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

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

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...

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Bibliographic Details
Published in:Journal of African earth sciences (1994) Vol. 197; p. 104751
Main Authors: Mghazli, Kamal, Lazreq, Nezha, Geyer, Gerd, Landing, Ed, Boumehdi, Moulay Ahmed, Youbi, Nasrrddine
Format: Journal Article
Language:English
Published: Elsevier Ltd 01-01-2023
Subjects:
Biostratigraphy
Cambrian
High atlas
Molluscs
Palaeobiogeography
Systematic palaeontology
West gondwana
Cambrian
Molluscs
West gondwana
Palaeobiogeography
Systematic palaeontology
High atlas
Biostratigraphy
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Summary: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. [Display omitted] •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.
ISSN:1464-343X
1879-1956
DOI:10.1016/j.jafrearsci.2022.104751