A comprehensive lithospheric study of Black Sea using thermal modeling and simultaneous joint 3D inversion of potential field data

Abstract

We present a comprehensive lithospheric model of the Black Sea comprised of thermal structure, sediment thickness, and depths to Moho and lithosphere-asthenosphere boundary (LAB). The crustal structure (depths to Moho boundary and basement) is first estimated via a simultaneous joint 3D nonlinear inversion of satellite gravity data and the Gzz component of gravity gradiometry tensors. The results are then used for detailed 2D iterative forward modeling of potential field data based on the thermal structure of the lithosphere. In addition to potential field data, heat flow measurements are used for the iterative forward modeling. Eight 2D profiles across the Black Sea were selected to achieve a full coverage of the main geological structures. The average depth to basement is estimated as 10–11 km in the East Black Sea (EBS) basin and 11–12 km in the West Black Sea (WBS) basin. The average depth to basement beneath the ridges is estimated between 2 and 5 km. The modeling results show a mean thickness of 20 km and 21 km for the crust and 150 and 100 km for the lithosphere in the central parts of EBS and WBS, respectively. While the lithosphere is thicker in the EBS than in the WBS, a LAB uplift in the central basins is obvious in the reconstructed model. Also, the calculated surface heat flow is highest at the ridges while the lowest values are found over thick sediments in the central basins. After correcting the calculated heat flow data for the sedimentation effect, the resulting values match the published measurements indicating the reliability of the obtained thermal structure for the Black Sea.