Formation of Li-Rb-Cs greisen-type deposit in Zhengchong, Jiuyishan district, South China: constraints from whole-rock and mineral geochemistry

The Jiuyishan complex located at Hunan Province, Jiuyishan district, South China, is composed of five granitic plutons (Xuehuading, Jinjiling, Pangxiemu, Shaziling and Xishan). The Zhengchong Li-Rb-Cs deposit is a greisentype deposit hosted by the Jinjiling granite, adjacent to the Pangxiemu granitic pluton. Based on textures, three types of greisen may be distinguished at Zhengchong: medium-grained massive greisen, feldspar-phyric greisen and quartz-phyric greisen. Detailed studies on field occurrence, petrographic observations, whole-rock and mineral geochemistry reveals that the Jinjiling granites represent the protoliths of the greisen mineralization and not the Pangxiemu granites. Metasomatic alteration of different phases of the Jinjiling granites formed at least three greisen types mentioned above. The medium-grained greisen and quartz-phyric greisen are totally altered, but the feldspar-phyric greisen are relatively less altered with residual feldspar phenocrysts. We also propose three main indications for ore deposit exploration in this area: future mineral exploration in the district should focus on the periphery of the Pangxiemu pluton, particularly along structures, where greisen alteration has been developed in places.