Post-Miocene reef faunas of the Red Sea: glacio-eustatic controls

Abstract

The Red Sea maritime rift has been discontinuously colonized by coral reefs since the Miocene. The Tethyan Miocene period of coral growth was interrupted when hypersaline conditions became established in the basin. The second period of reefal recolonization, started from the Indian Ocean, is poorly known in its Pliocene part but Pleistocene reefs are abundant throughout the entire basin. The Quaternary reefs appear strictly controlled by the Pleistocene cyclicity of ice ages which in turn modulate with the basin’s hydrological conditions. It is proposed that the shallow-silled Red Sea basin was cyclically affected by more or less severe biotic turnovers as a consequence of periods of high environmental stress (temperature, salinity) during glaciations.

The fact that the last interglacial (isotope substage 5e) coral reef fauna differs from the modern biota inhabiting the Red Sea is interpreted as a consequence of a basinal extinction event at the peak of the last glaciation due to a rise in salinity. Periods of increased humidity (rainy phases) are represented by marine benthic biota as well as proven by the occurrence in the Red Sea of early Holocene mangals, at present absent or strongly reduced in size and complexity.