COMPOUND-SPECIFIC RADIOCARBON, STABLE CARBON ISOTOPE AND BIOMARKER ANALYSIS OF MIXED MARINE/TERRESTRIAL LIPIDS PRESERVED IN ARCHAEOLOGICAL POTTERY VESSELS
Emmanuelle Casanova, Timothy Knowles, Candice Ford, Lucy Cramp, Niall Sharples, Richard P. Evershed
Abstract
ABSTRACT At archaeological sites located on islands or near the coast, the potential exists for lipid extracts of potsherds to contain fatty acids (FA) from both aquatic and terrestrial organisms, meaning that consideration must be given to marine reservoir effects (MRE) in radiocarbon ( 14 C) analyses. Here we studied the site of Bornais (Outer Hebrides, UK) where a local MRE, ΔR of –65 ± 45 yr was determined through the paired 14 C determinations of terrestrial and marine faunal bones. Lipid analysis of 49 potsherds, revealed aquatic biomarkers in 45% of the vessels, and δ 13 C values of C 16:0 and C 18:0 FAs revealed ruminant and marine product mixing for 71% of the vessels. Compound-specific 14 C analysis (CSRA) of FAs yielded intermediate 14 C ages between those of terrestrial and marine bones from the same contexts, confirming an MRE existed. A database containing δ 13 C values for FAs from reference terrestrial and marine organisms provided endmembers for calculating the percentage marine-derived C ( % marine ) in FAs. We show that lipid 14 C dates can be corrected using determined % marine and ΔR values, such that pottery vessels from coastal locations can be 14 C dated by CSRA of FAs.