Transpressive tectonics along a major E–W crustal structure on the Algerian continental margin: Blocks rotations revealed by a paleomagnetic analysis

• Strong block rotations are revealed by paleomagnetism on northern Algerian margin.
• They are of Neogene age and localized along an E-W major dextral structure.
• Transpressional tectonic is related to the convergence Africa-Eurasia.

The present paleomagnetic study has been conducted on volcanic rocks of Miocene age outcropping on the northern border of the Neogene Chelif basin, northwest Algeria. The results show the existence of numerous small tectonic blocks, of probable size around 0.5 to 0.6 km, which underwent clockwise rotations. The magnitude of these rotations is often important and of different strengths according to the studied sites. That evidences the effect of a major narrow dextral E–W crustal shear structure. The location of this structure on the northern border of Chelif basin is coherent with the geodynamical context of this basin, which corresponds to a wide zone affected by clockwise rotations of large blocks limited by such major faults. The present paleomagnetic results confirm that the relative convergence motion between the Africa and Eurasia plates could be interpreted as a transpressional tectonic deformation model with block rotations along the Algerian continental margin.