55 Sea-Level History from the U.S. East Coast—Insights for Projecting Future Change

Sunday, 19 March 2023
1:30 PM - 3:15 PM
Regency Ballroom B

URANIUM SERIES DATING OF QUATERNARY CORALS FROM THE SOUTHEASTERN U.S. ATLANTIC COASTAL PLAIN YIELDS INSIGHT FOR RECONSTRUCTING RELATIVE SEA LEVEL OVER THE LAST FULL GLACIAL CYCLE

Paper number: 55-5
Program: Symposia
Time: 2:35 PM – 2:55 PM

Authors

Abstract

We discuss an extensive Uranium-series (U-Th) dataset (Poirier et al., in review) that provides comprehensive insights into local, relative sea-level (RSL) history of the southeastern U.S. Atlantic Coastal Plain (ACP) during Quaternary high-stand events. The dataset includes 71 new U-Th analyses, in addition to 98 published coral dates that have been re-evaluated. The dated fossil corals were collected from marine deposits in outcrop, as well as from boreholes and excavations from sites between Virginia and Florida. Closed-system U-Th coral dates align with sea-level highstand events during early Marine Isotope Stage (MIS) 3, MIS 5a, MIS 5c, and MIS 5e. Importantly, the new closed-system results corresponding with the early MIS 3, MIS 5c, and MIS 5e represent the first robust U-Th coral ages from units north of the Florida Keys for those time periods. Additionally, we document an apparent ~10 kyr offset in the closed-system ages of deposits dated to MIS 5a in the northern study region of the Norfolk Arch to Albemarle Embayment region of Virginia and North Carolina (average = 74.0 ± 4.9 ka [2σ], n=13) relative to those from the southeast Georgia Embayment of South Carolina and Georgia (average = 84.0 ± 4.6 ka [2σ], n=9) and the corresponding paleo-reef tract in the Florida Keys (average = 84.7 ± 4.7 ka [2σ], n=9). Various new insights derived from refining the ages of these marine deposits and their associated paleoshorelines provide the opportunity to compare the regional RSL signals to global estimates for sea-level over the last glacial cycle with implications for long-term impacts of subsidence related to glacio-isostatic adjustment.

Geological Society of America Abstracts with Programs. Vol. 55, No. 2

doi: 10.1130/abs/2023SE-385252

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