Annali  di  Geofisica, VOL. 44, N. 5/6, October/December 2001

Paleomagnetism of the Liassic member of the Zerzaïtine formation (stable Saharan craton, Illizi basin, Algeria).

 Mohamed E.M. Derder (¹), Bernard Henry (²), Nacer Merabet (¹), Boualem Bayou (¹), Mohamed Amenna (¹).

(¹) CRRAG, Bouzaréah, Alger, Algeria

(²) Géomagnétisme et Paléomagnétisme, IPGP and CNRS, Saint Maur Cedex, France.

A paleomagnetic study was carried out in the carbonates and marls of the Liassic member of the Zarzaitine Formation of the Illizi basin (SE Algeria) deposited in a continental environnement. Two magnetization components were identified. The first, defined at relatively low blocking temperature, was isolated in five sites, and yields the following paleomagnetic pole (80.8°N, 20.10E, K = 811 and A₉₅ = 2.2°). This magnetization is considered an overprint acquired during Cenozoic times. The second component was defined by both normal and reversed polarity. The normal polarity was identified in fourteen sites using both linear regression and great circles. The reversed one was inferred in four sites from the remagnetization circle and demagnetization path analyses. This component is mainly (it could be in part the primary magnetization) a late diagenesis magnetic overprint. It yields a new Liassic pole (71.8°S, 54.9°E, K = 91 and A₉₅ = 3.9°) for Africa.

Key words : Africa - paleomagnetic pole - Liassic -apparent polar wander path - Sahara craaton