U-Pb dating of bastnäsite from the Vuoriyarvi massif:An example application for assessing the REE potential of carbonatite-related deposits  

作　　者：Evgeniy N.Kozlov Ekaterina N.Fomina Qiuli Li Jiao Li 

机构地区：[1]Geological Institute,Kola Science Centre of the Russian Academy of Sciences,Apatity 184209,Russia [2]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Geoscience Frontiers》2024年第5期444-453,共10页地学前缘（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.42241105);The research was funded by the Russian Science Foundation(Grant No.19-77-10039-P,study of the geology of bastnäsite ores and their economic potential);Preliminary investigations were supported by the Geological Institute KSC RAS,state order number FMEZ-2024-0004。

摘　　要：The Vuoriyarvi massif is a Devonian multistage alkaline-ultrabasic carbonatite complex within the Kola alkaline province.Dolomite carbonatites of the Vuoriyarvi massif contain abundant rare-earth mineralization mainly represented by ancylite-(Ce)and bastnäsite-(Ce).Ancylite was previously shown to have probably formed in the Devonian(ca.365 Ma)during an early postmagmatic overprint.Previous geological observations have revealed a much later crystallization of bastnäsite but have not been able to specify the exact age of the mineralization.The in situ U-Pb dating of bastnäsite allowed us to constrain its genesis.Bastnäsite for this study was extracted from two varieties of dolomite carbonatite breccias cemented by(1)quartz-bastnäsite and(2)strontianite aggregates(hereafter bastnäsite-rich and strontianite-rich carbonatites–BRC and SRC,respectively).The obtained age estimations(237.7±9.8 Ma and 239.9±4.1 Ma,respectively)indicate that both studied rocks were formed during a single event.The revealed age difference(~125 Ma)excludes the genetic link between the bastnäsite origin and regional alkaline magmatism,pointing out an additional source for the Vuoriyarvi bastnäsite-bearing rocks.Moreover,the obtained U-Pb ages provide strong evidence that a Triassic event is responsible for the occurrence of bastnäsite mineralization due to hydrothermal REE redistribution from the Devonian ancylite-rich carbonatites.Most of the REEs released during this process via dissolution of ancylite were precipitated in situ as bastnäsite,while strontium was transported and incorporated into strontianite.The Pb isotopic characteristics of bastnäsite(^(206)Pb/^(204)Pb=18.1±0.1,^(207)Pb/^(204)Pb=15.3±0.1,and^(207)Pb/^(206)Pb=0.84±0.01)are most probably inherited from the Devonian host rocks of the Vuoriyarvi massif involved in the Triassic overprint.Isotopic signatures of Pb,Sr,and Nd show that the depleted mantle and lower crust played the leading role in formation of the Vuoriyarvi alkaline complex.Taken together,the re

关 键 词：Bastnäsite REE CARBONATITES U-Pb dating Vuoriyarvi Kola alkaline province 

分 类 号：P624[天文地球—地质矿产勘探]