New constraints on the crustal structure and rifting processes of the Liguro-Provençal Basin, Western Mediterranean

Geophysical data from the Liguro-Provençal Basin show prominent margin asymmetry but the nature of the crust, especially in the northeastern part of the basin, remains unclear. The basin formed at the junction of the northern Apennines and the western Alps due to the rollback of the Calabrian-Apennines subduction zone in the Oligo-Miocene. The opening of the basin was accompanied by counter-clockwise rotation of the Corsica-Sardinia block relative to Europe with the basin widening southwestwards. Recent weak compressional earthquakes offshore within the basin suggest possible basin inversion due to the ongoing Africa-Eurasia convergence. An insight into the crustal structure of the basin is therefore the key to understanding these recent processes. To this end, we compiled existing geological and geophysical data, including new data from the German project “Mountain Building Processes in Four Dimensions” (4DMB), to constrain the crustal and sedimentary thicknesses throughout the basin. Moreover, we derived kinematic parameters of extension using regional tectonic reconstructions and used the coupled ASPECT and FastScape geodynamic code to model the opening of the basin in its northeastern (Corsica – Provence) and southwestern (Sardinia – Gulf of Lion) parts. The comparison of the geodynamic models and geophysical data suggests: 1) the extent of oceanic crust in the Liguro-Provençal Basin did not reach as far north as previously presumed; 2) rift-related structures are possibly being reactivated offshore to the northwest of Corsica. We also present new constraints on the lateral extent of rifted continental crust and exhumed mantle and evolution of the basin through time.