THE PALEOZOIC BASEMENT OF MONTE GRIGHINI UNIT, A DEEP VIEW IN THE NAPPE STRUCTURE OF VARISCAN BELT IN SARDINIA. SYNTHESIS OF GEOLOGICAL DATA AND FIELD GUIDE

The Monte Grighini Complex (MGC; central-west Sardinia) is a metamorphic complex belonging to the Nappe Zone of the Sardinian Variscan belt, located at the northwestern end of the Flumendosa Antiform. It consists of three tectonic units, among which Monte Grighini Unit represent the deepest of the whole nappe zone, and a kilometer- wide shear zone with synkinematic granitoid intrusion. We present a guide for a two days field trip. The first day will be mainly focused on the metamorphic rocks of Monte Grighini Unit, and mylonitic leucogranite with S-C fabric together with other interesting structures (i.e. a giant quartz dyke). The second day will be developed along the mylonite/cataclasite belt on the southwestern side of the complex. The field guide is preceded by a brief, updated excursus on Sardinian Variscan basement and by a detailed description of the complex from the most recent papers.