Microbial‐sponge and microbial‐metazoan buildups in the Late Viséan basin‐fill sequence of the Jerada Massif (Carboniferous, NE Morocco)

Abstract

Three distinctive Late Viséan buildup intervals are differentiated on the southern limb of the Jerada Synclinorium. The oldest buildups (BI-1) are preserved as olistoliths in the Oued El Koriche Formation (Fm). They were located on a southern platform prior to reworking. The younger Koudiat Es-Senn Fm contains two autochthonous buildup intervals (BI-2 to BI-3). BI-1 and BI-2 buildups are large microbial-sponge buildups, BI-3 are small microbial-metazoan buildups in the capping bed succession above BI-2. All buildups are characterized by a rigid non-skeletal microbial framework. Growth of the largest BI-2 buildups started in aphotic to dysphotic conditions in a water depth significantly less than 100 m and continued into agitated shallow-water. Smaller BI-2 buildups and all BI-3 buildups are encased in grainy shallow-water carbonates. In contrast to a mostly homogeneous microbial-sponge facies below, the uppermost part of the BI-2 buildups and all BI-3 buildups consist of heterogeneous boundstones with differing frame builders. BI-1 to BI-3 buildups represent different stages within a Viséan basin-fill sequence. Carbonate sedimentation ended with the deposition of peritidal oncolitic floatstones below the unconformably overlying Namurian shales. The Jerada buildups have many features commonly associated with 'reefs'. Comparison with contemporaneous buildups shows considerable similarities to buildups from Algeria, the Eastern Moroccan Anti-Atlas and the British Isles.

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

“…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).…”

Rugose corals from the upper Viséan (Carboniferous) of the Jerada Massif (NE Morocco): taxonomy, biostratigraphy, facies and palaeobiogeography

“…Probably the most striking difference between the two flanks is the composition of the Koudiat Es-Senn Formation, which tops the Oued Es-Sassi Formation. On the southern flank it contains a single sedimentary cycle, which includes microbial-sponge buildups and small microbial-metazoan buildups (Aretz and Herbig 2008); whereas on the northern flank the formation is twice as thick, consists of two sedimentary cycles (Berkhli et al 1999), and only contains a single rugose coral patch reef in the uppermost beds ). All sedimentary cycles in the Koudiat Es-Senn Formation consist of a lower siliciclastic-dominated part and a carbonate-dominated upper part.…”

Preface: ‘Upper Palaeozoic reef complexes and carbonate platforms’

“…The evolution and distribution of mudmounds (banks), build‐ups and reefs in the Upper Palaeozoic (Carboniferous and Permian) are very much influenced by palaeogeographic configurations of land masses and oceans and the waxing and waning of the Gondwanan ice sheets on the Pangaean supercontinent (Nassichuk and Davies, ; Blakey, ). In the Lower Carboniferous, in the northern hemisphere, Waulsortian and Waulsortian‐like mudmounds and bioherms dominated by microbes, algae, bryozoans and sponges were well developed at platform/ramp margins bordering deep water basins in tropical areas of the Palaeotethys Ocean (Somerville, ; Aretz and Herbig, ; Shen and Qing, ). Increasing complexity and diversity in mudmounds were exhibited during the Mississippian from the Tournaisian to the Serpukhovian with important constructional roles played by metazoans (Webb, , ; Somerville et al ., ; Somerville, ; Aretz and Chevalier, ), and rarely, coral reefs were developed in the late Viséan (as in North Africa—Rodríguez et al ., , this volume).…”