ACCELERATE aimed to 1) develop a rapid and affordable technique to analyse palaeoclimatic information preserved in the elemental composition of shell carbonates; and 2) establish standardised ways of applying these techniques to large samples of marine molluscs from coastal shell-midden deposits around the world in order to reconstruct climate change, seasonality of shell collection, and rates of accumulation of shell-midden deposits.
Shell-midden deposits occur in their hundreds of thousands around the world’s coastlines. Many are mounds of massive size (>1000–50,000 m3). They represent the long-term accumulation of food debris at the settlements and camping sites of former coastal peoples, in which the discarded shells of marine molluscs are the dominant constituent. They afford a global, long-term archive extending over thousands of years of environmental change.
However, a major limitation with existing approaches is the need for large samples (an individual shell midden may contain millions of shells) and the high cost of the currentlyavailable techniques. The most commonly used tools are Isotope-Ratio Mass Spectrometry (IRMS) and Inductively Coupled Plasma Mass Spectrometry (ICPMS) which can provide precise information about the composition of carbonate. However, these analyses suffer from time consuming sample preparation and high processing costs per sample (~15€), restricting application to small datasets, typically tens or at most hundreds of shells. This is a huge discrepancy, as shell bearing sites can be found throughout the period of human coastal exploitation (110ka -today) and on most coastlines across the world.
Laser Induced Breakdown Spectroscopy (LIBS) offers the potential to quickly and cheaply analyse the elemental composition of shell carbonate. The use of the method for organic carbonate from shells is still in its infancy and only recently have successful results been published . Exploring the research potential of the technique, finding its restrictions and developing a cost-effective methodology for the mass production of climatic records is a priority to unlock the full potential of palaeo-environmental data stored within shell midden deposits.
ACCELERATE developed LIBS to address questions at the cutting edge of both the fields of environmental reconstruction and archaeology. Prof. Demetrios Anglos is part of an internationally renowned research facility the Foundation for Research and Technology - Hellas (FORTH), Greece, undertaking research that combines laser technology and conservation studies.