Geological evolution and structural style of the Palaeozoic Tafilalt sub-basin, eastern Anti-Atlas (Morocco, North Africa)

The Tafilalt is one of a number of generally unexplored sub-basins in the eastern Anti-Atlas of Morocco, all of which probably underwent a similar tectono-stratigraphic evolution during the Palaeozoic Era. Analysis of over 1000km of 2-D seismic reflection profiles, with the interpretation of ten regional seismic sections and five isopach and isobath maps, suggests a multi-phase deformation history for the Palaeozoic-aged Tafilalt sub-basins. Extensional phases were probably initiated in the Cambrian, followed by uniform thermal subsidence up to at least the end of the Silurian. Major extension and subsidence did not begin prior to Middle[Upper Devonian times. Extensional movements on the major faults bounding the basin to the north and to the south took place in synchronisation with Upper Devonian sedimentation, which provides the thickest part of the sedimentary sequence in the basin. The onset of the compressional phase in Carboniferous times is indicated by reflectors in the Carboniferous sequence progressively onlapping onto the Upper Devonian sequence. This period of compression developed folds and faults in the Upper Palaeozoic-aged strata, producing a structural style characteristic of thin-skinned fold and thrust belts. The Late Palaeozoic units are detached over a regional decollement with a northward tectonic vergence. The folds have been formed by the process of fault-propagation folding related to the thrust imbricates that ramp up-section from the decollement. Copyright (C) 2007 John Wiley & Sons, Ltd.