Morpho-tectonic map of the Tyrrhenian back-arc basin

The Tyrrhenian back-arc basin is a Neogenic basin that opened in response to the E-SE-ward retreat of the subducting Ionian slab under the Apennine chain. To date a large bibliography is available for this basin (Moeller et al., 2014), but un updated morpho-structural map which takes into account the latest multibeam and multichannel seismic data sets is still lacking. Indeed, the structural maps of the entire Tyrrhenian date back to '80/'90. In this work, we present a new morpho-tectonic map of the entire Tyrrhenian basin, from slopes to abyssal plains. This map results from the analysis of 65 multichannel seismic profiles, several sparker profiles and 200-m-grid cell size bathymetry data. All data were georeferenced and interpreted together using the kingdom package (HIS Markit). In detail, the data sets used are composed by the: CROP profiles acquired in the '90; MS profiles acquired by the OGS during the '60/'80 (http://snap.ogs.trieste.it/); SITHERE profiles acquired for the site survey of IODP leg 107; MEDOC profiles acquired in 2010; and ISTEGE profiles acquired in the 2010. IODP/DSDP wells (Leg 107 and 42A) and crustal velocity information (Prada et al., 2014, 2015; 2018) were used for the seismo-stratigraphic calibration allowing the mapping of three main units: pre-Messinian; Messinian including evaporites; and Plio-Quaternary. This information allowed to constrain the age of faults activity.Our work results highlight a basin dominated by extension locally overprinted by compression or by transcurrent-motion fault systems. In the western Tyrrhenian, the extension was mostly accommodated by large listric faults forming deep and elongated sedimentary basins. In its eastern (Campania) and southern (Sicily-Calabria) margins the stretching was mainly accomplished through normal faults forming irregular and smaller basins. Furthermore, the central Magnaghi/Vavilov abyssal plain is confined by normal faults that bound the magmatic crust and exhumed mantle rocks (Prada et al., 2016) to continental blocks of the Sardinia-Campania conjugate margins. The Marsili abyssal plain instead is surrounded by fewer, not well expressed, normal faults and, to north and to south, by lithospheric faults (STEP fault).