3D Architecture and Plio-Quaternary evolution of the Paola Basin: New insights to the Forearc of the Tyrrhenian-Ionian Subduction System

The 3D stratigraphic architecture and the Pliocene to Quaternary evolution of the Paola Basin (offshorewestern Calabria), a segment in the fore-arc of the Tyrrhenian-Ionian subduction system, are reconstructedby using a grid of unpublished of multi-channels, high-penetration, seismic-reflection profiles acquired inthe frame of the project SINBUS, integrated by bathymetric data from EMODnet-Bathymetry portal. ThePaola Basin is a NNW-SSE elongated, ~ 60 km long and ~20 km wide, slightly asymmetric syncline, whichhosted Plio-Quaternary deposits up to 5.5 km thick in its depocenter. The Plio-Quaternary sequence shows aneastward progradational internal geometry that becomes sub-horizontal in the uppermost part. The geometriesof deposits suggest that the source area for sediments had to be localized, at first, in the West or North-westernsector of the basin, and in the Coastal Chain during the late stage of the basin evolution. Post-Messiniantectonic shortening of reflectors is less than 5% in both the directions of the principal axes of the basin, andthus it is negligible. Tectonic features associated with strike-slip restraining and releasing bends are interpretedalong the western sector of the basin. They form a NS-trending and geomorphically prominent ridge separatingthe Paola Basin from the central sector of the Calabrian margin. The area of the future Paola Basin and itseastern prolongation until the western flank of the Sila Massif was affected by subsidence during and after theMessinian time. At ~ 3.5 Ma, subsidence persisted in the Paola Basin segment, while the area corresponding tothe Coastal Chain and the Sila Massif uplifted. As a consequence, a regional scale asymmetrical syncline (PaolaBasin) and anticline (Coastal Chain and the Sila Massif) developed. Also, normal faults formed in the hingezone of the anticline and the Crati Basin nucleated. Based on the wave-length and position of the maximumamount of vertical movements experienced by the fore arc segments affected by subsidence and uplift as wellas the lack of significant faults bordering the Paola Basin, the formation of these features could be related atthe flexure of the upper plate in response to the subduction system dynamics and sediment load. The strainpartitioning into strike-slip fault zones occurred in response to the oblique subduction of the Adriatic-Ionianplate. On the basis of the strike-slip fault zones recognized to the west of the Paola Basin and documented byseveral authors along the northern Calabrian Arc as well as the lack of significant internal deformation withinthe sedimentary infill of the Paola basin, the fore arc basin of the Tyrrhenian-Ionian subduction system can beclassified as a neutral accretionary-type forearc basin.