Global carbonate accumulation rates from cretaceous to present and their implications for the carbon cycle model

Global carbonate accumulation rates on the surface of the earth, including not only platforms but also continental margin slopes and deep-sea from the Cretaceous to Present, are estimated by compiling previous geologic studies. These rates are revised, taking account of the erosional effect of the sediments on the platform and deep-sea. Long-term model carbonate fluxes from the ocean to the crust are calculated on the basis of the carbon cycle model (GEOCARB of Berner 1991). The rates based on the actual geologic data indicate much lower values than model fluxes, excluding the Pliocene and Quaternary. The discrepancy could be attributed to the two misunderstandings, namely an overestimate of carbonate accumulation rate for the Quaternary and an incorrect use of the higher Quaternary rate for a boundary condition of the model. The carbonate accumulation rate for the Pliocene to Quaternary is lowered from 29.8 × 10¹⁸ mol/Ma (modified from Opdyke & Wilkinson 1988) to 14.8 × 10¹⁸ mol/Ma in the present study, assuming that the rate from Quaternary to Pliocene is almost the same as the Miocene value. New model fluxes are recalculated with the new boundary condition in the Quaternary (14.8 × 10¹⁸ mol/Ma). Revised model fluxes show general trends of high rates in 120 Ma or 130 Ma, and a low rate in 0 Ma, and are in agreement with the accumulation rate pattern.