Seismic Tomography Model for the Crust of Southern Crimea and Adjacent Northern Black Sea

This new seismic tomography study for the crust of southern Crimea and the northeastern Black Sea based on low-magnitude (M ≤ 3) earthquakes indicates significant heterogeneity of the crust at depths of 15–35 km. In the present paper we discuss the velocity distribution for P- and S-waves and give geological and tectonic interpretations in the context of collisional interaction between the Black Sea microplate and the Scythian plate. The joint use of data on both types of waves (P- and S-waves) increases the reliability of the interpretation and allows us to estimate the crustal composition of Mountainous Crimea (MC) and subcrustal mantle of the northeastern Black Sea. We have detected high velocity regions in the MC crust (Vp = 6.5‒6.8 km/s, Vs = 3.7‒3.9 km/s, Vp/Vs = 1.75‒1.9), which have complex configurations and can be deep sources of mid-Mesozoic intrusions known in the MC (Ayu-Dag and Castel). The high-velocity area is separated from eastern Crimea by a linear nearly north–south low-velocity zone located between the cities of Sudak and Feodosiya. The latter is interpreted as a weakened crustal zone associated with the Korsak–Feodosiya fault. The high-velocity region beneath the Black Sea (south of Kerch Peninsula) at depths of 25–40 km most likely belongs to the subcrustal mantle (Vp/Vs = 1.80–1.85) that underlies a thin suboceanic crust of the East Black Basin. The resulting crustal model for southern Crimea and adjacent part of the Black Sea is consistent with the parameters of other geophysical fields.