Trace Elements in Archaeological Shells: Limits and Potential for Seasonality and Paleoclimate Studies

Summary

Stable oxygen isotope analysis of marine shells has increasingly become a common tool used to identify seasonality and reconstruct past sea surface temperatures (PSST). Oxygen isotope analysis of marine carbonates cannot, however, discriminate between freshwater fluxes and temperature changes as they both affect oxygen isotope ratios (18O/16O). The inability to discriminate the geochemical data can lead to ambiguous PSST and seasonality interpretations. Trace element ratios of Sr/Ca are affected in marine organisms by salinity and freshwater, whereas Mg/Ca ratios are specifically affected by temperature. Trace element ratios can potentially be used to isolate freshwater and temperature changes, and provide more reliable PSST estimates for sites located in estuarine settings or in areas with high seasonal freshwater discharge. For this project we used live-collected shells to examine geochemical properties of Saxidomus gigantea (butter clam), one of the most commonly recovered bivalves from shell middens on the Pacific Northwest Coast to test the limits and potential of trace element analysis to resolve archaeological questions of seasonality and past sea surface temperatures.

This Resource is Part of the Following Collections

• Society for American Archaeology 81st Annual Meeting, Orlando, FL (2016)

Keywords

Spatial Coverage