Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Abstract

Three Upper Viséan to Serpukhovian limestone formations from the Adarouch region (central Morocco), North Africa, have been dated precisely using foraminiferans and calcareous algae. The lower and middle part of the oldest formation, the Tizra Formation (Fm), is assigned to the latest Asbian (upper Cf6g Subzone), and its upper part to the Early Brigantian (lower Cf6d Subzone). The topmost beds of this formation are assigned to the Late Brigantian (upper Cf6d Subzone). The lower part of the succeeding Mouarhaz Fm is also assigned to the Late Brigantian (upper Cf6d Subzone). The Akerchi Fm is younger than the other formations within the region, ranging from the latest Brigantian (uppermost Cf6d Subzone) up to the Serpukhovian (E 1 -E 2 ). The base of the Serpukhovian (Pendleian Substage, E 1 ) is repositioned, to coincide with the appearance of a suite of foraminiferans including Archaediscus at tenuis stage, Endothyranopsis plana, Eostaffella pseudostruvei, Loeblichia ukrainica, Loeblichia aff. minima and Biseriella? sp. 1. The upper Serpukhovian (Arnsbergian Substage, E 2 ) is marked by the first appearance of Eostaffellina ex. gr. paraprotvae and Globoomphalotis aff. pseudosamarica. The biostratigraphical scheme used for the reassessment of the foraminiferal zones and subzones in the Adarouch area closely compares with that for the British succession in northern England (Pennine Region), where the stratotypes of the Upper Viséan (Asbian and Brigantian) and Early Serpukhovian (Pendleian) substages are located. Thus, a succession equivalent to an interval from the Melmerby Scar Limestone to the Great (or Little) Limestone is recognized. These assemblages are also compared to other foraminiferal zones proposed in other regions of Morocco. Several foraminiferans have been identified that are proposed as potential Serpukhovian markers for other basins in Western Europe, and compared to sequences in Russia and the Donets Basin, Ukraine.

Mississippian coral assemblages from the Khenifra area, Central Morocco: Biostratigraphy, biofacies, palaeoecology and palaeobiogeography

“…However, there are a few taxa which first appear in the Brigantian (Cf6δ Subzone) in the Tizra Formation at Adarouch (Cózar et al, 2008b), e.g. Claracrusta, Sparaphralysia and Neoprincipia.…”

“…This basin has been affected by Variscan tectonics, in particular thrusting, on the eastern side. The Adarouch area lies some 40 km NW of Azrou at the northern end of the basin, where it is surrounded by younger Mesozoic and Cenozoic rocks (Berkhli, 1999;Berkhli and Vachard, 2002;Cózar et al, 2008b).…”

“…The exceptions are the late Viséan mounds of the Erfoud region, eastern Morocco (Wendt et al, 2001) and bioherms from the Béchar Basin, W. Algeria (Pareyn, 1959(Pareyn, , 1961Bourque et al, 1995). Recently, rugose corals have been described from platform limestones and microbial mounds from the Jerada Basin (NE Morocco) (Aretz and Herbig, 2008;Aretz, 2010a,b), as well as from the Adarouch area of north central Morocco (Said, 2005;Cózar et al, 2008b;Said et al, 2010Said et al, , 2011 (Fig. 1A).…”

Foraminiferal biostratigraphy and sequence stratigraphy across the mid-Carboniferous boundary in the Central Taurides, Turkey

“…Although some of the important foraminiferal markers, such as Eosigmoilina, Brenckelina, Eostaffella postmosquensis, Eostaffella chomatifera were reported from the Upper Serpukhovian-Lower Bashkirian strata of Libya (Massa and Vachard 1979;Vachard et al 1993), Tunisia (Lys 1985), Algeria (Sebbar and Lys 1989;Mamet et al 1994;Sebbar and Mamet 1999;Sebbar et al 2000), and Morocco (Mamet et al 1966;Vachard and Tahiri 1991;Vachard and Berkhli 1992;Berkhli et al 1993Berkhli et al , 2001Cózar et al 2008), the mid-Carboniferous boundary has not been delineated by carrying out a bed-scale sampling in North Africa.…”

Carboniferous stratigraphy and depositional environments in the Ahnet Mouydir area (Algerian Sahara)

“…This zonation is well established for Eurasian correlations (Poty et al 2006) and has also successfully been applied to the northern margin of Gondwana (e.g., Lys 1979;Conrad 1984;Mamet et al 1994;Sebbar 1998;Cózar et al 2008). In our samples, foraminifers are very rare or absent in Tournaisian strata and become more abundant in Visean and Bashkirian strata or, more precisely, in the Argiles de Tirechchoumine and the Calcaires du Jebel Berga.…”