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The Central High Atlas of Morocco is the result of the Alpine tectonic inversion of an intracontinental Mesozoic basin, the infill of which started with thick Upper Triassic clay and evaporite deposition. This slightly deformed mountain range is characterized by narrow ENE-WSW ridges that expose a Triassic core. These ridges bound unique synclines filled by thick Jurassic successions showing well-preserved halokinetic depositional sequences, interpreted as salt-related minibasins. This paper aims to describe and analyze the evolution of diapiric movements and their interactions with Lower and Middle Jurassic carbonate dominated sedimentation in the Imilchil area, which corresponds to the axial part of the Atlas basin. Four diapiric ridges have been identified in this region: the Tasraft, Tassent, Ikkou, and Amagmag, which expose Triassic shales and are intruded by Triassic and Jurassic magmatic rocks. These ridges delineate three minibasins: Ikassene, Lakes (Lake Plateau), and Tilmi (Ikkou), each 5 to 10 km wide, preserving over 6,000 m of Upper Liassic and Dogger deposits. The Atlas basin is filled with five third-order transgression-regression cycles organized as one regressive megasequence. This long regressive trend is expressed by the succession of three depositional systems: i) a distal to proximal carbonate ramp system from the Toarcian to Late Bajocian; ii) a shallow mixed carbonate-siliciclastic system from the Late Bajocian to Early Bathonian; and iii) a fluvial system from the Bathonian to Early Callovian. Throughout this period, the development of coeval diapiric ridges significantly influenced these sedimentary systems, though the intensity of the diapiric activity varied over time. During the Late Bajocian, ridge growth slowed considerably amid the peak progradation of the carbonate systems. It then increased significantly from the latest Bajocian onward, due to a drastic rise in siliciclastic flux and sedimentation rate in the Atlas basin. The effects of diapirism on sedimentation are observed regionally (several kilometers), as minibasins evolve as depocenters, each exhibiting distinct subsidence rates and sedimentary thicknesses. Despite these local variations, the regional scale paleogeography and the sequential organization of the deposits remained largely unaffected. On a smaller scale (hectometers to kilometers), diapiric structures are always characterized by halokinetic depositional patterns. Internal angular unconformities only occur in very shallow-marine to continental deposits during periods of maximum ridge growth and subaerial exposure (notably in the Bathonian). At this scale, diapiric movements lead to local facies variations within shallow-marine deposits, fostering the development of bioconstructed or grainy carbonate sediment bodies along the ridges. However, in outer ramp environments, the submarine topographies created by ridge growth were generally insufficient to induce similar facies variations.

The Mauléon Basin, in the northwestern Pyrenean Belt, is related to Early Cretaceous rifting and mantle denudation. Here we review the evolution of depositional systems in the Mauléon Rift Basin during Albian and Cenomanian time. This review includes the lithostratigraphy, regional distribution, boundaries, age and facies sedimentology of the basin’s syn-rift formations and their members. We construct paleogeographic maps to elucidate (1) the 3D distribution of sedimentary facies and depositional systems during the Albian and Cenomanian from the Iberian proximal margin to the hyperextended domain and (2) the link between major extensional structures and sedimentation during rifting and mantle denudation. The Mauléon Rift was supplied during most of the Albian by sediments from the Iberian proximal margin. The southern margin had a steep and abrupt topographic boundary related to a northward crustal rollover along the south-dipping Saint-Palais detachment. This feature controlled the deposition of coarse-grained turbidites at the base of the margin that abruptly gave way to low-density turbidites, then deep-basin deposits in the hyperextended domain. During uppermost Albian to Early Cenomanian time, mantle denudation occurred in the eastern Mauléon Basin and the vergence of the detachment systems reversed. Minor debris-flow deposits formed at the foot of fault scarps associated with the newly formed north-dipping detachments. Elsewhere, sediment from deltaic systems to the west in the Saint-Jean-de-Luz area deposited low-density turbidites in the hyperextended domain. During the post-rift stage, the flux of coarse sediment from the detachment footwall gradually declined as deformation waned, and low-density turbidites expanded onto the hyperextended domain from the European Upper Cretaceous carbonate platform. These paleogeographic reconstructions, in addition to offering a synthetic view of the evolution of sedimentary environments during rifting, offer new insight into the post-rifting exhumation of the lower crust and mantle. Le bassin de Mauléon, localisé dans les Pyrénées nord-occidentales, subit une phase de rifting aboutissant à la dénudation du manteau au cours du Crétacé inférieur. Dans ce travail, nous synthétisons l’évolution des systèmes de dépôts Albien à Cénomanien du bassin de Mauléon. Cette synthèse inclut les lithologies, la répartition régionale, les limites stratigraphiques, les âges et les faciès des différentes formations et membres syn-rifts du bassin de Mauléon. Ces derniers ont été temporellement et spatialement corrélés afin de reconstruire des cartes paléogéographiques offrant une meilleure compréhension: (1) de la distribution 3D des faciès sédimentaires et des systèmes de dépôts de l’Albien au Cénomanien entre la marge proximale ibérique et le domaine hyper-aminci du bassin de Mauléon et (2) du lien entre les principales structures extensives et la sédimentation au cours du rifting et de la dénudation du manteau. De l’Albien inférieur à supérieur, le bassin de Mauléon était essentiellement alimenté depuis la marge proximale ibérique. La forte pente topographique de cette marge, est due à un basculement vers le nord provoqué par le détachement à vergence sud de Saint-Palais. Cette géométrie a favorisé des dépôts de conglomérats de bassin profond au pied de la marge ibérique passant de manière brutale à des faciès hémipélagiques du domaine hyper-aminci. De l’Albien terminal au Cénomanien inférieur, la vergence des systèmes de détachements s’inverse. Cette étape finale de structuration du bassin conduit à la dénudation du manteau dans la partie orientale du bassin. Des debris flows mineurs, issus de l’érosion sous-marine du mur des détachements à vergence nord, sédimentent au pied des escarpements de failles. À la même époque, les turbidites de faible densité, se déposent dans le domaine hyper-aminci, alimentées par un système deltaïque de polarité Ouest-Est provenant du domaine occidental de Saint-Jean-de-Luz. Au cours du stade postrift, les flux sédimentaires grossiers provenant des escarpements des détachements diminuent corrélativement avec la diminution du jeu tectonique sur ces accidents tandis que les turbidites de faible densité se déposent dans le domaine hyper-aminci proviennent de la plateforme carbonatée européenne. En plus d’offrir une vision synthétique de l’évolution des milieux sédimentaires lors du rifting, ces reconstructions paléogéographiques apportent de nouvelles réflexions quant à l’évaluation de l’exhumation de la croûte inférieure et du manteau.

Continental rifts and passive continental margins show fundamental along‐axis segmentation patterns that have been attributed to one or a number of different processes: extensional fault geometry, variable stretching along strike, preexisting lithospheric compositional and structural heterogeneities, oblique rifting, and the presence or absence of eruptive volcanic centers. The length and width scales of the rift stage fault‐bounded basin systems change during the late evolution of the new plate boundary, and the role of magmatism may increase as rifting progresses to continental rupture. Along obliquely spreading ridges, first‐order mid‐ocean ridge geometries originate during the synrift stage, indicating an intimate relationship between magma production and transform fault spacing and location. The Gulf of Aden rift is a young ocean basin in which the earliest synrift to breakup structures are well exposed onshore and covered by thin sediment layers offshore. This obliquely spreading rift is considered magma‐poor and has several large‐offset transforms that originated during late stage rifting and control the first‐order axial segmentation of the spreading ridge. Widely spaced geophysical transects of passive margins that produce only isolated 2‐D images of crust and uppermost mantle structure are inadequate for evaluation of competing rift evolution models. Using closely spaced new geophysical and geological observations from the Gulf of Aden we show that rift sectors between transforms have a large internal variability over short distances (∼10 km): the ocean‐continent transition (OCT) evolves from a narrow magmatic transition to wider zones where continental mantle is probably exhumed. We suggest that this small‐scale variability may be explained (1) by the distribution of volcanism and (2) by the along‐strike differences in time‐averaged extension rate of the oblique rift system. The volcanism may be associated with (1) the long‐offset Alula‐Fartak Fracture Zone, which may enhance magma production on its younger side, or (2) channeled flow from the Afar plume material along the newly formed OCT and the spreading ridge. Oblique extension and/or hot spot interactions may thereby have a significant control on the styles of rifting and continental breakup and on the evolution of many magma‐poor margins.

The Central High Atlas of Morocco is the result of the Alpine tectonic inversion of an intracontinental Mesozoic basin, the infill of which started with thick Upper Triassic clay and evaporite deposition. This slightly deformed mountain range is characterized by narrow ENE-WSW ridges that expose a Triassic core. These ridges bound unique synclines filled by thick Jurassic successions showing well-preserved halokinetic depositional sequences, interpreted as salt-related minibasins. This paper aims to describe and analyze the evolution of diapiric movements and their interactions with Lower and Middle Jurassic carbonate dominated sedimentation in the Imilchil area, which corresponds to the axial part of the Atlas basin. Four diapiric ridges have been identified in this region: the Tasraft, Tassent, Ikkou, and Amagmag, which expose Triassic shales and are intruded by Triassic and Jurassic magmatic rocks. These ridges delineate three minibasins: Ikassene, Lakes (Lake Plateau), and Tilmi (Ikkou), each 5 to 10 km wide, preserving over 6,000 m of Upper Liassic and Dogger deposits. The Atlas basin is filled with five third-order transgression-regression cycles organized as one regressive megasequence. This long regressive trend is expressed by the succession of three depositional systems: i) a distal to proximal carbonate ramp system from the Toarcian to Late Bajocian; ii) a shallow mixed carbonate-siliciclastic system from the Late Bajocian to Early Bathonian; and iii) a fluvial system from the Bathonian to Early Callovian. Throughout this period, the development of coeval diapiric ridges significantly influenced these sedimentary systems, though the intensity of the diapiric activity varied over time. During the Late Bajocian, ridge growth slowed considerably amid the peak progradation of the carbonate systems. It then increased significantly from the latest Bajocian onward, due to a drastic rise in siliciclastic flux and sedimentation rate in the Atlas basin. The effects of diapirism on sedimentation are observed regionally (several kilometers), as minibasins evolve as depocenters, each exhibiting distinct subsidence rates and sedimentary thicknesses. Despite these local variations, the regional scale paleogeography and the sequential organization of the deposits remained largely unaffected. On a smaller scale (hectometers to kilometers), diapiric structures are always characterized by halokinetic depositional patterns. Internal angular unconformities only occur in very shallow-marine to continental deposits during periods of maximum ridge growth and subaerial exposure (notably in the Bathonian). At this scale, diapiric movements lead to local facies variations within shallowmarine deposits, fostering the development of bioconstructed or grainy carbonate sediment bodies along the ridges. However, in outer ramp environments, the submarine topographies created by ridge growth were generally insufficient to induce similar facies variations.

Here, the larger foraminifera found in Middle Eocene-Early Miocene rocks from Dhofar (Oman) and Socotra Island (Yemen) are studied in detail. The architectural analysis leads to the description of five new genera and nine new species: five agglutinated foraminifera, Pseudolituonella robineti n. sp., Socotraella ashawqi n. gen. n. sp., Pseudoaccordiella ayaki n. gen. n. sp., Barattolites andhuri n. sp., and Rogerella aydimi n. gen. n. sp.; and four porcellaneous foraminifera, Idalina grelaudae n. sp., Idalina pignattii n. sp., Macetadiscus incolumnatus n. gen. n. sp., and Omanodiscus tenuissimus n. gen. n. sp. The larger foraminifera identified in a composite section located in western Dhofar, in the Shuwaymiyah section located in eastern Dhofar, and in the Wadi Ayak section located on Socotra Island have facilitated the identification of the following larger foraminifera zones: SBZ 14–SBZ 15 (middle Lutetian), SBZ 16 (late Lutetian), SBZ 17 (Bartonian), SBZ 18 (latest Bartonian-earliest Priabonian), SBZ 19–SBZ 20 (Priabonian), SB 21–SB 22A (Rupelian), SB 22B–SB 23 (Chattian), and SB 24 (Aquitanian). All these data permit to assess the age of the following lithostratigraphic units: Dammam Fm.—Andhur Mb. lower Lutetian?-middle Lutetian age (SBZ 13?–SBZ 14 partim), Qara Mb. middle Lutetian (SBZ 14–SBZ 15), and Uyun Mb. upper Lutetian (SBZ 16); Aydim Fm.—Heiron Mb. Bartonian (SBZ 17), Moosak Mb. upper Bartonian-Priabonian (SBZ 18–SBZ 20), Tagut Mb. Priabonian (SBZ 19–SBZ 20), and Haluf Mb. Priabonian (SBZ 19–SBZ 20) to lower Rupelian (SBZ 21) on Socotra Island; Ashawq Fm. Rupelian (SB 21–SB 22A); and Mughsayl Fm. Chattian-Aquitanian (SB 23–SB 24).