Evolution of the Corsica-Sardinia Batholith and late-orogenic shearing of the Variscides

The Corsica-Sardinia Batholith formed in the late Carboniferous-Permian along the northern Gondwana margin. One or more of the following processes may have raised the Variscan geotherm enhancing melting of the crust and uppermost mantle, such as: i) break-off and detachment of the Rheic oceanic slab, ii) mantle delamination due to gravitational re-equilibration of thickened crust, iii) shear heating, and iv) advection of mantle-derived melts. In this paper, we present a simple onedimensional thermal model to explain the origin of the batholith in a geodynamic setting consistent with intraplate shearing between Gondwana and Cadomian-Avalonian blocks. Input parameters, and boundary and initial conditions of the model crust are derived from a careful re-examination of large petrological, geochronological, and structural datasets. All parameters are varied within a range of geologically realistic values to reproduce thermal histories related to different tectonic processes, and the reliability of models is quantitatively evaluated by comparing the simulated geotherms with a large dataset of pressure-temperature-time (P-T-t) constraints. The best fit to P-T-t constraints is obtained for: i) break-off in the Late Devonian-Early Carboniferous, ii) decreasing exhumation rates from 340 to 280 Ma, and iii) transpression at high average strain rates, mostly coeval with the peak of high-T-low-P metamorphism.