Reefs (Biogenic)

Reefs are in situ organic deposits which exhibit different sizes from few cubic meters to several hundreds of kilometers length and even several hundreds of meters in thickness (Spalding et al., 2001). Modern reefs are formed predominantly by stony corals which is the equivalent of the taxonomic order Scleractinia. Corals and other calcifying organisms produce hard skeletons, which lead to the accumulation of biogenic carbonates as a result of individual growth, bioerosion, sedimentation, and cementation due to wave energy during several hundreds of years. On millennial and much longer timescales, sea-level changes are the major driving force of reef growth. Today coral reefs cover more than 284,000 km2 (Spalding et al., 2001) and they are the largest marine structures on earth formed by biota, having a long geological record and ..