Coral reefs in a clastic sedimentary environment: Fossil (Miocene, S.W. Turkey) and modern (Recent, Red Sea) analogues

Summary

The Miocene sequences of southwestern Turkey and the Recent Red Sea are characterised by an unusual and distinct sedimentary association. In both cases near-shore patch and fringing reefs occur along the margins of alluvial fans and braidplains developed under semiarid climatic conditions. In such an environment reef location, morphology and internal structure are controlled primarily by the clastic sedimentary system rather than the independent growth of the framework builders as in normal reef environments. The primary control is a morphological one, the reefs adopting the overall geometry of the sediment body forming a fan shaped arcuate belt. Irregularities in reef morphology are clearly related to the presence of fluvial channels on the fans. The coarse grained gravel of the fans provide an ideal substrate for coral colonisation, this is reflected in the lack of a pioneer community in the Miocene reefs. Periodic rapid burial of the reefs terminates the production of carbonate debris by mechanical and biological erosion resulting in preservation of a relatively unaltered primary framework. The inter-reef sediment consists exclusively of terrigenous sediment.