The review of recent bathymetric and geophysical data collected in the framework of several research and cartographic projects have allowed a detailed reconstruction of the morpho-structural setting and the (neo)tectonic evolution for both the Alpine and Apennine margins of the Ligurian Sea (Italy). The widespread occurrence of erosional processes and sediment mass movements along the steep continental slope and within the system of submarine canyons reflect the close correlation between the active tectonics and the recent morpho-dynamic evolution of the Ligurian Margin. This relation is better constrained in the western sector (Alpine) of the Ligurian Sea, where the recent uplift of the continental margin is associated to a well-developed system of inherited structures reactivated under a compressive/transpressive regime and widespread seismicity. In the eastern sector, where the seismicity is lower or absent, the mass movements are limited to few areas (e.g., the Portofino slope) coinciding with seismic clusters. Additionally, this sector is characterized by moderate and episodic fault reactivations under a compressive regime. The evidence of compressive deformation along the inherited fault systems has been revealed in some areas of the Ligurian Sea where the post-drifting extensional tectonics is interrupted by episodic tectonic inversion (at least) during the Middle–Upper Miocene and the Plio–Pleistocene until present.
Deep-seated gravitational slope deformation (DsGSD) represents a relevant geological-geomorphological feature of the landscape and has drawn scientific attention for the past several decades. During a detailed fieldwork in the Ligurian Alps, we identified areas (larger than ca 5 km2), characterized by very low percentage of outcrops, with rock blocks on the watershed and many morpho-tectonic evidences. Through the integration of geological-geomorphological mapping, structural data, photo interpretation, GIS-based analyses, we identified a number of typical DsGSDs. The example here described is one major complex-sagging-type DsGSD that is not present in national land planning and/or management databases but that is likely at the origin of the large-scale landslides which affected the villages of the area. This DsGSD is also located within the Beigua UNESCO Global Geopark, in an area of unique natural and historical value. This study once again highlights the importance of ground truth observations as the basis for further investigations.
This new map at 1:25,000 scale covers an area in the Western Alps (Italy), where the HP metamorphic basement is covered by a (predominantly clastic) late- and post-orogenic upper Eocene-lower Miocene cover. This provides unequivocal evidence that exhumation of the metamorphic units was accomplished by the lower Oligocene. The basement is made up of tectonic units with different metamorphic peaks that coupled during the exhumation path. Both basement and cover are affected by long-wavelength, asymmetric folds and thrust faults with top-to-E-NE vergence; this deformation phase has long been interpreted as linked to the rotation of the Corsica-Sardinia block and contemporary opening of the Liguro-Balearic basin and beginning of the Apennine orogeny. We particularly investigated some of these structures that crop out in the mapped area to give further constraints on their distribution, type and kinematics and to frame them in a larger picture of left-hand strike-slip tectonics.
12 September 2025 in Journal of Structural Geology