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.
万方数据
维普
