Can deep ocean carbonate preservation history inferred from atmospheric pCO₂ account for ¹⁴C and %CaCO₃ profiles on the Ontong-Java Plateau?

Bulk ¹⁴C and ²¹⁰Pb_excess measurements were made on box cores from water depths of ~ 2300 and ~ 4200 m from the equator on the Ontong-Java Plateau. A sediment mixed layer thickness of approximately 6 cm and a mixing rate of 20-45 cm²/kyr are inferred from these radionuclide measurements and model simulations of their depth profiles. Using these sediment mixing characteristics, the model is then forced with a deep sea carbonate preservation history derived from an ice core atmospheric pCO₂ record, in order to examine whether the derived history can account for depth profiles of ¹⁴C age and CaCO₃ content from the deep western equatorial Pacific. Results show that ¹⁴C and %CaCO₃ data from the deep site can be simulated simultaneously with some success using the assumed carbonate preservation history and a time-varying non-carbonate flux function. However, the model is unable to use the same forcing functions to simulate the ¹⁴C and %CaCO₃ data from the shallower core. These results suggest that local carbonate accumulation is not driven simply by generalized deep water carbonate chemistry inferred from atmospheric pCO₂. Potentially important local processes and aspects of the model that may have contributed to the results are also discussed.