湘东北地区伟晶岩型锂矿成矿模型及找矿潜力分析

The Metallogenic Model and Prospecting Potentiality of the Pegmatite Type Li Deposit in Northwestern Hunan Province

幕阜山地区在20世纪70年代发现了传梓源锂、铌钽矿床,近年来在该区黄柏山、窄板洞地区亦有富锂伟晶岩报导,但幕阜山地区锂矿资源尚未系统评价。锂矿资源作为新能源产业领域重要的原材料且需求日益增大,开展幕阜山地区锂矿成矿潜力分析尤为重要。本文通过对黄柏山地区、传梓源矿区和窄板洞地区含锂矿伟晶岩详细的野外地质调查,分析了含锂矿伟晶岩分布及含矿性特征,认为含锂伟晶岩在空间上远离幕阜山岩体分布,在垂向上锂矿化位于LCT型伟晶岩脉的上部。总结了湘东北地区铌钽矿伟晶岩和锂矿伟晶岩成岩、成矿年龄几近一致(140~130 Ma),稍晚于区内二云母二长花岗岩形成年龄(143~138 Ma),且同位素研究结果也指示花岗岩与伟晶岩有着相同的物质源区,认为区内二云母二长花岗岩为稀有金属伟晶岩成矿母岩,进而建立了伟晶岩型稀有金属矿成矿模型。依据成矿模型及区域稀有金属成矿的规律认识,建立了“传梓源式”伟晶岩型锂矿预测要素,首次对湘东北地区锂矿资源潜力开展预测评价,初步预测黄柏山—传梓源和窄板洞—梭墩锂矿远景区内锂矿资源潜力达10.19万吨,具备寻找大型锂矿产地(>10万吨)的潜力。

The rare metal deposits in Mufushan district, such as the Chuanziyuan Li-Nb-Ta deposit found in the 1970s and the Huangboshan and Zhaibandong Li deposits found in recent years, presently lack proper system evaluation targeting Li resources. However, Li is a key raw material in new energy industry development, with a growing demand. It is therefore necessary to analyze the metallogenic potential of the Li deposits in the Mufushan area. Using systematic field geological surveys of the Li-pegmatites in the Chuanziyuan, Huangboshan, and Zhaibandong Li deposits, this study analyzed the characteristics of the distribution and potentiality of the Li-pegmatites and showed that they are distributed far from the Mufushan batholith and that the Li mineralization occurs in the top the LCT-type pegmatites. Both the Li-pegmatites and Nb-Ta-pegmatites have the same diagenesis and mineralization ages(140~130 Ma), which occurred slightly later than the two-mica monzogranite(143~138 Ma). Furthermore, the pegmatites in this area have the same provenance as the two-mica monzogranite.Thus, here, we propose that the two-mica monzogranite could be the parental rock of the rare metal(Li-Nb-Ta)pegmatites and established the metallogenic model accordingly. Based on this forecasting model for the “Chuanziyuan” type Li deposit, we concluded that there are 101 900 tonnes of Li;O resources in the Huangboshan–Chuanziyuan and Zhaibandong–Suodun prospect area, showing that a large-scale Li deposit could exist in northwestern Hunan province.