Carbonate Platform

A carbonate platform is a shallow marine setting where biological and chemical production of calcium carbonate keeps pace with subsidence, building thick limestone and dolomite successions. Two end-member geometries are recognized: the flat-topped rimmed shelf with a reef or shoal margin, such as the Bahamas and the Great Barrier Reef shelf, and the gently sloping ramp. Production concentrates in the photic zone, so the platform tracks sea level and drowns when flooding outpaces growth. Sediment is intrabasinal bioclastic and ooid grainstone plus reef framework, with little terrigenous input. Platform carbonates host major hydrocarbon reservoirs and record sea-level and ocean-chemistry history.