This abstracts is part of session #378:
Title:
How to construct a relevant baseline of bioavailable 87Sr/86Sr? Testing different approaches to constrain mobility in Bronze Age Greece.
Content:
Sr isotopes have provided us with unprecedented insights into past human mobility, but their interpretation can drastically change based on the applied reference baseline of bioavailable 87Sr/86Sr. At present, no consensus exists on the methods and materials applied to establish these baselines. A recent multi-proxy baseline of Greece has shown that despite a heterogeneous geological background the bioavailable Sr isotopic range is rather narrow. This complicates the identification of ancient mobility within Greece, as overlapping baseline ranges from different regions can mask the presence of mobility. Here, we present a large Sr isotope dataset of ancient human remains from Greece, consisting of 260 Bronze Age individuals from ten archaeological sites, and test the results within regional and site-specific 87Sr/86Sr baselines. The regional baselines constrain bioavailable 87Sr/86Sr based on 1) the municipality and 2) surface lithology of the sites, while the site-specific baselines were defined using human 87Sr/86Sr values of 1) the entire population and 2) children of the sites. The investigated individuals are characterised by a narrow range in 87Sr/86Sr (0.70822-0.7105), resulting in significant overlap and similar average human 87Sr/86Sr values for all sites. While the municipal baselines identify only two non-local individuals at two sites, the surface lithological baselines flag six individuals from three different sites as non-local. At five sites, a total of seven non-locals were identified using the 87Sr/86Sr values of their population, of which only three were grouped as non-local by the surface lithological baselines. Finally, the 87Sr/86Sr values of the children identify potential mobility at every site with sufficient individuals, suggesting a more transient population. The different number of non-locals identified by the different baseline approaches reveal the limitations of Sr isotopes in regards to identifying mobility in regions characterised by isotopically narrow ranges, emphasising the need for caution when interpreting Sr data.
Keywords:
Sr isotopes, Sr baseline, Mobility, Bronze Age, Greece
Main authors:
Anja Frank3,9
Co-author:
Moutafi Ioanna1,5
Nicholas Herrmann4
Lagia Anna7
Robert Frei6
Kristian Kristiansen2,8
Karin Frei3
Affiliations:
1 American School of Classical Studies at Athens
2 GLOBE Institute
3 National Museum of Denmark
4 Texas State University
5 University of Cambridge
6 University of Copenhagen
7 University of Freiburg
8 University of Gothenburg
9 University of Hamburg
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