Structural constraints on active and Late-Quaternary relic landforms in the Gulf of Genoa (Ligurian Sea, Italy): new evidence from CARG survey

The integration of existing seismic data with new ultra-high-resolution Sparker lines and processed multibeam bathymetric data, collected within the framework of the Italian CARG Project, enabled a detailed reconstruction of the geological setting and the Late Quaternary evolution of coastal environments on the continental shelf of the Gulf of Genoa. This study allowed a reconstrucion and mapping of the stratigraphic characters of Late Quaternary deposits (facies, thickness, distribution), the shelf’s paleo-morphology (barriers, terraces, channels, pockmarks, cliffs) and recent or active morphodynamic processes (erosion, mass wasting, fluid escape) and related structural conditioning (inherited faults and recent tectonics). The data show active erosion and landslide scars affecting several sectors of the shelf edge delimiting the heads of the Polcevera and Bisagno canyons, while in others cases, a thin layer of Holocene mud (HST) covers a paleoshelf break, mainly formed during the Last Glacial Maximum.Along the shelf edge bordering the canyon heads, small subcircular bedrock highs and small depressions interrupt the flat shelf morphology. Based on seismic line interpretation, these features are interpreted as mud volcanoes and pockmarks linked to deep-seated fluid escape, which often coincide with the main Mio-Pliocene blind faults. The identified fluid escape phenomena influence the seabed instability, favouring in some sectors the retreat of canyon heads.The new structural setting reconstruction of this sector of the Ligurian margin, marking the Alpine–Apennine margin transition, is characterised by NW–SE and NNE–SSW fault systems that delimit several Upper Miocene–Pliocene grabens within the shelf.The results, including high-resolution mapping and stratigraphic analysis, provide valuable information for paleogeographic reconstructions, archaeological studies of the Late Quaternary and are invaluable tools for geohazards analysis and forecasting, as well as engineering planning and coastal infrastructure projects.