NOAA/WDS Paleoclimatology - Dare County, North Carolina Quaternary Subsurface Aminostratigraphy

Amino acid enantiomeric ratio data are presented for Pleistocene mollusks obtained from a suite of split-spoon and vibracore samples at sites in Dare County, northeastern North Carolina. The region lies within the Albemarle Embayment, a thick sequence of Quaternary and pre-Quaternary strata in the mid-Atlantic coastal plain, eastern United States. Land surface elevations range from 0 to +2 m. Sample depths range from ~ 4 meters to ~ 35 m below mean sea level. Specimens of the bivalve mollusk Mulinia and Mercenaria have been analyzed by ion-exchange and gas chromatography. Aminozones representing clusters of D/L values are used to correlate depositional sequences in the study area and to estimate times of deposition based on kinetic modeling of amino acid racemization. Deepest units are estimated to be older than 1 million years, while the shallowest Pleistocene units are estimated to be last interglacial (~80,000 - 125,000 yrs) in age, based on both racemization and uranium-thorium age estimates.