Marine reservoir corrections for the Caribbean demonstrate high intra- and inter-island variability in local reservoir offsets

Abstract

The abundance of marine mollusks found in Pre-Columbian archaeological sites in the Caribbean has made them enticing sample types for radiocarbon dating. Unfortunately, a paucity of local marine reservoir corrections (ΔR) for most of the region limits building chronologies using marine-based carbonates. Here we present a suite of 33 new ΔR values for 22 islands in both the Greater and Lesser Antilles derived from known-age shells pre-dating A.D. 1950 (i.e., pre-atomic testing) and is the first intensive radiocarbon dating effort in the region to examine ΔR effects. The spatial coverage and corrections presented here demonstrate wide variation within and between islands across the Antilles, Bahamian archipelago, and islands that skirt the coast of northern South America. Correction values range from 282 ± 24 yr in Grenada to −547 ± 36 yr in Anegada. Calibration of published radiocarbon dates on archaeological marine shell using these new ΔR values demonstrates the need for caution when dating marine shell in the Caribbean, but illustrates the potential for these corrections to provide more accurate radiocarbon chronologies. Research is now focused on identifying the causal mechanisms behind the high variability in Caribbean ΔR and the implications these data have for refining radiocarbon sequences in the region, particularly for islands where there are currently no ΔR values.