Devonian conodont and ammonoid succession of the eastern Tafilalt (Ouidane Chebbi section), Anti-Atlas, Morocco (original) (raw)
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Proceedings of the Subcommission on Devonian Stratigraphy (SDS) - IGCP 421 Morocco Meeting
Detailed sampling of late Emsian-early Givetian sections south of Tiflet (NW Meseta, Morocco) reveals serotinus through lower varcus Zone conodonts (timorensis and rhenanus/varcus zones) and allows recognition of the base of the Eifelian and an approximate positioning of the base of the Givetian. Dark greyish shales and limestones close to the boundary between the partitus-costatus Zones may be related to the Chotec Event. Deepening and shallowing trends based on the succession of different conodont biofacies are in agreement with the late Emsian-early Givetian sea level curve of JOHNSON et al. (1985). Ozarkodina bidentata is the only Mesetan conodont species that was not recorded from the Anti Atlas. RESUME L'échantillonnage détaillé de coupes au sud de Tiflet (NW Meseta, Maroc), couvrant un intervalle Emsien supérieur-Givétien inférieur, relève la présence des conodontes de la Zone à serotinus jusqu'à la Zone à varcus inférieure (Zones à timorensis et à rhenanus/varcus). La base de l'Eifelien est reconnue avec précision, celle du Givétien est approximativement fixée. Un niveau à schistes et calcaires grisâtres foncés, près de la limite entre les Zones à partitus et costatus, correspond probablement à l'événement Chotec. Des changements dans la profondeur du milieu marin déduits de la succession des biofacies à conodontes sont en accord avec la courbe du niveau marin établie par JOHNSON et al. (1985) pour l'intervalle étudié. Ozarkodina bidentata est la seule espèce dans les faunes à conodontes de la Meseta qui n'est pas connue dans l' Anti Atlas. Brachiopodes du Silurien supérieur et du Dévonien inférieur (Praguien probable) de Khémis n'Ga (région de Safi) , Maroc. Denise BRICE Mots clé : Brachiopodes, Silurien supérieur-Pridoli, Dévonien inférieur-Praguien probable, Maroc. RÉSUMÉ Les brachiopodes étudiés proviennent de niveaux appartenant aux deux unités d'un ensemble carbonaté paléozoïque situé à Khemis-n'Ga, région de Safi, Maroc, transgressif sur l'Arénig, découvert et décrit par BEUN & HUVELIN (1986, 1992). Les brachiopodes de l'unité inférieure sont peu diversifiés, appartiennent surtout aux rhynchonellida et aux genres Clarkeia et Diabolirhynchia, et indiquent un âge silurien supérieur (Pridoli) ; ceux de l'unité supérieure, nettement plus diversifiés mais peu abondants, indiquent un âge dévonien inférieur, Praguien probable, ils ont des affinités marquées avec les faunes praguiennes de Bohême.
CONODONT COLOR ALTERATION PATTERNS IN DEVONIAN ROCKS OF THE EASTERN ANTI-ATLAS, MOROCCO
JOURNAL OF AFRICAN EARTH SCIENCES, 1991
The thermal and burial hisms7 of the eastern Anti-Atlas chning Late Palaeozoic time b mvestigated using conodont colour alteration d.t~ and the elecCee spin ~ technique (ESR). Both the conodom colonr alteration index (CAI) patterns and the results of ESR investigations indicate that the Devonian rocks of the eastern Anti-Arias attained theirIxesent-daymamrationlevel during C~xmife~m~ time prior to V~m uplift. The ~ CM v~ fxom 3 m 5 reflect heating to tcmpcnm~ of 120 °C and 310 *(2 respectively.
Stratigraphy and tectono-sedimentary processes of allochthonous and autochthonous Devonian deposits of the Tisdafine Basin, Eastern Anti-Atlas, Morocco, 2022
The Tisdafine Basin lies in the Eastern Anti-Atlas (southern Morocco), north of the Proterozoic Saghro-Ougnat massifs, in the Gondwana craton-western Variscid Meseta contact zone. Despite this crucial structural position, its allochthonous and autochthonous Devonian successions have been poorly studied. As an interdisciplinary tectono-sedimentary approach, field investigation, high-resolution biostratigraphy, microfacies analysis, clay mineralogy, and investigations of syn- and postsedimentary tectonic movements were used to reconstruct the Devonian basin history. Results from the wider Tinejdad region are used for comparisons with the Devonian south and east of the Proterozoic belt (northern Maïder and Tafilalt). In the western Bou Tisdafine region, the lower Emsian olistolite which is embedded in the upper Tournaisian-Visean Aït Yalla Formation remnants a shallow pelagic carbonate platform developed at the southern basin margin. A second olistolite preserved the transformation from Eifelian neritic trilobite limestone, resembling the northern Maïder region, to a condensed, mostly pelagic Givetian to middle Famennian platform. Breccia marker beds testify to the widespread Givetian/basal Frasnian synsedimentary tectonics from the Meseta to Eastern Anti-Atlas. During the FrasnianFamennian/boundary, the Upper Kellwasser Event interval is typically developed as dark goniatite limestone, followed after a sort gap by the occurence of Famennian griotte facies. The Bou Tisdafine Upper Devonian becames separated from the southern parts of the Eastern Anti-Atlas by the emerged Ougnat massif. In the eastern part of the basin, the Oued Ferkla Devonian is an isolated, large glide block derived from a western continuation of the Tafilalt Platform. Its fluctuating upper Emsian to middle Givetian pelagic facies records platform pro- and retrogradation phases, controlled by sea-level changes known from the Tafilalt, with a fine representation of the global Daleje, Choteč, Kačák, and Pumilio Events. Eifelian synsedimentary tectonic pattern correlates with the contemporaneous crustal disintegration of the whole region. The change from upper Givetian to middle Frasnian thick marls suggests a southern basin extension during the widespread tectonism of that interval. The adjacent Koudiat Inegh succession represents the true facies of the eastern Tisdafine Basin. It is characterized by black shales and distal turbiditic limestones, with a very strong diagenetic overprint (common late dolomitization) and a deformation style (with cleavage), which differs strictly from the contemporaneous beds of the glide blocks. The transition from platform to basin occurred close the base of the Eifelian, as part of the overall structural differentiation. Basinal facies persisted in the Upper Devonian. Unfortunately, the early (Emsian-middle Famennian) and main (upper Tournaisian-Visean) phases of the basin and its southern margin are separated by a gap of outcrop and strata.
Bulletin of Canadian Petroleum Geology, 2002
Recent debates concerning the origin of Emsian carbonate mud buildups exposed at Hamar Laghdad in the eastern Anti-Atlas of Morocco centre around geochemical studies that suggest authigenic or chemosynthetic processes induced precipitation of mud from hydrothermal fluids. Geochemical data alone cannot be used to demonstrate conclusively the origin of the mud comprising the buildups, but an in situ source and early cementation can be inferred from morphology, internal architecture, and sedimentary structures.
Regurgitated ammonoid remains from the latest Devonian of Morocco
Swiss Journal of Palaeontology
Accumulations of ammonoid shell fragments have been recovered from the Hangenberg Black Shale (latest Devonian) of the southern Maïder (eastern Anti-Atlas, Morocco). They are here interpreted as regurgitalites and ascribed tentatively to gnathostomes as possible tracemakers. The recognition of fossil regurgitations is reviewed and a checklist provided.
Late Early Devonian ostracodes from the Torkoz area (SW Morocco) and the Emsian/Eifelian boundary
PalZ
A new rich and diversified ostracode fauna from the Torkoz area (section Hassi Mouf South, Moroccan Anti-Atlas) is described and the ostracode distribution near the Early/Middle Devonian boundary is discussed. This ostracode fauna of a single limestone bed yields 32 taxa and is compared with the less-diversified ostracode fauna from an adjacent parallel section Hassi Mouf South as well as with a published conodont-bearing sample from section Torkoz. All three ostracode faunas are closely related, and therefore, the same latest Emsian age is postulated. Palynomorphs (acritarchs and prasinophytes) from section Torkoz support this late Early Devonian age and the scarce brachiopod fauna of the equivalent level from section Hassi Mouf South suggests a stratigraphical position very close to the Emsian/Eifelian boundary, probably latest Emsian. Zygobeyrichiasubcylindrica from a thin marly bed embedded in shales, slightly below the ostracode-rich sample from section Hassi Mouf South, and th...
Open Geosciences, 2020
This sedimentological and palaeontological analysis of the Aptian–Albian sedimentary succession of the Ait Ourir basin in the High Atlas Mountains of Marrakesh in Morocco provides new data from a previously poorly understood basin. The palaeoenvironmental evolution is deduced based on a facies analysis allowing the restoring of depositional environments and their stratigraphic architecture. Within the Aptian–Albian succession, we distinguish two sedimentary sequences separated by a major discontinuity. The first sequence is composed of calcareous and dolomitic marls with the rudist Pseudotoucasia catalaunica of the Tadhart formation (upper Aptian in age) and of strongly dolomitized limestones with corals (Eugyra sp., Thalamocaeniopsis sp., and Holocystis sp.) of the Lemgo formation (uppermost Aptian in age). These two formations were formed in an internal carbonate platform (the intertidal zone to the subtidal zone). The second sequence, Albian in age, is composed of sandy limestone...
Geological Journal, 2008
The Tafilalt is one of a number of generally unexplored sub-basins in the eastern Anti-Atlas of Morocco, all of which probably underwent a similar tectono-stratigraphic evolution during the Palaeozoic Era. Analysis of over 1000 km of 2-D seismic reflection profiles, with the interpretation of ten regional seismic sections and five isopach and isobath maps, suggests a multi-phase deformation history for the Palaeozoic-aged Tafilalt sub-basins. Extensional phases were probably initiated in the Cambrian, followed by uniform thermal subsidence up to at least the end of the Silurian. Major extension and subsidence did not begin prior to Middle/Upper Devonian times. Extensional movements on the major faults bounding the basin to the north and to the south took place in synchronisation with Upper Devonian sedimentation, which provides the thickest part of the sedimentary sequence in the basin. The onset of the compressional phase in Carboniferous times is indicated by reflectors in the Carboniferous sequence progressively onlapping onto the Upper Devonian sequence. This period of compression developed folds and faults in the Upper Palaeozoic-aged strata, producing a structural style characteristic of thin-skinned fold and thrust belts. The Late Palaeozoic units are detached over a regional décollement with a northward tectonic vergence. The folds have been formed by the process of fault-propagation folding related to the thrust imbricates that ramp up-section from the décollement. Copyright © 2007 John Wiley & Sons, Ltd.