The Devonian of Jebel Ben Arab (eastern part of Western Meseta) – review and new data

This study revises the Devonian lithostratigraphy of Jebel ben Arab in the eastern Western Meseta and shows that it formed a distinct sedimentary-tectonic unit, different from both the Azrou Devonian and the southern autochthonous successions. New conodont and microfacies data from southern and eastern sections allow a refined reconstruction of facies development and synsedimentary block movements. During the Lochkovian–Pragian, the Tchahbount Formation was deposited in an anoxic to hypoxic outer shelf basin, dominated by black and greenish shales and siltstones with few fossils. In the southern section, this passed upward into the Bouechot Formation, whose nodular griotte-like facies, dacryoconarids, erosional surfaces, and conodonts indicate a shallow pelagic setting influenced by contour currents. The eastern lower Emsian differs markedly, showing slumping, debris flows, laminated mudstones, and breccias that record an early synsedimentary tectonic phase and downslope deposition toward plant-bearing silty shales. More massive upper Emsian limestones contain pelagic faunas and are overlain by cyclic hypoxic shales and siltstones of the new Jebel Ben Arab Formation. At the top of its lower member, black shales mark the top-Eifelian Kačák Event, followed by a phosphoclastic float-rudstone that signals renewed Eovariscan seismic activity. The overlying middle Givetian succession consists of dark-grey turbiditic limestones with Bouma structures, reworked reef builders, and slump folds, indicating continued instability on a tectonically steepened lower ramp. A final major shift in the middle Givetian produced sandy and conglomeratic neritic deposits of the Mouzemmour Formation with reworked shallow-water fauna and abundant plant remains. These deposits suggest block uplift, subaerial exposure, vegetation development, and the formation of a mixed calcareous-siliciclastic shoreline before later isolated Famennian sedimentation.