河南嵩县庙岭金矿区花岗斑岩锆石U-Pb年龄、岩石地球化学和Sr-Nd-Pb同位素特征  

Zircon U-Pb age, geochemistry and Sr-Nd-Pb isotopic compositions of the granite porphyry in the Miaoling gold deposit of Songxian County,Henan Province

作　　者：李正远[1] 叶会寿[2] 曹晶[1] 张兴康[1] 翟雷[3] 

机构地区：[1]中国地质大学,北京100083 [2]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037 [3]河南省地质矿产勘查开发局第一地质矿产调查院,河南洛阳471023

出　　处：《岩石矿物学杂志》2014年第3期424-440,共17页Acta Petrologica et Mineralogica

基　　金：国土资源部成矿作用与资源评价重点实验室研究项目(ZS1308);中国地质调查局地质调查项目(12120114035401;1212011220869);国家自然科学基金项目(41272104)

摘　　要：河南嵩县庙岭金矿区地处华北陆块南缘熊耳山-外方山地区,LA-ICP-MS锆石U-Pb定年结果表明,庙岭金矿区花岗斑岩的成岩年龄为157 Ma左右。岩石地球化学数据显示岩石具有高硅,富钾、铝而贫钠,低铁、镁、钙的特征,SiO2含量为75.06%~77.66%,全碱含量(Na2O+K2O)为7.05%~7.39%;稀土元素总量较低,ΣREE=25.74×10-6~32.63×10-6,轻重稀土元素分馏明显,LREE/HREE=6.74~9.53,Eu具有中等的负异常;微量元素富集Rb、K、Pb等大离子亲石元素和Th、U,亏损Nb、Ta、Ti等高场强元素和Ba、Sr。Pb同位素分析结果显示庙岭金矿区花岗斑岩的Pb主要来自于下地壳;全岩的(87Sr/86Sr)i=0.706 207~0.711 774,εNd(t)值变化于-19.0^-17.8之间,tDM2=2.39~2.49 Ga。岩石地球化学和Sr-Nd-Pb同位素组成特征显示庙岭金矿区花岗斑岩的源区物质主要来自于古老下地壳,可能为太古宙太华群。The Miaoling gold deposit is located in the Xiong＇ ershan-Waifangshan area on the southern margin of the North China Craton.Zircon U-Pb LA-ICP-MS dating of the granite porphyry in the Miaoling gold deposit yielded an age of 157 Ma.Chemically,the granite porphyry is peralumious and characterized by richness of silicon and alkaline,with SiO2 equal to 75.06% ～77.66% and Na2O＋ K2O equal to 7.05% ～7.39%,and deficiency of iron,magnesium and calcium.Its REE values are relatively low,being 25.74 × 10 6～32.63 × 10-6,and display a significant fractionation between LREES and HREES （LREE/HREE =6.74～ 9.53）,with moderate negative anomalies of Eu （δEu =0.51～0.71）.The trace elements are characterized by enrichment of large ion lithophile elements （Rb,K,Pb,and Th,U）,and depletion of high-field strength elements （Nb,Ta,Ti and Ba,Sr）.The whole rock Sr-Nd compositions of the granite porphyry have the data （87 Sr/86 Sr）i =0.706 207～ 0.711 774 and εNd（t） =-19.0～-17.8,with Nd model ages in the range of 2.39～ 2.49 Ga.Plotting of lead isotopes of the granite porphyry on the 207pb/204pb diagrams and 208pb/204pb versus 206pb/204pb evolution curves show that the lead might have come from the crust source area.Geochemistry and Sr-Nd-Pb isotopic compositions suggest that the granite porphyry in the Miaoling gold deposit was derived from an ancient continental crust （probably the Archaean Taihua Group）.

关 键 词：LA-ICP-MS 锆石 U-PB年龄 岩石地球化学 SR-ND-PB 同位素 岩石成因 庙岭金矿区 

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