Cambrian microfossils from the High Atlas, Morocco: Taxonomic, biostratigraphic, palaeobiogeographic, and depositional significance of the Brèche à Micmacca limestone beds. (January 2023)

• Record Type: Journal Article
• Authors: Mghazli, Kamal; Lazreq, Nezha; Geyer, Gerd; Landing, Ed; Boumehdi, Moulay Ahmed; Youbi, Nasrrddine
• Is Part Of: Journal of African earth sciences. Volume 197(2023)
• Publication Date: 2023-01
• Subjects: Cambrian -- High atlas -- Biostratigraphy -- Palaeobiogeography -- West gondwana -- Molluscs -- Systematic palaeontology; Earth sciences -- Africa -- Periodicals; Earth sciences -- Middle East -- Periodicals; Geology -- Africa -- Periodicals; Geology -- Middle East -- Periodicals; Sciences de la terre -- Afrique -- Périodiques; Sciences de la terre -- Moyen-Orient -- Périodiques; Géologie -- Afrique -- Périodiques; Géologie -- Moyen-Orient -- Périodiques; Earth sciences; Geology; Africa; Middle East; Periodicals; Electronic journals; 556.05
• DOI: 10.1016/j.jafrearsci.2022.104751
• Languages: English
• ISSNs: 1464-343X

Abstract

Abstract: Diverse helcionelloid molluscs, probable polychaetes, and sclerites of other metazoan groups are described from the Brèche à Micmacca Member at section Le IX in the Lemdad syncline in the High Atlas, southern Morocco. The collections include more than 3, 000 specimens and complement earlier described faunal assemblages from this interval. The new material includes 21 species of 13 genera, with 15 helcionelloid species (or forms), one supposed orthothecid hyolith, and 5 pseudopelagielliform species. They record a relatively limited amount of biotic change through the Morocconus notabilis and Ornamentaspis frequens trilobite biozones in the Souss Basin. Eotebenna cf. papilio Runnegar and Jell1976, is the first record of the genus in Africa and West Gondwana. Dorispira ? lemdadensis n. sp., Yochelcionella longituba n. sp., and Yochelcionella gracilituba n. sp. are proposed. The Le XI associations are compared with those from other localities of the Brèche à Micmacca Member in terms of their biostratigraphic and palaeoecological implications. The assemblages include forms that are similar to those from coeval faunas from the Siberian Platform, North China, Australia, and Laurentia (SNAL) and assist in interregional and continental biostratigraphic correlation and the understanding of palaeogeographic connections. This study concludes that Lower–Middle Cambrian boundary interval trilobites and small shelly fossils comprise a West Gondwanan assemblage (i.e., Morocco, Iberia, Saxo-Thuringia) that differs from palaeogeographically distant coeval faunas from tropical SNAL regions. Graphical abstract: Image 1 Highlights: The section Le XI in the Lemdad syncline of the High Atlas provided Helcionelloids and pseudopelagiellids faunas from Morocconus notabilis and Ornamentaspis frequens biozones. Eleven taxa are identified for the first time in Morocco. Dorispira ? lemdadensis n. sp., Yochelcionella longituba n. sp., and Yochelcionella gracilituba n. sp. are new. The occurrence of Eotebenna is the first record of this genus for Morocco, Africa and West Gondwana. The Brèche à Micmacca Member in the Atlas permit a stratigraphically refined insight into the Stage 4–Wuliuan.