Polyphasic deformation of the Mesozoic and tertiary succession in the Supramonte (Eastern Sardinia) [Deformazione polifasica della successione mesozoica e terziaria del Supramonte (Sardegna orientale)]

During Tertiary, the Palaeozoic crystalline basement and the Mesozoic-Lower Eocene cover of Eastern Sardinia, have been affected by a transcurrent tectonics, with contemporaneous development of both transpressive and transtensive structures. Recent geological survey carried in the Supramonte area and a more detailed structural analysis also supported by 3D geological modeling, allow us to recognise a more complicated architecture that involved both thrusts and related folds and strike-slip faults. At first the rigid basement blocks was displaced along planar, high angle reverse faults and the sedimentary Mesozoic cover was deformed as a forced-folding system. After that the sinistral strike-slip faults, and related structures, clearly post-date the thrust. Therefore, a two stage of evolution can be supposed, probably related to the same geodynamic evolution related to the deformation of a rigid crustal block with a sedimentary cover, bounded by E-W dextral transpressive strike-slip faults and NE-SW sinistral strike-slip faults, pushed-upward and toward the east.