ACCUMULATION RATES OF CARBONATE PLATFORMS

The growth potential of carbonate platforms, i.e., the maximum rate at which they can aggrade vertically, is difficult to assess. To estimat e the growth potential from the conservative side and search for varia tions with time, we have compiled published accumulation rates from th e Phanerozoic. Accumulation rates vary in a pattern, with maximum rate s up to 200 m/Ma or more (not corrected for compaction) in the late De vonian, Permian, late Triassic, late Jurassic and mid-Cretaceous, sepa rated by intervals of reduced rates (e.g., Carboniferous, early Jurass ic and late Cretaceous). The most dramatic drop occurs at the Permo-Tr iassic boundary, after which there is no documented platform growth. T his pattern resembles the evolutionary rhythm of bloom and demise of r eefs and reef-builders. The observed maximum accumulation rate of 200 m/Ma (over 10(6)-10(7) yr), is probably imposed by the maximum rate of long-term relative sea level rise on passive margins, the most favora ble site for carbonate platform development. When the trend of decreas ing rates with increasing interval duration was corrected for by norma lizing all the rates to a 1 Ma interval duration, these variations rem ained. Biological factors may explain much of the observed variations.