“Neotectonics” in the northern African margin: new paleomagnetic constraints from northwestern Algeria

Abstract

20 Previous paleomagnetic studies performed in the central North-Algeria (Chellif and 21 Mitidja basins) on Neogene formations pointed out tectonic clockwise blocks rotations. This 22 deformation pattern was interpreted as resulting from a bookshelf neotectonics, consequence of 23 the Africa-Eurasia plates convergence. A new paleomagnetic study was conducted on the 24 Neogene volcanic rocks outcropping in the Northwestern Algeria (Marset Ben Mhidi -Aïn 25 Temouchent -Tifaraouine area). The obtained stable remanent magnetization is mainly carried 26 by Ti-poor titanomagnetite. The paleomagnetic data show that, since the lava emplacement, the 27 northwestern Algeria underwent a mean moderate clockwise block-rotations of 9.3° ± 4.5°. For 28 the Algerian margin, this confirms a context of transpression and blocks rotations in a strike-29 slip tectonic setting. A decreasing deformation gradient from the E to the W affected the 30 different basins of this margin, from strong rotations within the Mitidja, to the moderate ones 31 in the Chellif and to Marset Ben Mhidi -Aïn Temouchent -Tifaraouine area where rotations 32 magnitudes are significantly lower.