Age and petrogenesis of the newly discovered Early Permian granite 3 in the Kumtor gold field, Kyrgyz Tien-Shan

Permian intrusions are widespread in the Middle and Southern Tien Shan, with fewer occurrences in the Northern Tien-Shan. Notably, many of these intrusions are spatially associated with a variety of ore deposits, indicating a significant link between magmatic activity and mineralization processes in these areas. We studied granite samples recently recovered from drilling in the Kumtor gold field to evaluate their potential relationships with gold mineralization. We report major and trace element geochemistry, zircon U-Pb age and Hf isotope data for this so-called Kumtor granite. The Kumtor granite is metaluminous to peraluminous and belongs to the high-K and calc-alkaline series with I-type geochemical characteristics. The relatively high K₂O and Na₂O concentrations and low high field strength elements (HFSE) and heavy rare earth elements (HREE), the presence of biotite within these I-type granites, together with their low zircon saturation temperatures (731–779 ℃), suggest that they were likely derived from a hydrous source formed by dehydration melting of mica-bearing, medium- to high-K metabasaltic rocks. Our zircon U-Pb dating results indicate that the Kumtor granite intruded at 293 ±1.7 Ma, which is consistent with the age range of other Middle Tien-Shan granitoids. The zircon Hf isotopic composition is εHf_(t) = –7.56 to –5.05, indicating an ancient (1.39 to 1.52 Ga) crustal origin. Petrographical, geochemical and geochronological data indicate that the Kumtor granite is similar to leuco-granites of the Terekty complex. Our results indicate that the Kumtor granite was emplaced in the early Permian in a post-collision setting and may have temporal and genetic relationships with gold mineralization.