28 Interstate Stratigraphic Correlation: A Practical Geology Session (Posters)

Primarily a hands-on display of core and samples with posters, and talks, to facilitate interstate correlation. Concepts covered are related to interstate correlation problems in stratigraphy—mapping, source rocks for REE minerals, geochronology, and regolith.

Tuesday, 10 March 2026
9:00 AM - 5:00 PM
RCC, Lower Level Hall

A Regional Synthesis of Aminostratigraphic Results for Quaternary Units from Coastal Plain Onshore, Barrier Island, and Offshore Collections of North and South Carolina, USA

Paper number: 28-0
Program: Technical Sessions
Time: 9:00 AM – 9:15 AM

Authors

Abstract

Over the past 10 years, amino acid racemization (AAR) analyses on more than 500 Quaternary mollusks (primarily Mercenaria and Mulinia) from 100+ sites (exposures, barrier island or offshore cores) were used to develop a regional aminostratigraphic framework for correlation and age estimation for  Coastal Plain units of North and South Carolina.  Most of these collections have prior AAR results obtained using ion-exchange (IEx) or gas chromatographic (GC) methods. The current effort is to build a database using the more sensitive and rapid reverse-phase (RP) analytical method available at Northern Arizona University (NAU) to facilitate onshore-offshore comparison and eliminate inter-method differences. Analyzed sites include sediment cores from the Albemarle Embayment (n~30: Wehmiller et al., 2010), offshore cores (Onslow Bay and Georgia Bight) from the 2015 BOEM ASAP program (n= ~20: Long et al., 2021; Conery et al., 2021), offshore cores from the ongoing BOEM Long Bay Cooperative Project (n = ~ 25; Luciano et al., 2025), and NC-SC onshore cores or exposures  for the continuing USGS Interstate Correlation Project (n = ~30; Doar et al., 2025). Results for beach shells and offshore grab samples supplement the dataset and relate offshore and onshore units. Broadly-defined regional aminozones are recognized and represent early, middle, and late Pleistocene intervals, each subdivided if sufficient quality samples are available. Consistency of AAR results with stratigraphic superposition or latitude (temperature) trends, as well as precision of multiple analyses, are useful criteria for data evaluation. Age mixing is inferred from both outcrop and offshore core results if scatter in D/L values is unusually large (~10% or greater), confirming the importance of conducting multiple analyses of multiple taxa where possible. Age calibration is available for a limited number of sites, based primarily on direct or indirect association with U-series coral ages. Correlation of aminozones to OSL-dated units is possible in selected cases. Paired AAR-radiocarbon analyses on individual shells provide additional age constraints. Although radiocarbon results for Pleistocene shells are often interpreted as minimum ages, some AAR results may be consistent with ~50 ka age estimates, depending on optional age/temperature modeling of AAR kinetics. Results will contribute to a more detailed understanding of the preserved (and debated) sea-level records of the late Pleistocene (MIS 5 and MIS 3: Mallinson et al., 2025).

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411561

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