Outline of the Variscan basement of Sardinia

In Sardinia a quasi-complete section of the southern branch of the Variscan orogenic belt crops out, characterized by non-metamorphosed to high-grade rocks, whose age ranges from Early Cambrian to Early Carboniferous, and that are involved in a complex polyphase deformation. The main result of the Variscan orogeny in Sardinia is a tectono-metamorphic partition with, from north to south: an Inner Zone, with medium to high grade metamorphism, thrusted over a Nappe Zone, with green schist metamorphism that overthrusted a Foreland Zone affected by very low grade regional metamorphism. The pre-Variscan succession is well exposed in the Foreland and Nappe zones where four main synthemes can be recognized: i) a Lower Cambrian to Lower Ordovician terrigenous and carbonatic succession deposited in the Gondwana passive margin, sealed by an angular unconformity related to the Sardic Phase, ii) a Middle-Upper Ordovician magmatic complex, both intrusive and effusive, probably related to an Andean-type plate convergence, iii) a terrigenous to carbonatic succession from Late Ordovician to Early Carboniferous, again related to a passive margin evolution; iv) finally a flyschoid Culm-like succession accredited to Early Carboniferous.