Numerical modeling of post-collisional carbonated alkaline magmatism: Variscan style Orogeny (the Ivrea Zone as natural laboratory)

摘要: Abstract The Ivrea Zone of northwest Italy exposes a section the lower crust and lithospheric mantle deformed during Variscan Orogeny, where series carbonated alkaline pipes was emplaced over time span ca. 40 Ma, following crustal underplating event at 288 Ma. We use coupled 2D petrological-thermomechanical approach to geodynamically model processes that led continental collision subsequent emplacement with application craton margin metasomatic events. criteria are assessed develop generic model: 1) closure Rheic Ocean through subduction oceanic subduction-related metasomatism mantle, 2) high-temperature metamorphism associated collision, preceding 3) event, 4) partial melting metasomatized domains gravitational collapse orogen source pipes. Our investigates process by varying thermal ages intervening (40, 60, 80 Ma) changing rheological strength crust. employ two ideal end-member cases, wet quartzite plagioclase An75, an intermediate dry quartz case represent migmatized crust, polymineralic cases felsic granulite mafic as possible representations specifically. discuss results three scenarios controlled age rheology can reproduce tectonic scale features observed in Zone. Scenario 1: 40 Ma widespread H2O CO2 fluxes within mantle. displays little melt productivity due presence overthickened decouples peels off beneath colliding terrane. 2: An75 60 Ma shows reproduces is precursor genesis permissive for but relative timings misplaced. 3: 80 Ma recreates relationships between followed initiation magmatic lastly localized This potentially explain prevailing hypotheses formation Whereas all models reproduced different stages tectono-magmatic evolution only scenario 3 could sufficiently recreate sequence events Scenarios 1 2 may provide precious information about nature timing implications enhanced prospectivity wide range ore systems specific along margins blocks.