Late Cretaceous magmatic controls on epithermal-porphyry and volcanogenic massive sulfide systems in the Eastern Pontides, Northeast Türkiye: geochemical and geochronological evidence

Abstract The Late Cretaceous magmatic arc of the Eastern Pontides consists of two magmatic cycles. Turonian to Santonian (93.9 to 83.6 Ma) submarine dacitic to rhyolitic rocks host major volcanogenic massive sulfide (VMS) deposits. By contrast, the degree of fertility of Campanian (83.6 to 72.1 Ma) intermediate to felsic rock sequences of the second cycle is still an open question. In particular, the nature, the absolute age, and the genetic relationship of Late Cretaceous epithermal systems with respect to the two magmatic cycles and the VMS deposits is still a matter of debate. The Yanıklı prospect, Artvin district allows us to demonstrate the fertility of the Campanian magmatism. Its intermediate-sulfidation epithermal nature is supported by its hydrothermal alteration pattern, mineral paragenesis, fluid microthermometry and stable isotope characteristics, and sphalerite chemistry. Uranium-lead zircon ages of 82.3 ± 0.4 and 81.6 ± 0.4 Ma and a 40 Ar/ 39 Ar adularia date of 78.6 ± 0.8 Ma indicate a Campanian age for both the immediate host rocks and ore formation at Yanıklı. Whole-rock geochemistry indicates that the immediate host rocks at Yanıklı belong to the second Late Cretaceous magmatic cycle of the Eastern Pontides. In this study we demonstrate a lithogeochemical, geodynamic, and metallogenic transition at ~ 83 Ma between the two Late Cretaceous magmatic cycles. The Turonian-Santonian tholeiitic to calc-alkaline magmatism in a back-arc basin setting resulted in the formation of VMS deposits, whereas the Campanian high-K calc-alkaline to shoshonitic magmatism in a continental arc environment resulted in the emplacement of epithermal-porphyry systems.