Extensional tectonics during the Tyrrhenian back‐arc basin formation and a new morpho‐tectonic map

Abstract

We present a new tectonic map focused upon the extensional style accompanying the formation of the Tyrrhenian back‐arc basin. Our basin‐wide analysis synthetizes the interpretation of vintage multichannel and single‐channel seismic profiles, integrated with modern seismic images, P‐wave velocity models, and high‐resolution morpho‐bathymetric data. Four distinct evolutionary phases of the Tyrrhenian back‐arc basin opening are further constrained, redefining the initial opening to Langhian/Serravallian time. Listric and planar normal faults and their conjugates bound a series of horst and graben, half‐graben and triangular basins. Distribution of extensional faults, active throughout the basin since Middle Miocene, allows us to define an arrangement of faults in the northern/central Tyrrhenian mainly related to a pure shear which evolved to a simple shear opening. At depth, faults accommodate over a Ductile‐Brittle Transitional zone cut by a low‐angle detachment fault. In the southern Tyrrhenian, normal, inverse and transcurrent faults appear to be related to a large shear zone located along the continental margin of the northern Sicily. Extensional style variation throughout the back‐arc basin combined with wide‐angle seismic velocity models allows to explore the relationships between shallow deformation, faults distribution throughout the basin, and crustal‐scale processes as thinning and exhumation.

Surface‐Wave Tomography of the Central‐Western Mediterranean: New Insights Into the Liguro‐Provençal and Tyrrhenian Basins

“…We speculate that this portion of the basin was not affected by as prominent a mantle flow as the rest of the Tyrrhenian basin, because it was formed before the rapid extension due to the Ionian slab break‐off (i.e., before the Pliocene phase described in Loreto et al. (2021)).…”

“…In recent times, an effort has been made to reconcile active seismic observations with those collected in ocean drilling surveys, that resulted in a detailed tectonic map of the Tyrrhenian Sea and in a new kinematic model for the opening of the basin (see Loreto et al., 2021, and references therein). According to Loreto et al.…”

Evolution of the Alpine orogenic belts in the Western Mediterranean region as resolved by the kinematics of the Europe-Africa diffuse plate boundary

“…At ~30 Ma, slab rollback-related extension in the Western Mediterranean opens the Gulf of Lion and Valencia basins, followed by extension in the and Tyrrhenian basins (~15 Ma) (Fig. 2; Comas et al 1992Comas et al , 1996Lonergan and White, 1997;Jolivet et al, 1999;Séranne, 1999;Loreto et al, 2020).…”

An Integrated Multiscale Method for the Characterisation of Active Faults in Offshore Areas. The Case of Sant’Eufemia Gulf (Offshore Calabria, Italy)

“…Among the geophysical methodologies used to detect active faults, the high-resolution seismic reflection imaging provides a powerful tool to unravel the Late Quaternary activity of faults, to measure the displacements along the fault planes and to correlate the onshore with the offshore segments (e.g., Barreca et al, 2014;Barreca et al, 2018;Ferranti et al, 2014;Cultrera et al, 2017a;Corradino et al, 2021). Standard methods for qualitative morphotectonic analysis that use multibeam high-resolution bathymetric data consist of tracing in plan-view the faults that offset the seafloor and in recognising morphological features close to the tectonic structures, such as rectilinear canyons, scarps or seafloor undulations (e.g., Fracassi et al, 2008;Di Bucci et al, 2009;Loreto et al, 2013;Cultrera et al, 2017b;Loreto et al, 2021). However, a limitation in reconstructing complex structural pattern in offshore areas is caused by the difficulty in mapping faults in areas not fully covered by geophysical data, by the low preservation potential of fault scarps and, often, by the blind nature of the tectonic deformation occurring when the structures do not produce detectable deformation at shallow depth (due to their geometry and depth).…”