Integrated Geophysical Modeling of Tectonic and Crustal Structures across the Tyrrhenian Sea

The Tyrrhenian Sea, a Neogene back-arc basin in the central Mediterranean, is a site of active debate regarding its crustal affiliation as both oceanic basalts and gabbroic rocks, as well as exhumed mantle peridotites were recovered throughout the Tyrrhenian Sea. Interestingly, the recent IODP Expedition 402 revealed granitoids and serpentinized peridotites in close proximity drill sites within the Vavilov basin. These apparent heterogeneous mantle rocks warrant further research using an integrated geophysical approach, incorporating all available geophysical data to understand the spatial distribution of crustal domains across the Tyrrhenian seafloor.

The crustal heterogeneity in the study area results from the interplay of back-arc extension processes, including localized mantle exhumation, crustal thinning, and magmatic intrusions driven by the eastward retreat of the Calabrian-Apennine subduction system. This study investigates the tectonic affinity of the crust in the region via joint analysis of published seismic reflection and refraction data from MEDiterraneo OCcidental (MEDOC) 4 and 6 surveys, topography data, and potential fields (gravity and magnetic). Drilling results from DSDP 373, ODP Leg 107 and IODP Exp. 402 served as geological constraints for geophysical interpretations.

We present two 2D subsurface models along the MEDOC-4 and MEDOC-6 profiles that reveal the geometry of crustal and mantle structures and explain variations in the observed gravity and magnetic anomalies through differences in their physical properties. The models highlight the variations in densities and magnetic susceptibilities in all prominent geologic structures that profiles transect, including the Baronie, Magnaghi, Vavilov, and Flavio Gioia Seamounts. We also present a map delineating the spatial distribution of rock types in the central Tyrrhenian Sea, which outlines continental, oceanic and exhumed mantle domains using all data blended in the analysis.