Middle to late Cambrian shallow marine trace fossils from the Imfout Syncline (Western Meseta, Morocco): Palaeoecological and palaeoenvironmental significance in NW-Gondwana. (May 2017)

• Record Type: Journal Article
• Authors: Oukassou, Mostafa; Lagnaoui, Abdelouahed; Raji, Mohammed; Michard, André; Saddiqi, Omar
• Is Part Of: Journal of African earth sciences. Volume 129(2017)
• Page Start: 492
• Page End: 503
• Publication Date: 2017-05
• Subjects: Trace fossils -- Selenichnites -- Skolithos ichnofacies -- Middle-late Cambrian -- El Hank Formation -- Moroccan Meseta; 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.2017.02.006
• Languages: English
• ISSNs: 1464-343X

Abstract

Abstract: The present research provides the first evidence of invertebrate activity assigned to the ichnogenus Selenichnites occurring together with moderately diverse ichnofossils from the middle to late Cambrian of the Moroccan Meseta. The invertebrate traces occur in sandstone strata of the El Hank Formation within the Imfout Syncline, in the northern part of the Rehamna Massif (Coastal Block, western Moroccan Meseta). Bedding surfaces from the top of the El Hank Formation near the Imfout Dam show diverse forms of current ripples and distincts crescentic ichnofossils in concave epirelief scattered on the surface. In this section, the traces provide evidence of the ethology of an organism inhabiting the relatively shallow waters of the area during this time. Selenichnites co-occurs with the ichnogenera Arenicolites, Diplocraterion, Lingulichnus, Monocraterion, Skolithos and unidentified burrows, and the ichnoassemblage is referred to the Skolithos ichnofacies. These traces can be referred to arthropods (e.g. polychaete worms and amphipod crustaceans), lingulid brachiopods, annelids and/or phoronids. The Imfout Selenichnites represents the first occurrence of this ichnogenus from the Cambrian of the Moroccan Meseta, and the second from the Cambrian deposits of Morocco. The potential tracemakers are still questionable, but were most likely xiphosurans, trilobites, euthycarcinoids or crustaceans. If so, the Imfout traces could be among the oldest pieces of evidence for the presence of horseshoe crabs during the Cambrian. The combination of sedimentological and ichnological data indicates that the El Hank Formation was deposited in a sublittoral soft ground environment next to a sandy shore. It was originally part of an early Palaeozoic shallow marine epicontinental platform in west-central Morocco. In addition to the equivalent Cambrian deposits from the Anti-Atlas, the El Hank Formation constituted a part of the northern Gondwana platform domain during the transgression coming from the Rheic Ocean onto the West African Craton margin. Graphical abstract: Highlights: Selenichnites occurs together with moderately diverse ichnofossils in the middle to late Cambrian of Morocco. First report of the ichnogenus Selenichnites from the Cambrian of Moroccan Meseta. Imfout Selenichnites may be among the oldest pieces of evidence for horseshoe carbs. Sedimentological and ichnological analysis suggests a shallow marine epicontinental platform setting in northern Gondwana.