Geodynamic evolution of north-east Algerian basin: 3D velocity model Reveals high-temperature flow

Abstract

By utilizing a two-station technique to extract Rayleigh wave phase velocity curves from 10 to 200 s of teleseismic events recorded by 12 broadband stations installed in northeastern Algeria, Tunisia, Sardinia, and Menorca island, we present a 3D shear wave velocity (Vs) model of the crust and upper mantle beneath the North-East Algerian Basin from 50 to 400 km depth. To estimate the 1D Vs-structures at each node of the two-station paths, which are each partitioned into 10 points, the extracted experimental Rayleigh wave phase velocity curves were inverted. According to the findings, there are two primary parallel high- and low-velocity bodies in the same region that are spreading in NE-SW direction. These bodies are largely located beneath the Algerian offshore in the north and extend to the Tell belt in Algeria with similar geometry. The high shear wave velocity body is at 200 and 350 km deep with Vs between 5 and 6 km/s, while the low-velocity body is at 50 and 100 km depth with Vs between 3 and 4 km/s. This opposition in velocity with similar geometry is explained by a high-temperature flow induced in the upper mantle caused by a subducting lithosphere of high-velocity penetration, which resulted in a concentrated low-velocity body between 50 and 100 km into the African mantle as a result of the convergence of the Africa-European plates. This high-velocity entity may be created by the oceanic lithosphere subducting.