Principles of Carbonate Sedimentation

Abstract

Most, though not all, carbonate sedimentation results basically from chemical or biochemical processes occurring in a special marine environment: one of clear, warm, shallow water. A world map (Fig. I-1) showing areas of modern carbonate deposition demonstrates clearly a positive correlation between such deposition and the equatorial belt and areas of warm ocean currents. Fairbridge (Chilingar et al., 1967, p. 404) presented a graph showing that neritic carbonates exist chiefly north and south of the equator below latitudes of 30 degrees. Furthermore, whereas the bottoms of deep ocean basins between 40 degress north and south latitudes contain much planktonic carbonate, those in higher latitudes do not, except in the north Atlantic along the Gulf stream. Invertebrates precipitate thicker calcite and aragonite shells in clear, warm waters, many more calcareous algae thrive there, and algal-dependent hermatypic or reef-building corals are restricted to such an environment. Cooler marine waters do support swarms of invertebrates whose tests and shells may form local accumulations of shelly lime sand (Lees, 1973; Chave, 1967), but other types of lime sediment, such as ooids, grapestones, peloids, reefy boundstone and lime mud accumulations, are confined to tropical and subtropical waters.