Geological Characteristics of Metallogenic Host Rock and Their Genetic Significance of Shitouping Heavy Rare Earth Deposit in Southern Jiangxi Province
Geological Characteristics of Metallogenic Host Rock and Their Genetic Significance of Shitouping Heavy Rare Earth Deposit in Southern Jiangxi Province
The Shitouping ion-adsorptive heavy rare earth deposit in southern Jiangxi province is a newly discov-ered large deposit.Due to the lack of accurate mineralogy,chronology,and geochemical studies,the genetic mechanism of the deposit is still unclear.Lithography,geochemistry,zircon U-Pb chronology and zircon Lu-Hf i-sotope analysis are carried out on the ore-forming host rock of the deposit.The results show that the ore-forming host rock was highly differentiated I-type granite and yttrium-rich light rare earth type granites(LREE/HREE=1.05～1.90,Y/REE=20.5％～32.0％)with high content of SiO2(76.11％～77.96％)and total alkali(K2O+Na2O)(7.18％～7.86％)contents,lower content of P2O5(0.01％～0.02％)and low value of Zr/Hf(18.73～26.97),Nb/Ta(5.29～11.10)and K/Rb(52.22～57.28)ratios.The ore-forming granites were formed in the Early Cretaceous((145.7±4.5)Ma),and the zircon Hf isotopic composition(eHf(t)=-0.21～+2.01)is significantly higher than that of the regional ancient crustal basement,indicating that there is a significant addition of neocontinental crust material in the magmatic source area,which is related to the exten-sional environment caused by the subduction and withdrawal of the regional paleo-Pacific plate.There are a large number of hydrothermal fluoro-carbonate rare earth minerals associated with fluorite in ore-forming granite,which are easy to decompose during weathering,providing the main source of ore-forming materials for ion-adsorbed heavy rare earth deposits.The discovery of Shitouping heavy rare earth deposit indicates that heavy rare earth de-posit can be formed after weathering of yttrium-rich light rare earth type granite in late Yanshanian in south China.
维普
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