MAGNETOSTRATIGRAPHY OF NEOGENE SERIES OF THE GUERCIF BASIN (MOROCCO)

This paper presents the results of paleomagnetic investigations on continental and marine Neogene deposits in the Guercif basin in northeastern Morocco. The Guercif basin is the eastern continuation of the Neogene foredeep of the Moroccan Rif Mountains, from which it has been separated by the late Neogene uplift of the Middle Atlas Mountain. Four stratigraphic sections have been analyzed on which 136 samples have been taken for the magnetostratigraphy study. The magnetic characteristics of these rocks show that the magnetization usually results from the presence of magnetite, titano-magnetite, goethite and hematite. The results demonstrate the presence of a single reverse polarity in the case of the Khendek El Ouaich section correlated with chron C3Br.2r (similar to 7.3 - 7.5 Ma). Magnetostratigraphic investigations in Safsafate section in the Messinian deposits show that it could be correlated with chrons C3Br.1n - C3Ar (similar to 6.7 - 7.3 Ma). The Ain Guettara and Oued Lahmar sections show a succession of at least seven polarities that are correlated with chrons C3n.4n - C3n.2n (similar to 4.5 - 6.0 Ma). These results along with new biostratigraphic studies based on rodent faunas and volcanism permit to establish the age of tectonic activity and deposition.