广东离子吸附型稀土矿床特征及找矿预测

Characteristics and Prospecting Prediction of Ion Adsorption Rare Earth Deposits in Guangdong Province

稀土是我国的优势矿种,尤以华南地区离子吸附型稀土矿产资源最为突出,广东省内的风化壳离子吸附型稀土矿床主要分布在韶关、河源、梅州、清远、潮州、揭阳、肇庆和茂名等地。水系沉积物地球化学异常是圈定矿床找矿远景区最有效且快速的一种手段,本次研究以广东省1∶20万水系沉积物地球化学数据为基础,将镧(La)和钇(Y)分别作为轻稀土(LREE)和重稀土(HREE)的特征元素,选取了34处稀土异常调查区(其中LREE异常区15处,HREE异常区19处),通过对人工剥土和人工冲击钻采样分析,初步评估了相应的稀土成矿潜力。139件样品分析结果显示,114个样品达到边界品位(≥0.02%),占送样总数的82.0%;71个样品达到工业品位(≥0.04%,最高可达0.27%),占送样总数的51.1%,新发现韶关乳源、潮州钱东、汕尾碣石、河源东源和河源龙川5个找矿远景区。为了更有效地圈定离子吸附型稀土矿床,结合稀土矿床找矿预测的标志,建议在1∶20万水系沉积物稀土元素地球化学异常区的基础上,开展低密度不规则网土壤地球化学测量,进一步浓缩异常范围并圈定离子吸附型稀土矿床找矿远景区,系统建立稀土资源潜力评价体系。

Rare earth elements(REEs)are the dominant mineral species in China,especially the ion-adsorption rare earth deposits widely distributed in South China.The ion-adsorption REE deposits in Guangdong province are distributed mainly in the Shaoguan,Heyuan,Meizhou,Qingyuan,Chaozhou,Jieyang,Zhaoqing,and Maoming areas.Geochemical anomalies of stream sediment surveys are an efficient and rapid method for prospecting targets of metal deposits,but the effectiveness of this method for delineating prospecting targets of ion-adsorption REE deposits has not been verified.In this study,34 REE survey areas were selected according to the lanthanum(La)and yttrium(Y)geochemical anomalies of the 1︰200000 stream sediment survey(including 15 LREE and 19 HREE).The mineralization potential of the above areas were evaluated through analyses of samples obtained through manual stripping and artificial percussion drilling.The analytical results show that 114 out of 139 samples collected from the weathering crusts have contents of rare earth oxides(REO)higher than the cutoff grade(≥0.02%),accounting for 82.0%of the samples;71 samples reach industrial grade(≥0.04%),accounting for 51.1%of the samples,and the contents of REO can be up to 0.27%;and five ore prospecting areas have been delineated,i.e.,Ruyuan in Shaoguan,Qiandong in Chaozhou,Jieshi in Shanwei,Dongyuan,and Longchuan in Heyuan.Thus,according to the prospecting prediction signs of REE deposits,on the basis of the 1︰200000 stream sediment geochemical anomalies of rare earth elements,we propose that soil geochemical survey of low density irregular sampling grid can further concentrate the anomalous range,delineate REE prospecting targets,and contribute to the establishment of a REE resource potential evaluation system.