Devonian/Mississippian I-type granitoids in the Western Carpathians: A subduction-related hybrid magmatism

Abstract SIMS zircon U–Pb dating of I-type granitoids from four Variscan crystalline basement outcrops in the Western Carpathians (Tribeč, Nízke Tatry, Čierna Hora and Slovenské Rudohorie Mts.) implies that they originated between 367 and 353 Ma. Therefore, they belong to the earliest Variscan I-type granitoids. The oldest Devonian age at ca. 367–364 Ma is obtained from an enclave-bearing tonalite and associated dikes of the Tribeč Mts. Several granodiorites from the Nízke Tatry, Vepor and Čierna Hora Mts. (353–357 Ma) show younger, Early Carboniferous ages. These data require a re-assessment of older models that explained the genesis of I-type granitoids in the Western Carpathians based on the assumption of younger, Middle to Upper Carboniferous ages. The I-type granite massifs of the Western Carpathians most probably originated in an arc-related environment within the Galatian superterrane, an assemblage of Gondwana derived fragments. The early age of I-type magmatism in the Western Carpathians marks the beginning of a north-dipping subduction of the Paleotethys ocean under Ibero-Ligerian and intra-Alpine terranes. We suggest a term “Proto-Tatricum” for that part of the Galatian superterrane where Devonian/Mississippian I-type granitoids were emplaced. Now the granitoids are incorporated as a part of crystalline basement into the Alpine Tatric and Veporic units within present West-Carpathian mountain chain.