Mass-age data on global sedimentary carbonates require that global limestone and dolostone comprise about 3,500 x 10^20 g of carbonate Ca with a cycling rate of 0.25% per million years. Epoch-interval deviations are small, suggesting relatively constant long-term rates of deposition and destruction. Best-fit curves through data on deep oceanic and shallow cratonic reservoirs indicate that shallow water limestone formation has been decreasing at a rate of about 0.7% per million years. Holocene shallow water limestone accumulation is not 60% lower than during the Mesozoic. Possible reasons for global carbonate transfer from shallow to deep setting are largely unconstrained. Biologically-medicated processes related to the Mesozoic diversification of planktic protozoans may have resulted in the progressive replacement of shallow shelly faunas by deep oceanic calcifiers as the principle sink for a finite marine carbonate flux. Conversely, decline of cratonic carbonate reservoir mass may reflect physicochemically- mediated processes related to global sea level and the extent of carbonate-saturated seas. Preliminary data indicate that ongoing carbonate transfer is also recorded by correlation between Cenozoic positions of the continents, global sea level, and the latitudinal extent of cratonic limestones. The project will: 1) compile global data on the areal extent, latitudinal setting, and vertical accumulation rates of shoal-water carbonate platforms; and 2) document relations between present patterns of shallow water carbonate accumulation and ambient fluid carbonate chemistry. Collectively, this effort will allow for the evaluation of relations between eustasy, ambient fluid saturation state, biological versus chemical precipitation processes, and global patterns of carbonate accumulation, and will directly constrain the history of surface carbonate saturation in shallow marine settings. This global data base will be of major importance to interpreting paleoclimate and understanding evolution of the ocean.
