Middle to Late Famennian successions at Ain Jemaa (Moroccan Meseta)—implications for regional correlation, event stratigraphy and synsedimentary tectonics of NW Gondwana
Published:January 01, 2007
S. I. Kaiser, R. T. Becker, A. El Hassani, 2007. "Middle to Late Famennian successions at Ain Jemaa (Moroccan Meseta)—implications for regional correlation, event stratigraphy and synsedimentary tectonics of NW Gondwana", Devonian Events and Correlations, R. T. Becker, W. T. Kirchgasser
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Two 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.
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Devonian Events and Correlations
The Devonian was a peculiar period, characterized by simplified plate tectonic configurations, climatic overheating and widely flooded continents. The bloom of fishes and ammonoids, extensive reef complexes, and the conquest of land indicate major biosphere innovations, punctuated by many global events, including two of the biggest mass extinctions. The Devonian was the first system for which subdivisions were formally defined. This was achieved by significant advances in pelagic biostratigraphy. The chronostratigraphic framework and interdisciplinary techniques allow us to correlate intervals or sudden events across facies boundaries, in order to reconstruct the sedimentary and evolutionary history of the system with highest precision.
This volume honors the lifetime stratigraphic achievements of Michael Robert House (1930-2002). Based on case studies from Europe, North Africa and North America, it shows how the combination of biostratigraphy, chemostratigraphy, magnetostratigraphy, sequence stratigraphy and event stratigraphy can contribute to a much deeper understanding of both regional and global environmental change.