赣南大埠岩体与象洞岩体元素地球化学特征对比及其对稀土成矿的指示OA

To explore the formation relationship between the granites and ionic rare earth deposits in Southern Jiangxi,this paper conducts a detailed comparative study of the geological context,petrological and geochemical characteristics,and patterns of mineralisation and enrichment of the rare earth deposits in the Dabu intrusion in southern Jiangxi,using the Xiangdong intrusion as a reference.Results show that the ore-forming parent rocks of both the Dabu and Xiangdong plutons are typical peraluminous high-K calc-alkaline rocks,exhibiting the typical characteristics of highly fractionated S-type granites.Both display significantly enrichment in Rb,Th,U,K,Nb,Nd,Zr,and Y,and strong depletion in Ba,P,Sr,and Ti,indicating crust-derived magma affinities.Moreover,the magma differentiation degree of the Dabu pluton is markedly higher than that of the Xiangdong pluton.Distinct differences exist in the total rare earth element contents,characteristic values,and partition patterns between the two plutons,suggesting that they may originate from different magma sources.The rare earth element distribution pattern of the weathered crust of the Dabu granite generally shows enrichment in light rare earth elements and depletion in heavy rare eatth elements,with an overall characteristic of being high on the left and low on the right.Combined with the trace element composition,these collectively indicate that the ore-forming materials of the Dabu rare earth deposit primarily originates from granites formed by partial melting of the crust.The weathered crust of the Dabu granite pluton presents obvious vertical zonation,with the rare earth element content showing a distribution pattern of depletion in the upper and lower parts and enrichment in the surface layer and middle part.The average total rare earth oxide content ΣRE2O3 in the middle completely weathered layer reaches 207.11 × 10-6,which is far higher than the industrial cutoff grade of rare earth ores,essentially constituting an industrial ore body.