摘要
本文报道水口山矿田花岗闪长岩和英安玢岩的矿物学、同位素年代学、岩石地球化学和Sr-Nd同位素资料。电子探针分析结果显示,花岗闪长岩中黑云母为富镁黑云母,斜长石主要为中长石,而英安玢岩中斜长石成分为奥-钠长石。锆石U-Pb定年结果显示,英安玢岩形成于148.8±0.5 Ma,较花岗闪长岩晚近10 Ma。石榴子石原位U-Pb定年结果显示,康家湾矿区深部矽卡岩形成于159.1±1.9 Ma,与花岗闪长岩形成时代一致。地球化学特征显示,水口山岩浆岩均具有富Al、低Si、高K/Na值特征,为亚碱性、高钾钙碱性-钾玄岩系列岩石。各类岩石富集Rb、Th、U,亏损Ba、Nb、Sr、Ti等。Sr-Nd同位素特征显示,花岗闪长岩和英安玢岩的(^(87)Sr/86^(Sr))i值分别为0.70661~0.70801和0.71116~0.711156,ε_(Nd)(t)值分别为-7.4~-2.4和-8.63~-7.1,T_(DM2)值分别为1.55~1.15 Ga和1.64~1.53 Ga,揭示英安玢岩和花岗闪长岩来自中元古代中下地壳变质杂砂岩-玄武质英云闪长岩的部分熔融,为不同期次不同深度岩浆作用的产物。成岩成矿时代、地球化学特征和矿物学特征综合表明,花岗闪长岩与水口山多金属成矿作用关系密切,且整个水口山矿田形成于燕山期早期晚阶段古太平洋板块俯冲背景下的陆内伸展环境。
We reported systematic mineralogical,geochronological,geochemical and Sr-Nd isotopic data of granodiorite and dacite porphyry in Shuikoushan ore field.The EMPA analysis result shows that the biotite in granodiorite is magnesium-rich biotite and the plagioclase is main andesine,while the plagioclase in dacite porphyry is main oligoclase-albite.Zircon U-Pb age shows that the dacite porphyry was formed at 148.8±0.5 Ma,which is about 10 Ma later than the granodiorite.However,the in situ U-Pb age of garnet shows that the deep skarn of Kangjiawan deposit was formed at 159.1±1.9 Ma,which is much closer to the formation age of granodioritie.Geochemical characteristics shows that the magmatic rocks in Shuikoushan are enriched in Al,low in Si and high in K/Na ratio,and have the affinity of subalkaline and high K calc-alkaline to shoshonite series.They are enriched in Rb,Th,U and depleted in Ba,Nb,Sr,Ti,etc.Sr-Nd isotopic characteristics show that the(^(87)Sr/86^(Sr))i ratios range from 0.70661 to 0.70801 and 0.71116 to 0.711156 for granodiorite and dacite porphyry,respectively.The calculated ε_(Nd)(t)values range from-7.4~-2.4 and-7.1 to-8.63 for granodiorite and dacite porphyry,respectively.The T_(DM2) values of granodiorite range from 1.53 Ga to 1.15 Ga and of dacite porphyry are from 1.64 Ga to 1.53 Ga.It suggests that the granodiorite and dacite porphyry were derived from partial melting of Mesoproterozoic metamorphic basaltic tonalite diorite.They are formed at the different stages of magmatism and derived from distinct source regions.The evidence of formation ages,geochemical characteristics and mineralogical characteristics suggest the affinity between granodiorite and polymetallic mineralization.The Shuikoushan ore field was formed in the intracontinental extensional setting under the subduction background of paleo-Pacific plate at the late stage of early Yanshanian.
作者
秦锦华
王登红
王成辉
赵如意
刘善宝
QIN Jinhua;WANG Denghong;WANG Chenghui;ZHAO Ruyi;LIU Shanbao(MNR Key Laboratory of Metallogeny and Mineral Assessment/Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;State Key Laboratory of Nuclear Resources and Evironment/East China University of Technology,Nanchang 330013,Jiangxi,China)
出处
《地质通报》
CAS
CSCD
北大核心
2023年第7期1179-1202,共24页
Geological Bulletin of China
基金
中国地质调查局项目《中国矿产地质志》(编号:DD20190379)。
关键词
水口山
年代学
花岗闪长岩
伸展
成矿作用
地质调查工程
Shuikoushan
geochronology
granodiorite
extension
mineralization
geological survey engineering
