1: Subduction, slab detachment and mineralization: The Neogene in the Apuseni Mountains and Carpathians Franz Neubauer a, * , Andor Lips b , Kalin Kouzmanov c , Jaroslav Lexa d , Paul Iva ˇ zcanu c,e a Department of Geography, Geology and Mineralogy, University of Salzburg, Hellbrunner Str. 34, A-5020 Salzburg, Austria b Mineral Resources Division, BRGM, av. C. Guillemin, F-45060 Orle ´ans cedex, France c Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH-Zentrum NO, CH-8092 Zu ¨ rich, Switzerland d Slovak Geological Survey, Mlynska ´ dolina 1, SKO-81704 Bratislava, Slovakia e Romanian Geological Survey, Caransebes Street 1, RO-79 678 Bucharest 32, Romania Received 19 November 2004; accepted 21 April 2005 Available online 13 October 2005 Abstract The Inner Carpathians comprise several distinct Neogene late-stage orogenic Pb–Zn–Cu–Ag–Au ore districts. The mineral deposits in these districts are closely related to volcanic and subvolcanic rocks, and represent mainly porphyry and epithermal vein deposits, which formed within short periods of time in each district. Here, we discuss possible geodynamic and structural controls that suggest why some of the Neogene volcanic districts within the Carpathians comprise abundant mineralization, while others are barren. The Neogene period has been characterized by an overall geodynamic regime of subduction, where primary roll-back of the subducted slab and secondary phenomena, like slab break-off and the development of slab windows, could have contributed to the evolution, location and type of volcanic activity. Structural features developing in the overlying lithosphere and visible in the Carpathian crust, such as transtensional wrench corridors, block rotation and relay structures due to extrusion tectonics, have probably acted in focusing hydrothermal activity. As a result of particular events in the geodynamic evolution and the development of specific structural features, mineralization formed during fluid channelling within transten- sional wrench settings and during periods of extension related to block rotation. In the Slovakian ore district of the Western Carpathians, Neogene volcanism and associated mineralization were localized by sinistral, NE-trending wrench corridors, which formed part of the extruding Alcapa block. The Baia Mare ore district, in the Eastern Carpathians, reflects a transtensional wrench setting on distributed oversteps close to the termination of the Dragos Voda fault. There, mineralization was spatially controlled by the transtensional Dragos Voda master fault and associated cross- fault systems. The Golden Quadrangle Cu–Au ore district of the Southern Apuseni Mountains reflects an unusual rotated transtensional/extensional setting close to the termination of a graben system. There, fluid flow was probably localized by fault propagation at the inner tip of the graben system. The spatial and temporal evolution of the magmatism and its changing geochemical signature from (N)W to (S)E strongly suggests a link with the contemporaneous northeastward roll-back of the subducted slab and a progressive southeastward detachment during accelerating roll-back. This geodynamic evolution is further supported by the present-day overall and 0169-1368/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.oregeorev.2005.07.002 * Corresponding author. E-mail address: franz.neubauer@sbg.ac.at (F. Neubauer). Ore Geology Reviews 27 (2005) 13 – 44 www.elsevier.com/locate/oregeorev