Aboussalam & al. Devonian of Immouzer-du-Kandar The unique Devonian of Immouzer-du-Kandar (Middle Atlas basement) – biostratigraphy, faunas, and facies development ZHOR SARAH ABOUSSALAM, RALPH THOMAS BECKER, JULIA RICHTER, SVEN HARTENFELS, AHMED EL HASSANI & STEPHAN EICHHOLT Fig. 1: View (from the hill at Douar Ahmed-ben-Mellouk) on Devonian exposures of Immouzer-du-Kandar (hill rising from Chabat el Jenanet, Sections C2 and C3 of CYGAN et al. 1990), our Section C4, with outcrop of the lower Emsian conglomerate (Chabat Jenanet Formation) along and above the track, faulted upper Emsian to lower Givetian limestones in the lower slope (new Ahmed-ben-Mellouk Formation), the reef breccia forming a small terrace ca. 2/3 upwards, and the Famennian upper slope (new Chabat el Hallouf Formation, Section C5) towards the top. The slope to the left (NNE) is occupied by Triassic red beds. Section numbers are marked in circles. 1. Introduction Mesozoic Middle Atlas, with the best and most important outcrops in the tectonic window The Middle Atlas divides the Moroccan (“boutonnière”) at Immouzer-du-Kandar, ca. Meseta into the Western and Eastern Meseta, 40 km S of Fès. The wooded Jebel Kandar to which differ strongly in the Devonian in terms the SW is a more than 1600 m high mountain of facies and synsedimentary structural built of Jurassic strata (Fig. 2). Fossiliferous geology (e.g., overviews of EL HASSANI & Ordovician to Lower Carboniferous BENFRIKA 1995, 2000). There is restricted formations crop out to the NW, from Dour knowledge of the Palaeozoic basement of the Rouda towards the SE, the Chabat el Jenanet, Hassan II Academy of Science and Technology Frontiers in Science and Engineering - Vol. 10 - n° 1 - 2020 127 Aboussalam & al. Devonian of Immouzer-du-Kandar and then towards the Chabat al Sitout (Fig. 4) 2006 for overview)). There are coarse The Devonian litho- and biostratigraphy of the conglomerates and slump masses with “alien” area has been established by the CHARRIÈRE & (e.g., TAHIRI et al. 2017) magmatic rocks, RÉNAULT (1989) and CYGAN et al. (1990; Fig. which must have been derived from a proximal 3). Comparisons with other Meseta regions Neoproterozoic to Lower Palaeozoic source. showed from the beginning that the succession This differs considerably from the basement of includes many unique sedimentological units, other Meseta regions. Therefore, any new faunas and floras (FAIRON-DEMARET & stratigraphical, sedimentological, REGNAULT 1986), which isolate it both from palaeontological, and geochemical data add to the closest Devonian of the East-Central the knowledge of a crucial segment of Meseta Meseta (e.g., PIQUE & MICHARD 1981; Azrou- palaeogeography and tectonics. However, the Khenifra nappes) and from the predominantly Immouzer-du-Kandar Devonian may represent siliciclastic Eastern Meseta e.g., at Tazekka, a transported, allochthonous unit, as the nappes which is separated by the Tazekka-Bsabis- of the Azrou to Khenifra region. Bekrit Fault Zone (see HOEPPFNER et al. 2005, Fig. 2: Position of the Jurassic Jebel Kandar and the Jenanet succession (red dot for Fig. 1) in the SW corner of topographic sheet, 1: 50 000, NI-30-VIII-3c, Sefrout. 128 Hassan II Academy of Science and Technology Frontiers in Science and Engineering - Vol. 10 - n° 1 - 2020 Aboussalam & al. Devonian of Immouzer-du-Kandar By detailed section logging, conodont and OUARHACHE (1987): Unpublished thesis on macrofauna sampling, as well as microfacies the Palaeozoic to Triassic at the NW margin analyses in the last ca. 10 years, we can of the Middle Atlas S of Fés. significantly refine the local litho- and CHARRIÈRE (1989) and CHARRIÈRE & biostratigraphy and provide a more precise RÉGNAULT (1989): Principles of Devonian reconstruction of facies changes, sea-level, and Carboniferous litho- and biostratigraphy and local influences of global events, for of Immouzer-du-Kandar. example around the Emsian-Eifelian, middle- CHARRIÈRE (1990): Unpublished Ph.D. upper Givetian, and Frasnian-Famennian Thesis on the Hercynian evolution of the boundaries. The studied sections begin in the Middle Atlas basement, with detailed data for branching valley of Chabet el Jenanat and Immouzer-du-Kandar. ascend the western slope of the hill just to SE, WILLEFERT & CHARRIÈRE (1990): Detailed reaching up to the crest (Figs. 1, 2, 4; at x = description of Ordovician and Silurian litho- 541.8, y = 352.3; GPS N33°45´58.4´´, and graptolite biostratigraphy. W4°56´50.9´´). There are numerous normal CYGAN et al. (1990): Conodont faults, which offset especially the upper biostratigraphy of Emsian to lower Frasnian Emsian to Givetian succession at close units at Immouzer-du-Kandar and their distance (Fig. 1). These had to be respected in significance for the understanding of the order to avoid mistakes in the small-scale sedimentary evolution and palaeogeography lateral correlations. of the region. RACHEBEUF (1990a, 1990b): Record of the 2. Research History chonetids Ctenochonetes robardeti and Plicanoplica carlsi from lower Emsian grey HORON (1954): First (unpublished) report on shales of Immouzer-du-Kandar. fossiliferous Silurian (with graptolites) to OUARHACHE et al. (1991): Records of Upper Lower Devonian (with brachiopods) strata at Viséan foraminifers, calcareous algae Immouzer-du-Kandar, followed by a Viséan (Koninckopora), and “pseudo-algae”, such as transgression. Palaeoberesella, Kamaena, Stacheia, and CHARRIÈRE & RÉGNAULT (1983) and Aoujgalia. CHARRIÈRE et al. (1984): Preliminary notes on EL HASSANI & BENFRIKA (1995, 2000): the Immouzer-du-Kandar Devonian litho- and Overviews of the Devonian of the Moroccan biostratigraphy. Meseta, including a summary for the Middle BRICE et al. (1984): Description and Atlas basement. biostratigraphic dating of Emsian, supposed BERKHLI (1999): Discussion of the Frasnian, and upper Famennian brachiopods. foraminifer age of Viséan limestones at FAIRON-DEMARET & RÉGNAULT (1986): Immouzer-du-Kandar. Description of Lower and Middle Devonian BERKHLI et al. (2000): Brief discussion of the plant remains, with implications for microfacies of Upper Viséan limestones of stratigraphy (Fig. 3) and palaeobiogeography. Immouzer-du-Kandar in the frame of a RÉGNAULT & CHAUVEL (1987): Description general discussion of Lower Carboniferous of the first Lower Devonian carpoid of sedimentologie and geodynamics of the NE Morocco from the Aïn el Beida Formation, Meseta. representing probably a new (un-named) SARTENAER (2000): Re-assignment of genus of the Anomalocystitida (Mitrata). supposed Planovatirostrum sp. described by Hassan II Academy of Science and Technology Frontiers in Science and Engineering - Vol. 10 - n° 1 - 2020 129 Aboussalam & al. Devonian of Immouzer-du-Kandar BRICE et al. (1984) to the new genus of sediments with a terrestrial, coastal, Phacoiderhynchus. siliciclastic inner shelf, carbonate platform, JANSEN (2001): Brief comments on some of seamount, and deep pelagic origin (compare the Pragian brachiopods (Euryspirifer) CHARRIÈRE & RÉGNAULT 1989, tab. 1). The described by BRICE et al. (1984). presence of several coarse reworking units MICHARD et al. (2008): Reference to the proves significant synsedimentary tectonic Chabat Jenanat conglomerate with reworked movements and active, steep fault scarps in granites, ignimbrites, Ordovician quartzites, the source region of material, from where and Silurian slates. mass flows moved downwards. The deep GERRIENE et al. (2010): Reference to the erosion into Neoproterozoic basement and the possible occurrence of the aneurophytalean perfect rounding of pebbles show that an genus Rellimia in the “plant shale” at adjacent island must have existed, where Immouzer-du-Kandar. material was constantly moved in fluviatile or BECKER (2012): Illustration of the Eovariscan coastal environments, prior to transport and breccia at Immouzer-du-Kandar, as an downslope re-deposition. Parts of the example for double reworking. topographic high were deeply drowned BECKER & ABOUSSALAM (2014): Brief leading to condensed cephalopod limestone reference to the distinctive upper Givetian to accumulation on a former seamount. But middle Frasnian facies at Immouzer-du- during highstands, pelagic anoxic to euxinic Kandar. conditions developed. Upslope, along the SCHWERMANN (2014): Unspecified record of island shoals, a top Middle to basal Upper shark teeth in Frasnian samples from Devonian reef existed, which was later Immouzer-du-Kandar. uplifted and completely eroded. These strong RICHTER et al. (2016): Preliminary new contrasts indicate in total a tectonically highly conodont data for the Emsian/Eifelian and active shelf basin slope near to one or more upper Famennian at Immouzer-du-Kandar. islands. After the complex Eovariscan period, BECKER et al. (2016): Brief reference to the the Viséan strata can be better placed in the discovery of upper Givetian goniatites at palaeogeographic context of adjacent Immouzer-du-Kandar. successions (e.g., BERKHLI et al. 2000). RICHTER (2017): Unpublished M.Sc. Thesis on the upper Emsian to Eifelian and upper 4. Litho- and biostratigraphy Famennian carbonate succession. Our new studies concentrated on the TAHIRI et al. (2017): Geochronological dating Emsian to Famennian interval (Fig. 4), but for of granite clasts within the Chabat Jenanet the sake of completeness, earlier and later Conglomerate as Ediacarian and Cambrian. intervals are included and briefly reviewed COZAR et al. (2019): Discussion of based on literature data. Immouzer-du-Kandar Viséan foraminifers in the context of survival and/or