矿床地质2023，Vol.42Issue(6)：1101-1120,20.DOI:10.16111/j.0258-7106.2023.06.002
湘东南东风岩体锆石U-Pb年代学、Hf同位素组成及稀土矿床特征
Zircon U-Pb chronology,Hf isotopes and REE deposit characteristics of Dongfeng granitic pluton in southeastern Hunan Province
摘要
Abstract
s This paper presents new zircon LA-ICP-MS U-Pb ages,Lu-Hf isotope and geochemical data of the Dongfeng granitic pluton in southeastern part of Hunan Province,aiming to constrain its petrogenesis and tectonic implica-tion,and to explore the metallogenic mechanism of the Dongfeng ion adsorption type heavy rare-earth deposit.The LA-ICP-MS zircon U-Pb analysis of two biotite monzogranite yielded 206Pb/238U ages of(433.5±2.6)Ma and(432.0±2.5)Ma,respectively,suggesting that the Dongfeng granitic pluton formed in Late Caledonian.The gran-ites contain high K2O and belong to calc-alkali,strongly peraluminous(A/CNK=1.12～1.43),and geochemically classified as S-type granite.The primitive mantle-normalized trace element spider diagram shows that the Dong-feng monzogranite is relatively depleted in Ba,Nb,Sr,P,Ti and relatively enriched in Rb,(Th+U),Nd,(Zr+Hf)as well as zircon εHf(t)(-5.12 to-7.45)and 176Hf/177Hf(0.282 300 to 0.282 374)values indicating that this pluton is mostly product of crust melting.Tectonic setting discrimination diagrams show characteristics of monzogranite produced in post-collisional extensional environment.Hf isotopic and geochemical analyses indicate that the Dongfeng monzogranite belongs to S-type granite,derived from the partial melting of old crustal materials,when asthenosphere mantle upwelling,causing remelting of crustal materials under the geodynamical background of ex-tensional environment after intraplate convergence between Yangtze Plate and Cathaysia Plate.The Dongfeng de-posit is a newly discovered,large-sized ion adsorption type heavy rare-earth deposit,with an averaging grade of 0.050%～0.099%of REO,which formed from weathering of biotite monzogranite enriched in LREE,the high con-tent of Y in parent granite provides the major sources in the formation of the deposit.Topographic features and cli-matic characteristics in the Dongfeng area are the key conditions for eluviation and sorption inducing the forma-tion of ion adsorption type rare-earth deposit.关键词
东风花岗岩体/加里东期/锆石U-Pb定年和Hf同位素/离子吸附型稀土矿/矿床成因/湘东南Key words
Dongfeng granitic pluton/Caledonian/zircon U-Pb geochronology and Hf isotope/ion adsorp-tion type rare-earth deposit/ore genesis/southeastern Hunan Province分类
天文与地球科学引用本文复制引用
张锦煦,李超,陈剑锋,林碧海,廖凤初,孙骥,谭仕敏,何艳林,周超,朱继华,熊雄..湘东南东风岩体锆石U-Pb年代学、Hf同位素组成及稀土矿床特征[J].矿床地质,2023,42(6):1101-1120,20.基金项目
本文得到中国地质调查局二级项目(编号:DD20230055、12120115029301)、湖南省地质院科研项目(编号:HNGSTP202306)和湖南省自然资源厅科研项目(编号:2023-02)联合资助 （编号:DD20230055、12120115029301）
