Mississippian-like rugose corals from a Bashkirian biostrome in the Tindouf Basin, S. Morocco

Résumé

A rich rugose coral assemblage has been recorded from a biostrome at the top of the Djebel Ouarkziz Fm. in the Tindouf Basin, S. Morocco. It is composed of 10 genera and 14 species, of which 5 are new: Dibunophyllum bipartitum, Arachnolasma sp., Palaeosmilia murchisoni, Palaeosmilia ressoti, Palastraea regia, Siphonodendron tindoufense sp. nov., Siphonodendron ouarkzizense sp. nov., Diphyphyllum maximum, Axophyllum moroccoense sp. nov., Gangamophyllum sp., Axoclisia sahariense sp. nov., Axoclisia cf. coronata, Actinocyathus sarytschevae and Actinocyathus mariae sp. nov. It represents essentially a Mississippian-type coral fauna but with some evolved species. However, its age, as determined by foraminifers, is early Bashkirian (Early Pennsylvanian). The presence of Mississippian-like corals in the Bashkirian indicates that the epicontinental basins in northern Gondwana (Saharan basins) were a refuge for coral faunas during the late Serpukhovian extinction event. The persistence of the Mississippian assemblages in the Bashkirian from northern Gondwana was probably due to a combination of warm waters and tectonic stability. The coral assemblage from the Tindouf biostrome is similar to those corals recorded from Ellesmere Island, Arctic Canada and Novaya Zemlya, Arctic Russia where similar tropical warm water conditions have been identified during the Bashkirian in the northern hemisphere