PRELIMINARY STRATIGRAPHIC ANALYSIS OF THE LOWER (?) CONIACIAN TO UPPER CAMPANIAN SECTION IN THE ELIZABETHTOWN CORE, EASTERN NORTH CAROLINA COASTAL PLAIN, USA

As part of the Coastal Carolina Project, the U.S. Geological Survey (USGS) is drilling a series of core holes to basement to characterize the hydrogeologic framework of North Carolina’s (N.C.) Coastal Plain. The Coastal Carolina Project is a collaboration between the USGS, N.C. Geological Survey, University of North Carolina-Wilmington, and N.C. DENR Divisions of Water Quality and Water Resources. To date, three sites have been cored - Kure Beach, Elizabethtown, and Hope Plantation. This abstract provides preliminary results of the stratigraphic analysis of the Elizabethtown core (NCGS BL-C-1-2003) which penetrated a thick (160 m) Cretaceous section.

The Elizabethtown core site is located 6.84 km south of the Cape Fear River’s classic Cretaceous outcrops (Big Sugar Loaf), at 33.3 m above mean sea level, on a dissected terrace underlain by the Pleistocene Waccamaw Formation. A goal of drilling was to recover continuous core (mud rotary) through the Cape Fear, Tar Heel, and Bladen Formations, which are poorly exposed along the river. In 2003, the USGS cored to a total depth of 172.8 m, intercepting the K/T boundary (base of Waccamaw) at 12.6 m, but not penetrating basement. Two previously unknown (disconformity-bounded?) units were intercepted below the Cape Fear. The deepest (172.8–168.9 m) is an unnamed, possibly Cenomanian, light gray, non-marine flood plain deposit. This is overlain at 168.9 m by a complex, unnamed marine unit (lower Coniacian?) that includes dark gray, tidally bedded (wavy, flaser, lenticular bedding) to burrowed sands and muds with lignite.

At 128.5 m, the upper Coniacian/lower Santonian Cape Fear overlies the unnamed marine unit. The Cape Fear includes non-marine flood plain deposits. It is overlain by the middle Santonian to upper Campanian Tar Heel at 107.4 m. The Tar Heel here is thick (82.8 m) and includes marine to estuarine facies sequences (cross bedded lignitic sands, lenticularly bedded lignitic mud, tidally bedded green sands and muds) and internal discontinuities (e.g., lime-cemented hardgrounds? at 56.8 m and 70.1 m). The upper Campanian Bladen, which disconformably overlies the Tar Heel at 26.7 m, includes black lenticularly bedded mud and gray quartz sand with lignitic flasers.

The USGS is currently coring to basement at this site and resampling selected intervals for nannofossils.