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

Abstract

Potential foraminiferal markers for the Visean-Serpukhovian and Serpukhovian-Bashkirian boundaries- A case-study from Central MoroccoThe 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. and Endostaffella? sp. 2 are regarded as regionally useful indices to the V/S boundary, whereas Eostaffellina spp., Eostaffella pseudostruvei and some evolved species of Archaediscus exhibit greater reliability for worldwide correlation of this level. Similarly, the eS/lS boundary is marked locally by Brenckleina rugosa, Eosigmoilina sp., and Monotaxinoides spp. and globally by Loeblichia minima, Bradyina cribrostomata, Plectostaffella spp., Eostaffellina "protvae" and "Turrispiroides", and the S/B boundary is marked locally by Globivalulina bulloides and globally by Seminovella elegantula, and Novella?. Ocurrences 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.