Tectonic Interplay in the Gulf of Cagliari (Italy): Extension, Compression and Strike‐Slip Movements

The Gulf of Cagliari (CG) region has been shaped by a combination of extensional and compressional tectonics, sometimes accompanied by transpression, since at least the Paleogene. The Corso-Sardinia Plate underwent counterclockwise rotation during the Late Oligocene-Early Miocene and coeval extensional tectonics formed the Sardinian Rift, which propagated into the present-day CG region. Simultaneously, compressional structures developed at the southeastern margin, starting the collision with the northern Africa margin. The Banghittu and Ichnusa highs, underlain by Palaeozoic basement, were uplifted and subsequently partially buried by thick Oligo-Miocene (OM) sedimentary wedges. Starting in the Late Miocene onwards, the southern Campidano Graben partially reactivated the pre-existing faults of the Sardinian Rift in the CG area. A Messinian evaporitic sequence (200–300 ms TWT of gypsum thickness) was deposited, thinning toward the margins. At the Last Messinian, a deep canyon eroded the gypsum within the graben depocenter, which was subsequently filled by Pliocene sediments. Compressional tectonics resumed at the Pliocene-Quaternary boundary (Ao phase), probably due to collision with a thick African continental foreland. The Banghittu High, ENE-WSW trending, was disrupted by the extensional deformation of the Campidano Graben and is now mostly buried below the Plio-Quaternary (PQ) sediments partially transported through recent canyons. In contrast, the Ichnusa High remains exposed, shaping the southern margin of the gulf with its NE-SE elongated form related to SE-ward compression. Its approximately symmetrical section also suggests a Quaternary strike-slip component. During the Quaternary, a canyon system was re-established, with trajectories partially determined by the previous structural highs.