A new lithostratigraphic nomenclatural framework is proposed for the Anti-Atlas Orogen of Morocco, to replace the previous
chronostratigraphic scheme. All the lithostratigraphic units of the Anti-Atlas Orogen are well represented in the Sirwa, Kerdous and
Sarhro inliers and examples from these areas are given prominence, though correlates in other areas are given, where known. The
oldest, Palaeoproterozoic, rocks of the cratonic basement form the northern part of the West African Craton and can be subdivided
into a series of Complexes (made up of constituent Groups, Suites etc.), depending on geographical outcrop (e.g. the Zenaga and
Kerdous Complexes in the Sirwa and Kerdous inliers respectively). The Neoproterozoic rocks deposited on this basement are termed
the Anti-Atlas Supergroup, within which five groups of volcano–sedimentary units (Taghdout, Jbel Lkst, Sarhro, Iriri, and Bou Azzer
Groups) and various intrusive igneous rocks are recognised (e.g. Ifzwane and Toudma Suites). These units are related to the earliest
passive margin, oceanic and island-arc development phases of the orogen between 800 and 660Ma. The earliest Pan-African deformation
(at 660Ma) resulted from closure of the ocean basin, SW-directed thrusting and accretion of the island-arc remnants. Continued
prolonged convergence gave rise to a sinistral transpressional regime in which late syn- to post-tectonic continental volcanic
and clastic sequences of the Ouarzazate Supergroup were deposited. The first rocks of this new tectonic regime were deposited in
narrow, tectonically active, strike-slip pull-apart rift basins (Bou Salda, Mgouna, Tafrawt and Anzi Groups) associated with intrusion
of high-K calc-alkaline granitoid batholiths (e.g. Assarag, Bardouz Suites) and the juxtaposition of ophiolitic remnants in major
strike-slip shear belts. These were followed by the deposition of the much more areally extensive continental volcano–sedimentary
molasse, the volcanic components of which were erupted from several interfingering volcanic centres, often associated with caldera
complexes and sub-volcanic alkaline granites (Toufhgrane, Tanghourt and Guellaba Suites). The proposed lithostratigraphic scheme
encompasses all the major rock units identified in the literature from the orogen and is flexible so that new, lower-ranking, units can
be placed at the appropriate stratigraphic level in future. This framework is supported by new high-precision U–Pb zircon dates that
have recently become available
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