Reconnaissance Geology of the Inner Continental Shelf, Cape Fear Region, North Carolina

摘要

The Inner Continental Shelf off the North Carolina coast between the South Carolina border and Cape Lookout, North Carolina, was surveyed to obtain information on bottom and subbottom sediment deposits and structures. The location and the extent of deposits of sand suitable for restoration and nourishment of nearby beaches were investigated. Primary survey coverage consisted of 824 kilometers (445 nautical miles) of seismic reflection survey and 139 cores ranging in length from 0.6 to 6.1 meters (2 to 20 feet). More than half of the area surveyed is underlain by two thick sections of Coastal Plain sediments characterized by seaward-dipping progradational internal beds which generate a characteristic acoustic pattern on seismic reflection records. These beds are exposed on the shelf floor in places and elsewhere are covered by a thin sediment blanket. Samples of these extensive units indicate that one is of Cretaceous age and the other of Oligocene age. Both units consist predominantly of fine quartz sand. Other sediment units closely underlying the shelf floor consist of planar-to complex-bedded sheet and channel-fill deposits of predominantly quartz sand or biogenic calcium carbonate. These deposits range in age from Eocene to Holocene. Modern sediment accretion on the inner shelf appears to be largely restricted to the shoal fields off Cape Lookout and Cape Fear, and to inlet shoals along the coast.