Syntectonic magmatism and reactivation of collisional structures during late-Variscan shearing (SW Sardinia, Italy)

Abstract The Arbus igneous complex (SW Sardinia, Italy) represents a good example of short time lived post-collisional composite pluton emplaced at shallow crustal level in the external zone Variscan chain. almost consists granodiorite and leucogranite rock- suites 304 ± 1 Ma within main NW trending thrust separating metamorphic wedge from fold belt foreland. into dilatational step over connecting two NW–SE dextral shear zones which belongs to regional network strike-slip structures marking transition collision extension. microstructure observed for quartz K-feldspar confirms lack significant post-emplacement deformation, indicating only limited high-temperature sub-solidus recrystallization. Anisotropy magnetic susceptivity data field-structural analysis have been carried out reconstruct geometry trajectories magmatic flow relation deformation structures. Overall, fabrics are broadly discordant with foliation country rocks, defining an EW elliptical asymmetric sill rooted SW quadrant. reconstructed architecture combined petrologic observation indicates that accretion involved injection multiple dykes through sub-vertical feeder zone, lateral roof controlled by inherited collisional structure. duration activity cooling history contact aureole evaluated suite 2D thermal models. All these observations, together available geochronological constraints suggestive very rapid construction pluton. proposed emplacement model is fully consistent phase tectonics widespread magmatism accommodating large rotation Corsica-Sardinia block during Carboniferous-Permian transition.