Interplay of tectonics and neogene post-collisional magmatism in the intracarpathian region

Abstract Distribution of the Neogene calc-alkaline magmatism of the Carpathian arc is directly related in space and time to the kinematics of the two major terranes of the Intracarpathian area (Alcapa, Tisia-Getia) along the south-eastern border of the European plate. In the West Carpathians and adjacent areas, the volcanic activity occurred between 20–11 Ma, with large volumes of both acidic and intermediate rocks, generally distributed randomly, sometimes transversally to the orogenic belt and as rare small occurrences along the Flysch belt. In the East Carpathians, the volcanic rocks are distributed along the northern margin of the Zemplin block, the north–easternmost part of the Alcapa and eastward along the front of the Getic block, at the contact with European plate. Between Tokaj-Slanske-Vihorlat up to northern Calimani Mountains, the magmatism occurred between 14–9 Ma, and along the Calimani-Harghita chain between 9–0.2 Ma. The calc-alkaline magmatic rocks of the Apuseni Mountains are located in the interior of the Tisia block and occurred between 14–9 Ma. The generation of the calc-alkaline magmatism is considered here as the result of complex interplay between plate roll-back and lithospheric detachment tectonic processes and the break-off of the subducted plate, mostly in a post-collisional setting. (1) The magmatites of the Western Carpathians and the Pannonian basin were generated in direct relation to subduction roll-back processes, over the downgoing slab, during the period of lateral extrusion and back-arc extension. In this area, characterized by maximum crustal shortening, we can infer further delamination processes to explain the generation of magmas. (2) The magmatic rocks from the northern sector of the East Carpathians (Tokaj-Slanske-Vihorlat up to the Northern Calimani Mountains), resulted after subduction roll-back processes and an almost simultaneous break-off of the descending plate all along the arc segment during main clockwise rotation of the Intracarpathian terranes. (3) In the eastern sector of the East Carpathians (Calimani up to Harghita Mountains), the magmatic rocks were generated through partial melting of the subducted slab followed by gradual break-off of the subducted plate along strike (north to south). (4) The Apuseni Mts. magmatic activity resulted in transtensional tectonic regime by decompressional melting of lithospheric mantle, during the translation and rotation of Tisia-Getia block.