Fluctuations in the carbonate production of Phanerozoic reefs

Abstract

Abstract A comprehensive database on Phanerozoic reefs is used to evaluate the carbonate production of reefs through time. Net, gross and export carbonate productions of 2760 Phanerozoic reefs are calculated and the cumulative production for 32 time slices is evaluated. The total amount of carbonate produced in the reef ecosystem in a given time slice is a function of global reef abundance, average reef size and the relative amount of carbonate exported from the reefs. Carbonate production of reefs is usually low, but characterized by prominent peaks in the mid-Silurian Givetian-Frasnian, the Late Triassic, the Late Jurassic, the mid-Cretaceous and the Neogene. The determinants of reefal carbonate production are correlated with a variety of intrinsic and extrinsic parameters such as palaeogeographic setting, dominant biota, reef type, bioerosion, petrographic composition, eustatic sea level, oceanic crust production rates, atmospheric CO 2 concentrations, and global nutrient level. The calculated carbonate production, however, is rarely correlated with particular Earth system parameters. This implies that either the controls on reefal carbonate production are too complex to allow reliable predictions, or biotic factors represent more important controls than physico-chemical parameters. The constructed curve of Phanerozoic reefal carbonate export production is also poorly correlated with proposed curves of global shallow-water carbonate production suggesting that reefs rarely contributed in a quantitatively significant way to the global carbonate budget.