茶卡北山锂辉石花岗伟晶岩锂矿化特征及成矿时限

锂是重要的战略金属矿产，锂辉石花岗伟晶岩是锂矿资源的重要来源。近来柴北缘茶卡北山地区新发现锂辉石花岗伟晶岩脉群，本文对区内锂辉石花岗伟晶岩进行了岩相学、矿物学、矿物化学、年代学研究工作，确定了锂辉石花岗伟晶岩的矿化特征及矿化年限。锂辉石花岗伟晶岩存在两期矿物组合：早期由粗粒锂辉石、粗粒钾长石、粗粒白云母、粗粒更(钠)长石、粗粒石英和铌钽铁矿等组成，属熔体结晶阶段产物；晚期由锂绿泥石、富锂云母、蠕虫状锂辉石和细粒他形石英等组成，为岩浆期后热液交代产物。根据两期矿物组合判断存在两期锂矿化，认为早期锂辉石的局部蚀变与晚期锂矿物的形成指示体系内存在锂的活化和再沉淀过程。测得与锂辉石伴生的铌钽铁矿U-Pb年龄为241.0±1.3 Ma,可代表锂辉石花岗伟晶岩熔体结晶年龄，即为早期锂成矿年代，矿床为印支期产物。

Lithium mineralization characteristics and chronology of spodumene granite pegmatite in the northern Chaka Mountain, Qinghai Province

Lithium is an important strategic metal mineral, and spodumene granite pegmatite is an important source of lithium resources. Recently, the spodumene granite pegmatite group has been newly discovered in Chaka Mountain area of the northern margin of Qaidam. This paper determines the mineral formation, evolution and mineralization age of spodumene granite pegmatites through petrography, mineralogy and chronology. The spodumene granite pegmatite has two phases of mineral assemblages. In the early stage, there are coarse-grained spodumene, coarse-grained K-feldspar, coarse-grained muscovite, coarse-grained plagioclase, coarse-grained quartz and coltan, which belong to the product of the melt crystallization stage. The late stage is composed of cookeite, Li-rich mica, wormlike spodumene and fine allomorphic quartz, which is the product of post magmatic hydrothermal metasomatism. Therefore, it can be inferred that there are two stages of lithium mineralization, and the local alteration of early spodumene and the formation of later lithium minerals indicate that there is a process of lithium activation and reprecipitation in the system. The coltan associated with spodumene gives a U-Pb age of 241.0 ± 1.3 Ma, indicating that the melt crystallization age of the spodumene granite pegmatite is the early lithium mineralization age, and the ore body is the product of Indosinian period.