DEFINING THE RESPONSE OF A LOW GRADIENT COASTAL SYSTEM TO RAPID SEA-LEVEL CHANGE DURING THE LATE PLEISTOCENE

The late Pleistocene stratigraphy of eastern North Carolina is characterized by coastal and inner shelf deposits that formed in response to high rates of sea-level rise during Marine Isotope Stage 5 (MIS 5; 130 to 71 ka) and Marine Isotope Stage 3 (MIS 3; 55 to 29 ka). The characteristics (i.e., stratigraphy, sedimentology, areal extent, microfossils content, chronology) of these deposits are being defined to determine the evolution of this low-gradient coastal system in response to sea-level changes. The MIS 3 and MIS 5 shorelines have been previously investigated in eastern North Carolina. However, there are some areas where few or no data have been collected, making it difficult to assess the areal extent of facies and corresponding depositional environments. To overcome these limitations and more fully understand the spatial and temporal evolution of coastal depositional environments in response to rapid sea-level changes, geophysical and geological data from the Pamlico River area (Beaufort and Hyde Counties, NC) were collected and analyzed. Approximately 170 km of high resolution seismic (chirp) data were collected in the Pamlico River. These data reveal seismic stratigraphic units with distinctive facies likely corresponding to MIS 5 and MIS 3 coastal to inner shelf deposits. To complement the seismic data, approximately 11 km of ground penetrating radar (GPR) data were acquired on land, and 11 cores were acquired in terrestrial and estuarine areas. Paleoenvironmental conditions are being determined from cores based on the characteristics of biofacies and lithofacies. The regional extent of stratigraphic units and lithofacies is being mapped by correlating lithofacies to the chirp and GPR data. Optically stimulated luminescence dating is being used to provide the chronological framework. By studying the morphology and paleoenvironmental changes and the processes that shaped this coastal system in the past, we can make reasonable forecasts of what this coastline might look like in the near future as a result of accelerated rates of sea-level rise.