Physical properties of hard rocks collected in Tyrrhenian Basin during the IODP Expedition 402

The Tyrrhenian Sea is a young back-arc basin that has been shaped by various complex geologic processes, such as crustal thinning, mantle exhumation, and localized magmatism. For the last half-century, the basement of the Tyrrhenian basin was sampled during several ocean-drilling campaigns. The past expedition DSDP 42 and ODP107 revealed that that in addition to continental rocks of the passive margins, the Tyrrhenian basement also includes mafic rocks characteristic of an oceanic domain, and serpentinized peridotites indicative of exhumed mantle. In 2024, the IODP Expedition 402 returned to the Tyrrhenian Sea with the primary objective of sampling the transition between different tectonic domains in the Vavilov basin.

The basement rocks recovered during the IODP Expedition 402 ranged from felsic to ultramafic. Our results confirmed the continental affiliation of the conjugate Cornaglia and Campania terraces on the margins of the Vavilov basin. In the center of the basin, we recovered peridotites, mafic basalts and diorites, and granitoids in relatively close sites, revealing the apparent heterogeneity of the basement framework. In this paper, we summarize the physical properties of different basement lithologies of the Vavilov basin. We report average values of bulk density, porosity, grain density, compressional velocity, magnetic susceptibility, gamma-radiation, and thermal conductivity for different rock types. These parameters are crucial for geological, geophysical, geochemical, and geodynamic models of the study area, which will help to constrain the tectonic evolution of this complex geologic region.