Structure of the Variscan metamorphic complexes in the central transect of the Posada-Asinara Line (SW Gallura region, Northern Sardinia, Italy)

Abstract

This study represents the first detailed tectono-metamorphic map of the metamorphic complexes cropping out in the inner portion of the Variscan belt in north-central Sardinia Island (Italy). The Main Map is at a 1:30.000 scale and covers an area of c. 148 km². It is based on 1: 10.000 scale classic field mapping and represents an overview of the lithological and structural complexities documented in the metasedimentary and migmatite domes cropping out along the central transect of the Posada-Asinara Line (PAL). The PAL is a crustal scale discontinuity that divides migmatites from the metasedimentary sequences affected by greenschist- to amphibolite-facies metamorphism. The map shows the orientations of the superimposed foliations, fold axes and mineral lineations on the basis of geometric crosscutting relationships and, for the first time, the location of ductile-brittle and brittle shear zones developed during the long-lived activity of the Posada-Asinara Line.

Keywords:

• Sardinia
• Variscan belt
• mylonites
• Posada-Asinara Line

Acknowledgements

I thank Giedrė Beconytė for its comments on the map and Elena Druguet and Marcello Franceschelli for their detailed comments on both the manuscript and the map. I also thank Michele Zucali for editorial handling. Thank R. Carosi for financial support during the field work.