THE PERMIAN-TRIASSIC TRANSITION AND THE BEGINNING OF THEMESOZOIC SEDIMENTATION OF HIGH ATLAS OF MARRAKECH ANDARGANA BASINS: ATTEMPT OF CORRELATION AT WESTERN PERITETHYANDOMAIN

International audienceThe Permian-Triassic Boundary is an important interval, intensely studied to clarify climatic, biotic andenvironmental conditions. Continental sedimentation of the studied interval, upper F2/F3/lower F4 and upperT2/T3/lower T4 units, respectively in the High Atlas of Marrakech and Argana Valley spans from late Permian,dated from vertebrates, to Middle Triassic. It records all changes in the depositional environments undertectonic and climatic control. The sedimentological study aimed to characterize the Permian-Triassic transitionby a sedimentological outcrop analysis, to recognize sedimentary facies, facies associations, to reconstitute thedepositional history and the palaeogeography evolution from the end of the Permian to the beginning of theTriassic siliciclastic succession. Finally, from depositional sequences we propose stratigraphic correlation atthe scale of Morocco basins and the western Peri-Tethyan domain. The late Permian (upper F2/upper T2 units)facies association represents fluvial fans in a dry alluvial plain. The Early Triassic F3 /T3, dated from foodprints, and F4a/T4a units rest unconformably on the Permian strata, and consist of (i) arid alluvial fans, (ii)aeolian deposits, (iii) palustrine-lacustrine deposits, (iv) floodplain, (v) meandering river and (vi) braided river.The Anisian F4b/T4b units represent axial fluvial plain of high sinuosity rivers. The dynamics of alluvial fan,fluvio-lacustrine, eolian deposits, the synsedimentary tectonic and the baselevel fluctuations will be taken intoconsideration during the filling of the sedimentary basins to constrain the stratigraphic cycles. The evolutionof early Triassic environments constitutes a major stratigraphic cycle with retrogradational and progradationaltrends, and is bounded by surfaces correlated at the scale of Morocco basins. The Anisian units arecharacterized by floodplain and meandering river deposits, and represent the beginning of another stratigraphiccycle. The stratigraphic cycle can be discussed at the scale of western Peri-Tethyan domai