Dinosaur footprints and other Ichnofauna from the Cretaceous Kem Kem Beds of Morocco

We describe an extensive ichnofossil assemblage from the likely Cenomanian-age 'lower' and 'upper' units of the 'Kem Kem beds' in southeastern Morocco. In the lower unit, trace fossils include narrow vertical burrows in cross-bedded sandstones and borings in dinosaur bone, with the latter identified as the insect ichnotaxon Cubiculum ornatus. In the upper unit, several horizons preserve abundant footprints from theropod dinosaurs. Sauropod and ornithischian footprints are much rarer, similar to the record for fossil bone and teeth in the Kem Kem assemblage. The upper unit also preserves a variety of invertebrate traces including Conichnus (the resting trace of a sea-anemone), Scolicia (a gastropod trace), Beaconites (a probable annelid burrow), and subvertical burrows likely created by crabs for residence and detrital feeding on a tidal flat. The ichnofossil assemblage from the Upper Cretaceous Kem Kem beds contributes evidence for a transition from predominantly terrestrial to marine deposition. Body fossil and ichnofossil records together provide a detailed view of faunal diversity and local conditions within a fluvial and deltaic depositional setting on the northwestern coast of Africa toward the end of the Cretaceous

Reply to comment by El Ouardi et al. on The Cu–Pb–Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution

This note is a reply to the « Comment on The Cu-Pb-Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution » by Hmidou El Ouardi et al., published in Comptes Rendus Géoscience in Volume 354, 2022, pages 119–123 (https://doi.org/10.5802/crgeos.115). It concerns the article « The Cu-Pb-Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution » by Aabi et al., published online on May 04, 2021, in Comptes Rendus Geoscience in Volume 353, 2021, pages 81–99 (https://doi.org/10.5802/crgeos.54)

The Cu–Pb–Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution

In the central Saghro massif of the Moroccan Anti-Atlas belt, the Bou Skour polymetallic deposit is hosted within mafic to felsic rocks of the Ediacaran Saghro Group and the lower Ouarzazate Group together with Pan-African plutons and dykes. The mineralizations occur in a brittle-ductile shear zone as a vein-type system recently dated at $574.9 \pm 2.4~\mathrm{Ma}$. In this contribution, a new multi-scale structural mapping and vein system analysis have been integrated to understand structural control and tectonic evolution of the Bou Skour deposit. The most important mineralized structures are known as “Filon Principal”, “Filon 1”, and “Filon 2” and are mainly hosted within NNW to NW transcrustal faults. They are represented as en-echelon tension gashes occasionally associated with horsetail satellite structures pointing to left-lateral strike-slip movement. The age and tectonic patterns are coherent with the NW–SE shortening of the last stage of the Pan-African orogeny rather than with post Pan-African events. Subsequent collapses and tilted blocks were accommodated by NE- to ENE normal and strike-slip faults in response to the Late Ediacaran–Cambrian extension events. Much later, probably during the Variscan or even Atlasic shortening, conjugated strike-slip reverse faults and related folds occurred, disrupting most of the rhyolitic dykes as well as the major mineralized structures

The Cu–Pb–Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution

In the central Saghro massif of the Moroccan Anti-Atlas belt, the Bou Skour polymetallic deposit is hosted within mafic to felsic rocks of the Ediacaran Saghro Group and the lower Ouarzazate Group together with Pan-African plutons and dykes. The mineralizations occur in a brittle-ductile shear zone as a vein-type system recently dated at $574.9 \pm 2.4~\mathrm{Ma}$. In this contribution, a new multi-scale structural mapping and vein system analysis have been integrated to understand structural control and tectonic evolution of the Bou Skour deposit. The most important mineralized structures are known as “Filon Principal”, “Filon 1”, and “Filon 2” and are mainly hosted within NNW to NW transcrustal faults. They are represented as en-echelon tension gashes occasionally associated with horsetail satellite structures pointing to left-lateral strike-slip movement. The age and tectonic patterns are coherent with the NW–SE shortening of the last stage of the Pan-African orogeny rather than with post Pan-African events. Subsequent collapses and tilted blocks were accommodated by NE- to ENE normal and strike-slip faults in response to the Late Ediacaran–Cambrian extension events. Much later, probably during the Variscan or even Atlasic shortening, conjugated strike-slip reverse faults and related folds occurred, disrupting most of the rhyolitic dykes as well as the major mineralized structures

A New Pterosaur (Pterodactyloidea: Azhdarchidae) from the Upper Cretaceous of Morocco

The Kem Kem beds in South Eastern Morocco contain a rich early Upper (or possibly late Lower) Cretaceous vertebrate assemblage. Fragmentary remains, predominantly teeth and jaw tips, represent several kinds of pterosaur although only one species, the ornithocheirid Coloborhynchus moroccensis, has been named. Here, we describe a new azhdarchid pterosaur, Alanqa saharica nov. gen. nov. sp., based on an almost complete well preserved mandibular symphysis from Aferdou N'Chaft. We assign additional fragmentary jaw remains, some of which have been tentatively identified as azhdarchid and pteranodontid, to this new taxon which is distinguished from other azhdarchids by a remarkably straight, elongate, lance-shaped mandibular symphysis that bears a pronounced dorsal eminence near the posterior end of its dorsal (occlusal) surface. Most remains, including the holotype, represent individuals of approximately three to four meters in wingspan, but a fragment of a large cervical vertebra, that probably also belongs to A. saharica, suggests that wingspans of six meters were achieved in this species. The Kem Kem beds have yielded the most diverse pterosaur assemblage yet reported from Africa and provide the first clear evidence for the presence of azhdarchids in Gondwana at the start of the Late Cretaceous. This, the relatively large size achieved by Alanqa, and the additional evidence of variable jaw morphology in azhdarchids provided by this taxon, indicates a longer and more complex history for this clade than previously suspected

The Atlas-Meseta Red Beds basin (Morocco) and the Lower Ordovician rifting of NW-Gondwana

The transition from the Cambrian to Ordovician in Morocco is known to be characterized by a frequent Furongian hiatus, restricted extension of the Tremadocian marine deposits, and frequent unconformities at the base of the transgressive upper Floian deposits. In the present work, we first highlight the occurrence of Fe- and mica-rich, red silty/sandy formations in the Central and Eastern High Atlas between the Middle Cambrian and Upper Floian sequences. In the Tislyt type-locality, a synsedimentary hemigraben structure is defined, within which the red beds show frequent slump folds, debris flows and internal unconformities. The correlation with several coeval series of the Meseta domain allows us to define a shallow marine, ferruginous clastic Atlas-Meseta Red Beds (AMRB) basin during the Tremadocian-early Floian. The AMRB basin extended between the Meseta coastal block and the Anti-Atlas domain, being limited by the fault zones that became the West Meseta shear zone and the South Meseta fault, respectively, in the Variscan orogen. The AMRB basin compares with the coeval rifted basins of the central Iberian and Armorican massifs. The red beds were likely sourced from the east, from both the Precambrian basement and Early Ordovician magmatic rocks, contrary to the Ordovician deposits of the Sahara platform sourced from the south. Subsidence of the AMRB and central Iberian-Armorican basins of the NW-Gondwana border aborted during the Floian, whereas the opening of the Rheic ocean went on more to the west