A new early Visean coral assemblage from Azrou-Khenifra Basin, central Morocco and palaeobiogeographic implications

Sergio Rodríguez,Felipe González,Ismael Coronado,Ismail Said,Pedro Cózar,Mohamed El Houicha,Javier Sanz-López,Ian D Somerville

doi:10.1186/s42501-019-0051-5

Abstract

A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the Azrou-Khenifra Basin, northwest of Khenifra, central Morocco. The newly discovered Ba Moussa West (BMW) coral fauna includes Siphonophyllia khenifrense sp. nov., Sychnoelasma urbanowitschi, Cravenia lamellata, Cravenia tela, Cravenia rhytoides, Turnacipora megastoma and Pleurosiphonella crustosa. The early Visean age of the coral assemblage is supported by foraminiferal and conodont data, with the recognition of the basal Visean MFZ9 Zone. This confirms that the first transgression in the Azrou-Khenifra Basin was during the earliest Visean. The allochthonous coral assemblage was recovered from coarse-grained proximal limestone debris flow and turbidite beds within a fault-bounded unit, lying to the west of a thrust syncline containing upper Visean limestones. No evidence exists of the former early Visean shallow-water platform from which the corals were derived. All other in situ platform carbonate rocks around the southern margin of the Azrou-Khenifra Basin are probably of late Visean (Asbian–Brigantian) age. The early Visean Ba Moussa West coral fauna can be compared with that at Tafilalt in eastern Morocco, as well as in other Saharian basins of Algeria. Many of the genera and species in the Ba Moussa West assemblage are identical to those in NW Europe, with which it must have had marine connections. The new rugose species described, Siphonophyllia khenifrense, is probably endemic to North Africa. Its ecological niche in NW Europe was occupied by S. cylindrica or S. aff. garwoodi.

Highlights

Mississippian rocks are common in the Moroccan Meseta
8 Conclusions A new early Visean coral assemblage has been discovered transported in the rhythmic facies deposits of the southern part of the Azrou-Khenifra Basin, northwest of Khenifra, Morroco
The early Visean age of the coral assemblage is supported by microfossil data, which confirms a previous hypothesis that indicated a first transgression during the early Visean in the Carboniferous of the Meseta

Summary

Introduction

Mississippian rocks are common in the Moroccan Meseta. They have been studied and described by French geologists since the beginning of the twentieth century (Lecointre 1926; Termier 1936; Termier and Termier 1950; Gigout 1951, etc.). The Mississippian stratigraphic successions are clearly different in the western and in the eastern parts of the Meseta. The stratigraphy in both areas, as well as in other regions from Morocco, has been summarized by Beauchamp and Izart (1987), Hoepffner et al (2005) and Michard et al (2010). The microfossil content was studied to enhance the biostratigraphic discussion and significance of the coral fauna

Objectives

Methods

Conclusion