Deformed mafic microgranular enclave in the sheared Ordovician granodioritic orthogneiss.

On the road from Torpè village to Lodè (S. Anna villages) there is an outcorp of staurolite and garnet bearing micaschist: near the gate at the entrance of a small forest track, we see cm-sizestaurolite and garnet porphyroclasts on the S2 foliation of the micaschist. Garnet and staurolite grew after the D1 and from pre-to syn-D2 deformation phase.

S-C-C’ fabric in Ordovician orthogneiss, top-to-the NE sense of shear and thin section photo (II nicols).

On the road near of «Cantoniera Mt. Tundu» we start to see outcorps of granodioritic orthogneiss with a prominent C-S fabric and C’ structures pointing to a top-to-the NW sense of shear (“dextral”).

Kyanite bearing micaschist, Bruncu Nieddu.

About 0.5 km further north along the track we reach the kyanite+biotite isograd withmm- to cm-size bluish kyanite crystals in the matrix of the mylonites and in quartz-rich veins (Fig. 1). The kyanite+biotite isograd is marked by the first appearance ofkyanite crystals. The rocks consist of porphyroblasts of staurolite, kyanite, andplagioclase enveloped in a mylonitic matrix of muscovite, biotite, chlorite, and ilmenite. Temperatures up to 595 °C and pressures up to 0.67 GPa have been reported byFranceschelli et al. (1989), and pressures over 0.9 GPa by Carosi & Palmeri (2002) for the metamorphic peak.