Geology, mineralization, and fluid inclusion characteristics of the Meliksu reduced tungsten skarn deposit, Alai Tien Shan, Kyrgyzstan: Insights into conditions of formation and regional links to gold mineralization

摘要

The Meliksu W skarn deposit (similar to 10Kt WO3, with average grade of 6.6% WO3) in the Alai Segment of the Southern Tien Shan is related to an Early Permian granitoid pluton that comprises ilmenite-series to ilmenitetitanite-bearing, medium-K, metaluminous to peraluminous I-type granitoid (monzonite/diorite-tonalite-granodiorite to granite) rocks. There is a regional-scale continuum from these intrusions to transitional weakly reduced to weakly oxidized metaluminous I-type granitoid suites accompanied by reduced intrusion-related Au deposits. Magmatic evolution also included coeval high-K to shoshonitic suites, and younger Early Permian, post-collisional to within-plate, alkaline (from monzogabbro to nepheline syenite) and carbonatite intrusions, indicative of an extensional tectonic regime. Consistent with this evolution toward an extensional environment, reduced W skarns and associated reduced intrusion-related Au mineralization in the region may evolve toward Sb-Hg (+As, Au, W) mineralization exhibiting the Carlin-type affinity.