granite.Monazite U-Pb ages of FGG and MFGG are 88.3±0.22 Ma and 85.7±0.18 Ma,respectively,intruded in Late Cretaceous.Based on previous research,the Yangshan leucogranite is interpreted as a highly differentiated,peraluminous S-

关 键 词：独居石U-Pb定年 岩石成因 成矿效应 阳山淡色花岗岩 云南个旧 

分 类 号：P542[天文地球—构造地质学] P595[天文地球—地质学] P597