164 Advances and Applications of Geochemistry in Archaeology
Geochemistry has broad applications in archaeology. This session’s goal is to stimulate collaborations between archaeologists and technical experts. Techniques and applications of interest include, but are not limited to, provenance, paleoenvironmental reconstruction, site formation, diet, subsistence, and age-dating.
Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 214D
Radiocarbon Dating Mollusk Shells: Challenges, Advances, and Best Practices
Paper number: 164-1
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM
Authors
Abstract
Radiocarbon dating is a critical tool for establishing site chronologies and reconstructing formation processes at archaeological sites worldwide. However, directly dating mollusk shells (marine, freshwater, or terrestrial) presents persistent challenges due to significant and variable radiocarbon age offsets. These offsets stem from a range of factors that introduce "old" carbon into shell carbonates, ranging in scale from localized or species-specific effects to regional trends. This presentation examines the causes and consequences of these offsets, drawing on case studies from North America. We explore the “good, the bad, and the ugly” of shell dating, clarify common misconceptions, and offer practical guidance for archaeologists and geoscientists working with these materials. We also highlight recent methodological advances such as improved pretreatment protocols, compound-specific dating techniques, refined regional correction factors (ΔR), and emerging statistical approaches that are improving the accuracy and interpretive power of shell-based chronologies. Still, the reliability of shell dates is highly contingent on contextual data, including species ecology, depositional setting, hydrology, and local geology. Despite the challenges, mollusk shells remain a valuable and often necessary resource for constructing robust chronological frameworks, particularly where organic materials are poorly preserved. When approached critically and with contextual awareness, shell radiocarbon dates can meaningfully inform archaeological and paleoenvironmental narratives across diverse landscapes.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-412057
© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.