THE HOLOCENE PRESERVATION HISTORY OF EQUATORIAL PACIFIC SEDIMENTS

A model of the sediment mixed layer is used to quantify the glacial-Ho locene changes in calcite preservation (productivity minus dissolution ) at water depths that span the transition between lysocline and calci te compensation depth in the equatorial Pacific. The mean preservation fluxes required by the model to account for the observed changes in s ediment composition indicate, in most cases, that calcite dissolution exceeds supply and that there has been net removal of calcite from sur face sediments over the Holocene. The sediment mixed layer is therefor e not at steady state with respect to CaCO3 fluxes. The model is also used to show that an observed increase in the radiocarbon age of the c ore top sediments with increasing extent of-dissolution cannot be expl ained by chemical erosion of underlying glacial material. Dissolution taking place at or just below the sediment-water interface is the prob able cause of this phenomenon.