GEOCHEMICAL CONTROLS ON CARBONATE SHELL TAPHONOMY IN NORTHERN GULF OF MEXICO CONTINENTAL SHELF AND SLOPE SEDIMENTS

Abstract

Abstract We examine the linkage between the sediment geochemical milieu and the process of carbonate degradation over a wide range of continental shelf and slope sediments using molluscan shells deployed for 13 years by the Shelf and Slope Experimental Taphonomy Initiative (SSETI). Geochemical characterization of the environment of preservation included the breadth of the pore-water carbonate undersaturation window, a depth-integrated carbonate dissolution index, the depth of minimum pore-water saturation, diffusive fluxes of oxygen and calcium, average sulfate and chloride concentration in the upper 5 cm, and the carbonate and organic carbon fractions in the same sedimentary horizon. Taphonomic indices included the maximum degree of dissolution; average dissolution; the incidences of chalkiness, pitting, deep dissolution, and a soft shell surface; the maximum degree of discoloration; the incidences of fading, gray-to-black discoloration, brown discoloration, and orange discoloration; the presence of pyri...