Lecture
IGA Lecture: Ian Somerville (UCD) - Coral reefs and biostromes from Carboniferous limestones of Morocco: faunal composition, palaeoecology and palaeobiogeographic domains
Abstract
Over the last decade, field work in Morocco investigating Lower Carboniferous (Mississippian) limestones has led to some significant faunal discoveries. In the Tiouinine area of north central Morocco a well exposed Upper Viséan coral framework reef has been identified, which is a first for the Lower Carboniferous in North Africa and possibly the world. It contains a rich assemblage of rugose and tabulate corals with support provided by calcareous algae. Its development comes at a time when reefs were slowly recovering from the mass extinction event in the Late Devonian. Rugose corals also formed laterally extensive biostromes in the Tindouf Basin in southern Morocco. A lower horizon is dominated by several species of Siphonodendron, however an upper biostrome at the top of the marine sequence contains a rich and diverse assemblage with several new species recorded. Interestingly, the age of this biostrome according to the foraminiferal dating is Bashkirian (Early Pennsylvanian) when many rugose genera and species were supposed to have become extinct. Clearly in Saharan basins they were able to survive in refugia. Another remarkable aspect of this younger biostrome is that it has been recognised in other Saharan basins in Algeria and Mali several hundred kilometres to the east and south, highlighting the widespread nature of shallow water platform carbonates on the northern margin of Gondwana.