Potential foraminiferal markers for the Visean–Serpukhovian and Serpukhovian–Bashkirian boundaries—a case-study from Central Morocco

Abstract

The Carboniferous succession in Adarouch (Central Morocco, north of the Atlas Transform Fault) contains thick carbonate beds including upper Visean, Serpukhovian and basal Bashkirian rocks. Foraminifers enable precise recognition of the Visean/Serpukhovian (V/S), early/late Serpukhovian (eS/lS) and Serpukhovian/Bashkirian (S/B) boundaries.Insolentitheca horrida, Loeblichia ukrainica, “Millerella”spp. andEndostaffella? sp. 2 are regarded as regionally useful indices to the V/S boundary, whereasEostaffellinaspp.,Eostaffella pseudostruveiand some evolved species ofArchaediscusexhibit greater reliability for worldwide correlation of this level. Similarly, the eS/lS boundary is marked locally byBrenckleina rugosa, Eosigmoilinasp., andMonotaxinoidesspp. and globally byLoeblichia minima, Bradyina cribrostomata, Plectostaffellaspp.,Eostaffellina “protvae”and“Turrispiroides”, and the S/B boundary is marked locally byGlobivalulina bulloidesand globally bySeminovella elegantula, andNovella?. Occurrences of these taxa in Morocco allow correlations with the Moscow Basin, the Urals, the Donetz Basin and North America. The Moroccan assemblages share few taxa in common with Saharan basins south of the Atlas Transform Fault. Correlations with western European basins are difficult because of the paucity in the latter of foraminiferal-bearing carbonate strata.