T282 Response of Coastal Environments to Accelerated Sea Level Rise

Wednesday, 8 October 2008
8:00 AM - 12:00 PM

Stratigraphy and Evolutionary Development of Late Quaternary Deposits, Northeastern North Carolina and Southeastern Virginia

Paper number: T282-1
Program: Technical Sessions
Time: 8:15 AM – 8:30 AM

Authors

Abstract

The north-south trending Suffolk Shoreline (SS) is the product of several sea-level highstands that occurred during MIS 5. LiDAR imagery reveals that the feature is split into two roughly parallel sand ridges in some areas. Corresponding highstand facies occur in the subsurface to the east as marine deposits and extend up drainages to the west as estuarine deposits. Ravinement and other erosional processes modified or removed portions of deposits laid down by previous sea-level cycles so that only the deposits of the last sea-level event to occupy the SS are preserved relatively intact. This study characterizes SS deposits and correlates them with coeval facies in the subsurface using extensive core-hole data, ground penetrating radar, and a combination of optically stimulated luminescence, U-series, and amino-acid racemization dating methods. Core-hole transects were made across the SS on the Pamlico/Neuse, Albemarle/Pamlico, and James/Albemarle Peninsulas, northeastern North Carolina and southeastern Virginia. Most cores terminate in the Pliocene Yorktown Formation.

Lithologic analysis indicates that depositional sequences are bounded by soil profiles and typically grade up-section from wood and plant detritus-rich, muddy swamp-forest deposits to laminated mud and sand estuarine deposits to mollusk shell-rich, marine muddy sand. OSL data indicate that the SS consists of imbricated sandy deposits that represent highstand shoreline complexes of MIS 5e, 5c, and 5a. East of the SS, age data indicate that the late Quaternary section is dominated by deposits associated with MIS 5a and MIS 3. MIS 5a marine deposits are very shelly and occur as a seaward thickening wedge below approximately 5 m bMSL. These deposits are overlain by a sequence dominated by laminated mud and interpreted to represent low-brackish estuarine deposition. OSL data indicate that these latter deposits were laid down during MIS 3 and correlate with paleo-shoreline deposits on the Currituck Peninsula and Roanoke Island.