Tectonic controls on volcanism in transfer fault zones: Insights from the Catalan Volcanic Zone (Northeastern Iberia)

Transfer fault zones are commonly associated with volcanic activity. While geochronological methods such as the U Pb and Ar Ar dating have been traditionally used to establish the absolute timing of volcanism, recent advances allow us the dating of fracture-filling minerals. However, integrated tectono-volcanic and geochronological studies of fault zones are scarce, limiting our ability to constrain accurately the evolution of fault-controlled volcanic zones. This paper reviews the tectono-volcanic history of northeastern Iberia through the geochronological and kinematic analysis of well-known examples of Neogene to Quaternary fault zones with associated volcanism along the Transverse Ranges. These fault zones are located at the northwestern tip of a NW-SE transfer zone that segmented the Liguro-Provençal Rift. We integrate available geological and geophysical data with new structural analysis of meter scale fractures across three fault zones and U Pb dating of fracture-filling carbonates. The U Pb dating of fracture-filling calcite reveals early Eocene strike-slip faulting at ~49 Ma, during the Alpine compression, and synchronous strike-slip and extensional dip-slip faulting from ~22 to ~2 Ma, coinciding with the Liguro-Provençal rifting. We propose a new lithospheric-scale model in which faults acted as sub-vertical conduits for the ascent of magmas sourced from the lithosphere-asthenosphere boundary, based on the composition of recovered xenoliths. Our geochronological dataset supports the hypothesis that fault reactivation governs the timing, location and migration of volcanism in the Neogene to Quaternary Catalan Volcanic Zone, which was additionally influenced by lithospheric thinning and the development of transfer fault zones that potentially reflect the reactivation of Mesozoic structures. These processes share striking similarities with those observed in the western Mediterranean Region, the European Cenozoic Rift System, and other extensional systems worldwide, highlighting the role of inherited transfer fault zones in the evolution of volcanism.