Accounting for the marine reservoir effect in radiocarbon calibration

The radiocarbon dating method is supported by highly refined calibration data empirically obtained from environmental archives. Nevertheless, marine calibration remains problematic due to the spatiotemporally variable Marine Reservoir Effect (MRE). The currently accepted curve for radiocarbon calibration in the ocean is a global curve, partly derived by numerical modelling from its atmospheric counterpart. As such, this curve cannot account for the effects of local phenomena, strongly correlated with C-14 signatures in seawater (e.g., ocean dynamics and continental input). Although the radiocarbon community has suggested the use of regional calibration curves that would better represent the heterogeneous ocean reservoir, a reasonable method for their construction has not yet been proposed. We directly address this longstanding issue in radiocarbon research by exploring the output of a model for the temporal evolution of the MRE. The limitations of this model are inherited by our method, and this hinders the use of the regional curves derived here in many regions of the world ocean. Nevertheless, the approach described in this paper remains valid regardless of the chosen model and our preliminary results show that, with the future development of accurate and highly resolved models for the MRE, this method may be a promising alternative to the use of Delta R values in the process of marine calibration. (C) 2019 Elsevier Ltd. All rights reserved.