Paper No. 7
Presentation Time: 9:00 AM-6:00 PM
CRETACEOUS GEOLOGY OF THE CAPE FEAR RIVER VALLEY (PART A): FROM ROCKFISH CREEK TO MILEPOST 63.2, NORTH CAROLINA
The Cretaceous geology of the Cape Fear River valley has been a topic of interest to coastal plain geologists since the early 1900’s. Recent drilling and outcrop studies by the U.S. Geological Survey have provided a wealth of new data that allows for better correlation of Cretaceous sediments from the subsurface to the outcrops in the North Carolina Coastal Plain. For this study, 34 outcrops along the Cape Fear River were examined for stratification, grain-size, mineralogy, and fossil content. Elevation above mean sea level was used as a reference point for measured sections, and radiometric profiles were acquired. Marine versus terrestrial palynomorph ratios were calculated for all outcrops to infer fluvial, estuarine and delta-front depositional environments. Palynomorph and calcareous nannofossil zones were determined where possible. Ten outcrops show representative sections of the geologic formations exposed along the up-dip part of the Cape Fear River Valley. Many of these exposures contain unconformable contacts that are traceable across the North and South Carolina Coastal Plain. Most of these outcrops have Cretaceous sediments overlain by Cenozoic alluvium.
The outcrops and their formations, ages, and pollen zones are as follows, from up-dip to down-dip: 1) Rockfish Creek--Coniacian to Santonian, Cape Fear Formation, Sohlipollis Zone. 2) Milepost 100.5-- contact between the Cape Fear Formation and the upper Santonian Shepherd Grove Formation, which is assigned to the Osculapollis vestibulus (Ov) Zone. 3,4,5) Tolar, Prospect Hall, and Johnson’s Landings, -- upper Santonian and lower Campanian Caddin Formation, Ov pollen Zone. 6,7,8,9) Council Island, Tar Heel, Dawson’s, and Dixon’s Landings-- lower to middle Campanian Cane Acre Formation, Holleopollenites propinquus (Hp) Zone. 10) Milepost 63.2-- middle Campanian Bladen Formation, Complexiopollis abditus (Ca) Zone. 10,11) Between milepost 63.2 and Walkers Bluff--middle Campanian Coachman Formation, Holkopollenites forix (Hf) Zone. These unconformity-bounded formations record several Late Cretaceous sea level fluctuations.