Sedimentary carbonate record of calcium-magnesium cycling

Abstract

Mass-age data on sedimentary carbonate sequences define decay parameters for principal reservoirs which, in conjunction with tabulated dolomite abundances, allow for the determination of Ca and Mg sediment fluxes over the past 560Ma. Mass-age and composition data require an average Mg flux of 1.8 × 1018m/Ma to dolostone reservoirs. Although hydrothermal alteration at ocean ridges is presently the dominant sink for seawater Mg, dolomite precipitation accounted for nearly the entire inventory of riverine Mg over much of Phanerozoic time. -from Authors