Carbonate Shorelines and Shelves

Abstract

This article is a review of the calcium carbonate-rich sediments that accumulate on present-day shelf seas of the world. These sediments form the majority of limestones and dolomites in the geological record. They are produced by three different pathways of precipitation of calcium carbonate out of sea water; biotically induced, abiotic and biotically influenced precipitation. These processes occur in four main sites of carbonate sediment production, known as carbonate factories; warm shallow tropical, cold-water, microbial and pelagic. Shelf morphology has a strong influence on sediment type and distribution and flat-topped, steep sloped platforms and gently sloping ramp platforms or shelves are both investigated. Four examples of carbonate shelves are presented so as to represent the range of different shelf carbonate sediments that occur today and in the geological past: semihumid rimmed carbonate shelves of south Florida and the Bahamas, the arid carbonate ramp of the Arabian Gulf, and the cool-water, distally steepened ramp of the north-east Atlantic. Finally, the affects of anthropogenically-driven changes in climate, ocean chemistry and sea-level are discussed. These generally have a negative impact on the production and accumulation of shelf sea carbonate sediment.