LATE CRETACEOUS DEPOSITIONAL SEQUENCES AND SEA LEVEL HISTORY OF THE NORTH CAROLINA COASTAL PLAIN

In middle to outer neritic environments, differentiation between unconformities that develop due to relative base level rise versus fall can be problematic. Analyses of corehole lithofacies, in correlation with 87Sr/86Sr data and biostratigraphy, provide a framework for understanding sea-level history in North Carolina during the Late Cretaceous. Six depositional sequences (four Campanian and two Maastrichtian) are identified and sedimentation rates are calculated. Comparison between North Carolina and New Jersey sequences show: 1) The basal boundary of the Tar Heel I sequence is correlative with the basal New Jersey Merchantville II boundary and formed by a relative lowering of base level; 2) the boundary between Tar Heel I and Tar Heel II is correlative with the Merchantville III/Englishtown sequence boundary and most likely resulted from relative base level lowering; 3) the Donoho Creek I and Donoho Creek II sequences are very thin and the boundary between them does not correspond to a sequence boundary in New Jersey, suggesting that it may represent a local maximum flooding surface; 4) the basal Peedee I boundary is a major disconformity that is correlative with the base of the Navesink I sequence in New Jersey and represents relative base level lowering; 5) the basal Peedee II boundary is correlative with the basal Navesink II boundary and represents relative base level lowering. Increased sedimentation rates for the Tar Heel II, Peedee I and Peedee II sequences, which are significantly higher than rates recorded from equivalent units in New Jersey for the late Maastrichtian, suggest that proximity to a sediment source coupled with relatively higher uplift of the southern Appalachians affected sediment supply to the shelf in this region.