赣南加里东期重稀土矿赋矿母岩岩石成因及地质意义  

Petrogenesis and Geological Significance of the Caledonian Heavy Rare Earth Ore Parent Rockin Southern Jiangxi Province

作　　者：张德富[1,2] 王先广 何涛 曹明轩 吕婷婷 龚良信 徐进 ZHANG Defu;WANG Xianguang;HE Tao;CAO Mingxuan;LYUTingting;GONG Liangxin;XU Jin(School of Earth Science,East China University of Technology,Nanchang,Jiangxi330013,China;Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources,Jiangxi College of Applied Technology,Ganzhou,Jiangxi341000,China;Jiangxi Mineral Resources Guarantee Service Center,Nanchang,Jiangxi330013,China;Jiangxi Nonferrous Geology and Mineral Exploration and Development Institute,Nanchang,Jiangxi330013,China;Hefei University of Technology,School of Resources and Environmental Engineering,Hefei,Anhui230000,China;Ganzhou General Inspection and Testing Institute,Ganzhou,Jiangxi341000,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]江西应用技术职业学院自然资源部离子型稀土资源与环境重点实验室,江西赣州341000 [3]江西省矿产资源保障服务中心,江西南昌330013 [4]江西省地质调查勘查院基础地质调查所,江西南昌330013 [5]合肥工业大学资源与环境工程学院,安徽合肥230000 [6]赣州市综合检验检测院,江西赣州341000

出　　处：《现代地质》2024年第4期959-976,共18页Geoscience

基　　金：江西省安远县石头坪离子型中重稀土成矿作用及绿色采选技术试验项目(20220014);江西省自然资源厅科技创新项目(ZRKJ20232411,ZRKJ20232526);自然资源部离子型稀土资源与环境重点实验室开放基金课题(2022IRERE101,2022IRERE103)。

摘　　要：前人对燕山期重稀土赋矿母岩研究较多,加里东期赋矿母岩报道较少。本文对加里东期赣南孙屋岩体黑云母二长花岗岩开展岩石地球化学、锆石U-Pb年代学、Lu-Hf同位素及Sr-Nd同位素研究,并对其稀土含矿性进行探讨。孙屋岩体SiO_(2)含量为69.70%~73.00%,K2O/Na2O值为1.38~2.20,A/CNK值1.20~1.67,属于高硅高钾钙碱性-钾玄S型花岗岩。轻稀土相对富集((La/Yb)N=6.78~10.38),中等负铕异常(δEu=0.43~0.63)。两件花岗岩锆石206Pb/238U加权平均年龄为(451±3.8)Ma和(461±5.6)Ma,属中奥陶世。锆石Hf同位素地壳模式年龄(TDMC)为1918~1496 Ma,全岩Nd同位素二阶段模式年龄(TDM2)为1.79~1.76 Ga,显示岩浆源区主要为中元古代下地壳麻粒岩相源岩,岩体为华南加里东早期陆内造山环境花岗岩。孙屋岩体(含)稀土矿物经过风化可形成离子吸附型重稀土矿床,加里东期花岗岩在今后的重稀土矿产勘查工作中应给予足够重视。本文的研究成果可为加里东期花岗岩风化壳离子吸附型稀土矿找矿提供参考。Many studies have been conducted to investigate the Yanshanian heavy rare earth ore-bearing parent rocks,however only a few reports concern the Caledonian ore-bearing parent rocks.In this study,we analyzed the geochemistry,zircon U-Pb geochronology,Lu-Hf and Sr-Nd isotopes of the biotite monzonitic granites in the Caledonian Sunwu pluton in Southern Jiangxi Province.The rock samples show a SiO_(2) content of 69.7%-73.0%,a K2O/Na2O ratio of 1.38-2.20,and an A/CNK ratio of 1.20-1.67,belonging to the high-silicon and high-potassium-calcium alkaline-potassium basaltic S-type granite.The rock samples are relatively enriched in light rare earths((La/Yb)N=6.78-10.38)and show moderate negative europium anomalies(δEu=0.43-0.63).The weighted average ages of zircon 206Pb/238U in the two granites are(451±3.8)Ma and(461±5.6)Ma,respectively,belonging to the Middle Ordovician Epoch.The crustal model age(TDMC)for Hf iso-tope of zircon is 1918-1496 Ma,and for the whole rock is 1.79-1.76 Ga.The magma source area is mainly composed of Mesoproterozoic lower crust granulite facies source rocks,and the rock mass is intraplate granite formed during the Early Caledonian intracontinental orogeny in South China.The weathering of rare earth ele-ment-bearing minerals in the Sunwu pluton can form ion-adsorption heavy rare earth deposits.The Caledonian granite should be given sufficient attention in future exploration work for heavy rare earth elements.The re-search results provide a reference for the exploration of ion-adsorbed rare earth deposits in the weathering crust of Caledonian granite.

关 键 词：二长花岗岩 U-Pb定年 LU-HF同位素 SR-ND同位素 孙屋岩体 离子吸附型稀土矿 

分 类 号：P581[天文地球—岩石学] P597[天文地球—地质学] P618.7