The lithospheric structure underneath the Circum Black Sea: Teleseismic receiver functions and Rayleigh wave phase velocity analysis

Abstract

• Lithospheric structure beneath Circum Black Sea is revealed using joint inversion. • Moho depth increases southward from 35 to 40 km along Black Sea coastline. • Lithospheric depth increases southward beneath east of Black Sea (90–130 km). In this paper, the lithospheric structure underneath the Circum Black Sea is investigated on the basis of teleseismic receiver functions and Rayleigh wave phase velocity analyses. A joint inversion of P- and S-wave receiver functions are performed by using an iterative algorithm, similar to the simulated annealing method. The array method is employed to obtain the Rayleigh wave inter-station phase velocity dispersion curves. The dataset recorded during 2010–2020 by sixteen broadband stations, operated by several seismological agencies, includes more than 450 events (Mw ≥ 5.8). The Moho depth increases northward from 35 km to 40 km along both coastlines. Following the velocity models, it is suggested that the crust structure beneath the stations is the continental type. The lithosphere-asthenosphere boundary ranges from ~ 90 km to ~ 120 km from the east coast of the East Black Sea basin, while it is low-sloping (from ~ 100 km to ~ 93 km) for the west coast of the West Black Sea basin, and it is nearly 90 km along with the Pontides. The average P-wave and S-wave velocities inferred from the models indicate the continental lithosphere around the Black Sea coastal region. According to these results, tectonically, it points out that the southward subduction exists in the eastern part of the East Black Sea region beneath the Pontides, while it is not observed in the westernmost Black Sea region.