NEW INSIGHTS INTO THE LATE PLEISTOCENE STRATIGRAPHY AND PALEOENVIRONMENTS OF EASTERN NORTH CAROLINA, USA

The late Pleistocene (ca. 130 ka to 11.7 ka) stratigraphy of the northeastern North Carolina coastal plain is being investigated to provide insights into future coastal evolution. Stratigraphic sequences and facies are being mapped using CHIRP seismic data, ground penetrating radar data, and core data (lithofacies, sedimentology, microfossils, palynology). The chronostratigraphic framework is provided by optically stimulated luminescence ages and, for Holocene samples, radiocarbon ages. Lithofacies corresponding to a variety of coastal depositional environments are being mapped regionally, within the context of the sequence stratigraphic framework, to understand how the system evolved during late Pleistocene episodes of relative sea-level change. Hydrodynamic models are being developed and calibrated using the geological data to understand the changes to currents and wave energy that occurred as the system was inundated. The westward extent of the late Pleistocene shoreline is marked by the Suffolk Shoreline (a.k.a., the Suffolk Scarp), a MIS 5 highstand prism located up to 120 km inland from the modern ocean shoreline. Multiple late Pleistocene lowstand, transgressive, and highstand deposits occur seaward of the paleoshoreline, on the coastal plain and beneath the modern estuaries, and occur above the MIS 6 subaerial unconformity. These deposits contain a record of paleoenvironmental and morphodynamic conditions occurring during rapid rise and highstand that provide an analog for future conditions. Notably, tidalite facies (wavy, lenticular and flaser beds, inclined heterolithic strata, etc.) are widespread within transgressive and some highstand deposits, indicating a significantly greater tidal regime than that which exists today. MIS5 facies occur in all areas and include inclined heterolithic strata (within channel-fill), shoreface sands, and open shelf facies. In the northern part of the study area, sand-rich fluvial braidplain facies, tidal facies and barrier-island facies dating to MIS3 occur as a result of glacio-isostatic relaxation of this region at the time of deposition.