A novel mean-value-based approach for correcting radiocarbon age anomalies in terrestrial gastropods: Insights from the Tibetan Plateau

Abstract

Terrestrial gastropod shells are abundant in loess deposits and represent a promising alternative material for radiocarbon dating. However, accurately correcting radiocarbon age anomalies caused by the limestone effect in shells remains a critical challenge. In this study, we report new radiocarbon ages of gastropod shells and charcoals from two loess sequences on the Tibetan Plateau. Cathaica rossimontana exhibits a mean offset of 1788 ± 240 years, while Vollonia tenera shows an average age anomaly of 997 ± 227 years. By integrating stratigraphic and modern surveys, we demonstrate that the same species gastropods under stable environments exhibit a concentrated limestone effect with a low coefficient of variation (0.10–0.22). Based on this theoretical foundation, we propose a novel correction method for age anomalies using linear regression modeling and average limestone effect. The corrected radiocarbon ages of gastropod shells show excellent agreement with reliable charcoal ages in the BST and GG loess sections, validating the reliability and robustness of the proposed method. Compared to conventional modern-value correction approach, the mean - value correction method offers significant advantages, including broader applicability and greater reliability. These findings advance the potential of gastropod shells as reliable chronological markers in Quaternary loess research.