Constraint of Active Deformation between the African Platform and the Maghrebian Thrust Belt: Current Plate Motion from Permanent GNSS data in Algeria

The kinematic of tectonic motions between the African (Sahara) platform and the Maghrebian thrust belt remained unexplored since the onset of space geodesy. Here, we use data of 6 permanent GNSS stations located north and south of the Atlas thrust belt in Algeria to constrain shortening and transpression at the tectonic boundary. The permanent GPS data and results are obtained from the network in Algeria operative from 2013 to 2019, presented with the results of the REGAT network in Algeria since 2007. The south Atlas suture zone constitutes the limit between African (Sahara) shield domain considered as a stable continental interior and the Sahara Atlas that belong to the Alpine orogeny. The tectonic boundary is marked by a E-W to ENE-WSW, en echelon fold belt system with deformed Plio-Quaternary formations to the North and flat laying Mesozoic and Tertiary sedimentary units south of the suture zone. The GNSS data are processed using Gamit-GlobK and results show tectonic motions with a predominant 5 to 6 mm/yr velocities trending NNW-SSE to NW-SE (westward) in the Sahara Platform. The GPS velocities show uniform trend in the African platform from which we infer 0.5 to 1.0 mm/yr convergence across the south Atlas suture zone. The intraplate convergence is attested by the moderate but permanent seismic activity at the tectonic boundary.