滇东南燕山晚期老君山花岗岩的地球化学特征与年龄谱系  

Geochemistry and age spectrum of Late Yanshanian granites from Laojunshan Area, Southeastern Yunnan Province, China

作　　者：蓝江波[1] 刘玉平[1] 叶霖[1] 张乾[1] 王大鹏[1] 苏航 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550081 [2]华联矿产勘探有限责任公司,云南曲靖655000

出　　处：《矿物学报》2016年第4期441-454,共14页Acta Mineralogica Sinica

基　　金：云南华联锌铟股份有限公司委托项目(KY20120910);矿床地球化学国家重点实验室"十二五"项目群(SKLODG-ZY125-04)

摘　　要：对滇东南燕山晚期老君山花岗岩开展了全岩主-微量元素、Sr-Nd-Pb同位素、锆石LA-MC-ICPMS U-Pb定年研究。结果表明该岩体岩石化学成分总体上属于高K钙碱性系列,其铝饱和指数ACNK多大于1.1;标准矿物计算显示大多数样品含有标准刚玉分子（1%～5%）;认为老君山花岗岩为过铝-强过铝S型花岗岩,是古老地壳物质部分熔融的产物,其源岩可能为滇东南地区中-古元古代结晶基底中的一套变质泥岩为主,含少量变质硬砂岩的泥砂质副变质岩。根据锆石U-Pb定年结果,可将该复式岩体形成年龄分为80～88 Ma、90～98 Ma、100～118 Ma等三幕。老君山花岗岩成岩与锡矿化时代的一致性,表明都龙锡矿化与燕山期岩浆热液活动关系密切,老君山花岗岩是都龙锡锌多金属矿床成矿物质的主要源区。滇东南个旧、白牛厂和都龙等三个超大型矿床的成矿和成岩时代的耦合关系可能暗示其经历了相似的动力学背景,均与燕山期岩浆事件和华南岩石圈伸展密切相关。In this paper, Laojunshan granites were collected systematically. Zircon U-Pb dating, whole rock major and trace elements, and Sr-Nd-Pb isotope analysis were carried out to understand their petrogenesis and the relationship between respective mineralizations. Results show that Laojunshan granite belongs to high-K calc-alkaline series. The ACNK is higher than 1, and most of them higher than 1.1. CIPW results show that most of the samples contain standard corundum molecules（1%-5%）, indicating that Laojunshan granite are peraluminous S-type granites. Whole rock major-trace elements and Sr-Nd-Pb isotopic characteristics indicate that Laojunshan granite is highly fractionated S-type granites. Geochemical and isotopic data suggest that these highly fractionated S-type granites originated from partial melting of the protolith, which has analogous components in mixture of metamorphosed pelitic and psammitic rocks from the Meso-Paleoproterozoic continental crust. LA-MC-ICPMS U-Pb dating results show that Laojunshan granite can be divided into three episodes, i.e. 80-88 Ma, 90-98 Ma, and 100-118 Ma. Laojunshan granite is consistent with the age of tin mineralization. The consistency implies that Dulong tin mineralization has close relation with granitic magmatic hydrothermal. Laojunshan granite may be likely an important source of minerals reservoir for Dulong tin zinc polymetallic deposits.The coupling between mineralization and emplacement in Gejiu, Bainiuchang, and Dulong, Southeast Yunnan Province imply that thoses deposits formed in similar dynamic background, and are closely related to the same magmatic events and lithospheric extension of South China.

关 键 词：花岗岩 地球化学 锆石U-PB年代学 都龙锡锌多金属矿床 滇东南 老君山 

分 类 号：P579[天文地球—矿物学] P618.4[天文地球—地质学]