Strontium isotope ratios (87Sr/86Sr) are a powerful geochemical tracer and are used in a wide range of fields including Archaeology, Forensic sciences, Palaeontology, Ecology, Soil and Food sciences. These applications are based on the principal that the strontium isotope ratios of a certain material will reflect the sources of strontium, which were available during its formation.
The IRHUM (isotopic reconstruction of human migration) database provides a reference of bioavailable strontium isotope ratios for France. It requires the Google Earth API to run and can be found at -> www.rses.anu.edu.au/research-areas/archaeogeochemistry.
The aim of the database is to allow easy access to our data and to provide spatial context for each sample. The current dataset contains 400 sample locations covering the major geologic units of the Paris and Aquitaine Basin, the Massif Central, and the Pyrenees. At each site rock, soil, and plant samples have been collected. The samples were analysed at the Environmental Geochemistry and Geochronology Laboratory at RSES using a Neptune Multicollector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS). New results will be added to the database continuously with the aim of creating a reference map covering all major geologic units of France within the next 2 years.
Strontium isotopes as tool to investigate ancient human migrations
Humans and animals incorporate strontium from their diet into their bones and teeth. Tooth enamel contains strontium isotope signatures acquired during childhood and is most resistant to weathering and overprinting. The strontium isotope signature in bones on the other hand will reflect the average isotopic composition over the last ~10 years of the organism’s life, due to the continuous biological remodelling of the bones. Thus, measuring the isotope ratios of human skeletal remains and comparing them to a strontium isotope reference map of the environment enables us to reconstruct human mobility across geologically different terrains.