Geochemistry and Genesis of Rare Metal (Sn-W) Cherdoyak Deposit, Eastern Kazakhstan

This study presents new data on the Cherdoyak Sn–W deposit in Eastern Kazakhstan. The deposit is spatially associated with the northeastern contact of the Cherdoyak granite intrusion and comprises a stockwork of quartz veins and greisen bodies developed within the earlier-emplaced Kunush granite intrusion. Three granite varieties were distinguished: (1) biotite plagiogranites of the Kunush massif, (2) first-phase biotite granites of the Cherdoyak intrusion, and (3) second-phase muscovite granites and leucogranites of the Cherdoyak intrusion. The Kunush granites underwent extensive graphitization and greisenization, resulting in the development of stockwork-type Sn–W–As mineralization composed of cassiterite, scheelite, and arsenopyrite. The crystallization ages of the granites were determined by U–Pb zircon geochronology and yielded ages of 296 Ma for the Kunush intrusion, 290 Ma for the first-phase Cherdoyak intrusion, and 289 Ma for the second-phase intrusion. Muscovite from the Cherdoyak greisens yielded an Ar/Ar age of 280 ± 5 Ma. The available geochronological and geochemical evidence suggest a genetic relationship of Cherdoyak deposit with the emplacement and magmatic evolution of the Cherdoyak intrusion. Ore formation was driven by advanced fluid–magma differentiation during the evolution of the Cherdoyak magmatic system.