Invoking carbonate ramp theory for insights into US South-Atlantic margin carbonate sediment behavior

The East Coast of the United States is unique from many other offshore energy-producing regions as it extends over a large latitudinal range resulting in a high degree of soil variability. This includes carbonate sediments which are prevalent in the offshore region south of North Carolina and in the vicinity of offshore wind call areas recently leased through the United States Bureau of Ocean Energy Management. Carbonate sediments are common in low latitude offshore environments, biogenic in nature, and largely composed of the skeletal remains of calcium carbonate bearing marine micro- and macro-organisms (foraminifera, coccolithophore, coral, mollusks, etc.) and their bioclasts. These sediments accordingly have large variation in grain size, shape, and structure, ranging from round and plate-like to porous and hollow. Carbonate sediments have traditionally been problematic for offshore oil and gas developments due to the high compressibility and low cyclic strength. To date, no offshore wind developments have been built on carbonate sediments and it is not yet certain how they will impact foundation design due to differences in loading conditions between oil and gas and offshore wind. This paper presents a review of carbonate sediments offshore the Southeast Coast of the United States from public databases, comparing these sediments to other well-known carbonate deposits, and discusses the implications for offshore wind development in this region.