Paleogeographic Evolution of the Western Maghreb (Berberids) During the Jurassic

Serge Elmi

Several basins of the western Maghreb (northwest Africa) have been studied, taking into account their sedimentological and structural evolutions. Special attention is given to paleontological data (biostratigraphy, paleobiology, paleobiogeography).

The paleogeographic pattern was the result of the differentiation in four stable blocks (Moroccan Meseta, Oran High Plains, Constantine block, Tunisian north-south ridge) which were developed between the Sahara craton and median strike-slips of the Tethys. This area, called the Berberids, was split by basins and furrows evolving during the Jurassic. Large, shallow, heterochronous initial carbonate platforms (Early Jurassic) were broken by local tectonic movements (tilting and rifting). A mature progradation resulted from a rupture in the balance between carbonate production and subsidence. The result was the growth of more-or-less extended carbonate platforms along the basins' margins during the Aalenian and Bajocia. From the late Bajocian, a large deltaic system prograded from the so thwest and the west. Terrigenous input and large-scale tectonics provoked the filling of many basins. The southern and western areas became continental. In the north, carbonate series prograded on deltaic formations. A large, shallow platform developed on the southern rim of the Alpine Tethys. The tectonics of the basement became less important and sea level changes controlled the sedimentologic evolution.

Bio- and chronostratigraphic correlations allow us to chart the main tectonic and eustatic events which occurred in the western Maghreb during the Jurassic.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.