Paper No. 139-7
Presentation Time: 9:50 AM
MULTI-PROXY CONSTRAINTS ON MARINE ISOTOPE STAGE 5E SEA-LEVEL POSITION IN THE U.S. ATLANTIC COASTAL PLAIN: IMPLICATIONS FOR GLACIO-ISOSTATIC ADJUSTMENT AND SEA-LEVEL MODELING
The U.S. Atlantic Coastal Plain (ACP) preserves a number of marine terraces associated with paleo-shoreline escarpments that record various Quaternary sea-level highstands. One of the most widely studied periods of the late Quaternary is Marine Isotope Stage (MIS) 5e (~125-115 ka), which is the most recent period where significant ice-mass loss likely occurred from the Greenland and Antarctic Ice Sheets. As such, MIS 5e provides insights relevant to future sea-level rise. Constraining local, relative sea level (RSL) for different regions compared to globally averaged eustatic sea level is extremely important for predicting the complex patterns of sea-level rise we can expect in the future. Recent work has yielded closed-system U-Th coral ages corresponding with MIS 5e from the southern ACP in South Carolina and Florida (RSL 7-8m above present), providing the first confirmed RSL estimates from north of the Florida Keys for that time period. In contrast, RSL during MIS 5e farther north in the mid-ACP is largely unconstrained, with no surficial deposits dated to MIS 5e. Instead, MIS 5a (~80-75 ka) deposits are prevalent, reaching similar elevations as the MIS 5e deposits to the south. The lack of MIS 5e-dated deposits and the prevalence of MIS 5a-dated deposits at 7-8 m elevations has been attributed to the post-glacial subsidence of the pro-glacial forebulge (glacio-isostatic adjustment – GIA), centered in the region between New Jersey and the Delmarva Peninsula. However, GIA models cannot yet constrain RSL during the Holocene (~11.7-0 ka) or MIS 5e in the peripheral region of the pro-glacial forebulge of the mid-ACP. We present multi-proxy datasets (stratigraphy, lithology, micro-paleontology, stable isotope geochemistry) providing new RSL constraints for MIS 5e from multiple sites in the mid-ACP near the mouth of the Chesapeake Bay, which can ultimately be used to improve estimates of GIA and ice-mass loss contributions in future studies.