The Atlas Mountains are classically regarded as a failed Mesozoic rift arm subject to Alpine inversion, folding and thrusting. Here, we present new integrated structural and sedimentological studies that have revealed numerous Early–Middle Jurassic diapiric ridges and minibasins, characterized by distinctive halokinetic structures. Diachroneity in halokinesis is observed across the Central High Atlas, waning first in the SW during the Early–Middle Jurassic (Jbel Azourki and Tazoult ridges) and continuing to late Middle Jurassic towards the NE (Imilchil region). The halokinetic structures are readily differentiated from the effects of later Alpine deformation, allowing a new picture of the Central High Atlas to emerge. The most pervasive deformation in the Central High Atlas is associated with Early–Middle Jurassic diapirism, whereas the impact of Alpine inversion is mostly focused at the basin margins. This new understanding helps explain previously problematic aspects of the Atlas Mountains, which we now recognize as an exceptionally well exposed natural laboratory for understanding the interactions between halokinesis, tectonics and sedimentation.

The central High Atlas (Morocco) constitutes a diapiric province that hosts a complex array of elongated diapirs and minibasins that formed during the Lower Jurassic rift of the Atlas Basin. This paper aims to study the structure and growth evolution of the Tazoult diapiric wall, located in the central High Atlas, by means of structural and sedimentological fieldwork integrated with remote sensing mapping. The Tazoult salt wall is a 20 km long × 3 km wide NE‐SW trending ridge that exposes Upper Triassic red beds and basalts along its core. The succession flanking the salt wall ranges from Hettangian to Bajocian ages displaying spectacular sedimentary wedges in the SE and NW flanks. The Hettangian‐early Sinemurian carbonates mainly crop out as blocks embedded in the core rocks. The ~1 km thick Pliensbachian platform carbonates display large subvertical flap structures along the flanks of the Tazoult salt wall with unconformities bounding tapered composite halokinetic sequences. In contrast, the ~2.5 km thick late Pliensbachian‐Aalenian mixed deposits form tabular composite halokinetic sequences displaying small‐scale hook halokinetic sequences. Passive diapirism resulted in the lateral extrusion of the evaporite‐bearing rocks to form an allochthonous salt sheet toward the adjacent SE Amezraï minibasin. The Bajocian platform carbonates partially fossilized the Tazoult salt wall and thus constitute a key horizon to constrain the timing of diapir growth and discriminate diapirism from Alpine shortening. The Pliensbachian carbonate platform evolved as a long flap structure during the early growth of the Tazoult salt wall, well before the onset of the Alpine shortening.

Subaerial exposure of carbonate platforms is generally recorded by karstification and pedogenesis, whereas erosion features such as incisions along emersion surfaces have seldom been observed and studied. However, the recognition of incisions and the characterization of their fill may facilitate definition and hierarchy of sequence boundaries, especially along exposure surfaces that do not otherwise present clear petrographic evidence for emersion. In the Natih Formation (Late Albian–Early Turonian, Oman), two successive incision surfaces are present in the upper part of the first third-order depositional sequence. Seismic interpretation of regional subsurface data has allowed the quantification of progradational geometries within the Natih sequence I carbonate platform and the correlation of incision surfaces with forced regressive prograding wedges on the margins of the intrashelf basin. Detailed geological sections and correlations have been made from three outcrop localities, allowing a precise description of geometries and facies of incision fills. Morphology, orientation, and extent of these incisions have been assessed from detailed seismic interpretation coupled with forward seismic modeling. The integration of outcrop and seismic data sets at the regional and local scales allows the interpretation and discussion of the origin and factors controlling the development of these incisions and a refinement of the stratigraphic model. These two incisions record rapid sea-level variations (500 ky) with a magnitude of approximately 20 and 30 m that occurred during the early Cenomanian. This is probably not a unique case, since for the same time interval, incisions have been observed in siliciclastic systems in western Canada and India and in carbonate systems on the Arabian plate.

The Natih Formation (late Albian–early Turonian, Oman) corresponds to a very broad inner carbonate platform extending over more than 800 km between the Arabian Shield to the south and the Tethys continental margin to the north. Two types of channelized systems have developed recurrently on this inner carbonate platform: incisions corresponding to strictly erosive drainage systems which formed at the top of the sub-aerially-exposed platform during significant drops of relative sea level; tidal channels corresponding to partly erosive but mainly constructive/depositional systems which formed during phases of flooding of the inner platform. The comparative analysis of the basal surface and fill of incisions and tidal channels, based on the study of several outcrops in the Oman Mountains allows the recognition of the similarities and the main differences between these two types of channelized systems which both develop in an inner carbonate platform setting. One of the main criteria of differentiation is the stratigraphic context in which incisions and channels develop. Incisions develop at the top of regressive sequences, whereas the channels analysed here developed during phases of flooding or maximum flooding, during which higher energy processes such as tidal currents developed on the platform. The incision surface is clearly defined, with diagenetic effects such as silicification and dolomitization below, and with the systematic fill of subjacent burrows and cracks by sparitic calcite crystals. The basal erosion surface of channels is often multiple and composite, systematically burrowed, and associated with no significant diagenetic effect. Channels are generally less deep than incisions but their width is very similar. Incisions are longer than channels and present a section that is, on the whole, symmetrical and regular, whereas channels locally have one margin that is steeper and more erosive than the other. Finally, the less diagnostic parameter of differentiation is their fill. Indeed, incisions and channels are similarly filled during phases of flooding of the inner platform. Incisions and channels form significant heterogeneities at the reservoir scale. It is therefore necessary to be able to recognize these two types of channelized systems, in order to predict their geometry, extent and fill type, and the eventual occurrence of associated reservoir bodies in the more distal direction (forced regressive wedges/bioclastic shoals).