QUATERNARY EVOLUTION OF NORTHEASTERN NORTH CAROLINA'S COASTAL SYSTEM AND ADJACENT UPLAND (Invited Presentation)

The Quaternary stratigraphic framework has been defined for northeastern North Carolina’s coastal system using ca. 3000 km of high-resolution boomer and chirp seismic data, >100 km of ground penetrating radar data, >100 vibracores and 28 rotasonic cores. Chronostratigraphic control is provided by amino acid racemization, strontium-isotopes, radiocarbon, and optically stimulated luminescence data. Paleoenvironments are defined using lithofacies and microfossils. These data enable an understanding of the role of antecedent geology, global sea-level fluctuations, fluvial processes, and isostasy on the development of this modern coastal system. Seven depositional sequences and associated systems tracts are defined beneath the Pamlico and Albemarle Sounds and adjacent upland. Lower Quaternary sequences fill the regional Albemarle Embayment and exhibit a wide range of environments including shelf sand bodies and shoreface clinoforms. A prominent regional unconformity and amalgamated ravinement surface marks the transition between the middle and upper Quaternary sequences and represents an increase in the magnitude and period of sea-level oscillations and isostatic effects. Middle to upper Quaternary sequences are characterized by greater degrees of fluvial incision and inner shelf to estuarine facies. Upper Quaternary sequences are laterally correlative onshore to stranded paleoshoreline units and associated estuarine and inner shelf lithosomes, and date to MIS5 and MIS3 (ca. 125 ka to 50 ka), although MIS3 ages are controversial. The modern expression of antecedent controls includes the position of Cape Hatteras, the location of various modern inlets, and paleodrainage characteristics which further control the modern Pamlico Sound bathymetry. Comparison of late Quaternary sea-level indicators from paleoshoreline and tidal deposits, with far-field indicators and proxy data published by other workers suggests that isostatic mechanisms may have played a significant role in the evolution of this system since the middle Quaternary.