The Eocene Bryozoans of Bekrit-Timahdite Formation, Middle-Atlas, Morocco: Taxonomy, Paleoenvironments and Paleoclimates Implications

Abstract

Located in the NorthWest of the African continent, the Moroccan Middle Atlas constitutes an intra-continental chain within the Atlas domain. It is known by several global geological events such as the Paleocene-Eocene crisis during the Paleogene, which corresponds to one of the hottest periods on earth with Paleocene-Eocene thermal maximum (PETM). A taxonomic study carried out on the carbonate deposits of the Bekrit-Timahdite Formation from three sections of the Bekrit syncline allowed the identification of 5 species of the Cheilostome and Cyclostome Bryozoans (Cellaria rigida, Cellaria sinuosa, Aimulosia lamellosa, Heteropora and Osthimosia) in bioclastic limestones, nodular limestones, marly and sandy limestones. The interest of Bryozoans as indicators of paleoenvironments and paleoclimates was assessed by examining current communities, in terms of depth evolution as richness and abundance, distribution of taxonomic categories zoarium types, and zooidal morphology. The depositional environment analysis of Bryozoans showed a shallow marine carbonate platform with low sedimentation energy where is registered a relatively warm paleoclimate.

Transient response to changes in uplift rates in the northern Atlas-Meseta system (Morocco)

“…Ma, in agreement with the occurrence of uplifted Eocene marine deposits in the WMM and in the axial zone of the FMA and coeval with the onset of Miocene alkaline volcanism (Fig. 10b; Salvan, 1954;El Kiram et al, 2019;El Attmani et al, 2021). Early Miocene uplift initiation could be also coeval with the onset of widespread contractional deformation in the FMA (Gomez et al, 1996;1998), in the High Atlas Mountains (El Harfi et al, 2001;Lanari et al, 2020a;2020b) and in the Rif mountains (Fig.…”

“…This includes Ordovician, Silurian, and Devonian schists and metasedimentary rocks, locally intruded by late Carboniferous granitoids (320 and 270 Ma;Hoepffner et al, 2005 and references therein). This domain is partially covered by undeformed Mesozoic and Eocene marine sedimentary rocks (e.g., Phosphatic series; Salvan, 1954;El Kiram et al, 2019;El Attmani et al, 2021). The Rif Mountains to the north reaches peaks of up to 2500 m and represents a fold and thrust belt that experienced NW-SE shortening due to the convergence of Africa and Eurasia (Jolivet and Faccenna, 2000;Abbassi et al, 2020;Agharroud et al, 2021).…”