Abstract

Precise biostratigraphic dating, weak tectonic deformation and perfect exposures have allowed detailed mapping of synchronous Givetian to Famennian facies belts in an area of about 23 000 km² in the eastern Anti-Atlas. Paleogeographical maps are presented of the following intervals: middle Givetian, late Givetian/early Frasnian, late Frasnian, early Famennian and late Famennian.

During Givetian a biostromal belt surrounding a depression in the west passed into a pelagic platform farther northeast. The following depositional areas can be distinguished during the Late Devonian (from W to E): Mader Platform, Mader Basin, Tafilalt Platform and Tafilalt Basin. The Mader Platform was largely emergent during Late Devonian and became totally submerged only in late Famennian. Up to 1500 m of shales, carbonates and sandstones accumulated in the Mader Basin. The depositional history of Middle and Late Devonian is best documented in the area of the pelagic Tafilalt Platform which crops out for 15-40 km in the W-E, and 80 km in the N-S directions. During the Middle and Late Devonian, this shallow pelagic ridge was covered by 5-50 m of cephalopod limestones which were deposited in increasing water depths from S to N. These pass laterally into shales and nodular limestones of the Tafilalt Basin. The biostratigraphically well established sequences terminate abruptly in latest Famennian (Strunian). The existing submarine topography was then levelled by thick deltaic deposits in the south which pass into turbidites towards the north.