LATE QUATERNARY SEA-LEVEL HIGHSTANDS OF THE MID-ATLANTIC US COASTAL PLAIN AND SUB-ORBITAL VARIABILITY WITH IMPLICATIONS FOR ICE SHEET SENSITIVITY

Emerged Quaternary paleo-shorelines and marine deposits provide a more direct way to reconstruct and analyze the magnitude of relative sea-level (RSL) variability than methods using oxygen isotope analyses of deep ocean benthic foraminifera. Building on established lithostratigraphy and a newly revised uranium-series chronology for the coastal marine deposits of Virginia, we reconstruct sea-level variability over the last three interglacial periods by interpreting foraminiferal and ostracode faunal assemblages, pollen floral assemblages, the ratio of pollen to dinoflagellate cyst abundances (relative distance from shore indicator), and stable isotope records. Results allow us to correlate the Tabb Formation and Rappahannock River Beds from the Coastal Plain with the Nassawadox and Omar Formations from the Delmarva Peninsula of Virginia, respectively. Furthermore, they also establish sub-orbital sea level variability during Marine Isotope Stages 5, 7, and/or 9. After correcting our RSL curve for vertical displacement due to glacio-isostasy, we correlated these marine units to others of corresponding ages from North Carolina, South Carolina, Georgia, and Florida. Combining our results with recent sea-level fingerprinting studies that predict various ice sheet melt scenarios, we conclude that the abundance and distribution of emerged Quaternary marine deposits and corresponding paleo-shorelines suggests that a relatively unstable West Antarctic Ice Sheet likely contributed to the interglacial RSL highstands along the US Atlantic Coastal Plain.