Middle to Late Famennian successions at Ain Jemaa (Moroccan Meseta)—implications for regional correlation, event stratigraphy and synsedimentary tectonics of NW Gondwana

Abstract

AbstractTwo pelagic successions near Ain Jemaa (Oulmès region, Moroccan Meseta) are dated by conodonts and ammonoids and provide new data on the discontinuous Middle to Upper Famennian faunal and facies evolution in the region. Upper Devonian shales and nodular limestones are assigned to the new Bou Gzem Formation, which is subdivided into three members. The Upper Member consists of black shales that are correlated with the globally widespread, transgressive black shale interval of the Hangenberg Event. The overlying quartzites are interpreted as prodeltaic deposits and assigned to the new Táarraft Formation that probably correlate with the major regressive phase of the Hangenberg Event. Contemporaneous (‘Strunian’) coarse siliciclastics have a wide distribution in different structural units of the Meseta. Both studied sections display a long sedimentary gap but of different extent at the base of the black shales. Comparison with other regions of Hercynian Morocco suggest an influence of Eohercynian tectonics on sedimentation, leading to extreme condensation and/or non-deposition, whilst other Meseta areas show evidence of contemporaneous reworking on uplifted structural highs and massive shedding of mass flows, conglomerates and turbidites into adjacent pelagic basins. Data from Oulmés and other Meseta regions suggest a timing of tectophases as early Middle Famennian (starting within the marginifera Zone) and Upper Famennian (starting within the Middle expansa Zone), interrupted by transgressive pulses of the global Annulata and Dasberg Events.