HR: 0800h
AN: V41F-1530    [Abstracts]
TI: Geochemistry Meets Anthropology: the use of Sr Isotopes as Tracers for Ancient Human Migration.
AU: * Solis, G
EM: gsolis@geofisica.unam.mx
AF: LUGIS, Instituto de Geofisica, UNAM, Cd. Universitaria, Mexico City, 04510 Mexico
AU: Schaaf, P
EM: pschaaf@geofisica.unam.mx
AF: LUGIS, Instituto de Geofisica, UNAM, Cd. Universitaria, Mexico City, 04510 Mexico
AU: Hernandez, T
EM: tht@geofisica.unam.mx
AF: LUGIS, Instituto de Geofisica, UNAM, Cd. Universitaria, Mexico City, 04510 Mexico
AU: Horn, P
EM: horn@min.uni-muenchen.de
AF: Department of Geosciences, University of Munich, Theresienstr. 42, Munich, 80333 Germany
AU: Manzanilla, L
EM: lmanza@servidor.unam.mx
AF: Instituto de Investigaciones Antropologicas, UNAM, Cd. Universitaria, Mexico City, 04510 Mexico
AB: Sr isotopes have increasingly become an important tool in archeology and anthropology in determining provenance of humans. By comparing isotopic signatures of human teeth and bone with the soil environment, Sr isotope ratios have been used as tracers identifying living areas. Sr isotope ratios in tooth enamel reflect the source of diet during youth, whereas ratios in dentine and bones come from the food growing in local geologies around the time of death. However, since analytical procedures vary from lab to lab we present here our new technique and how it affects results. We studied 11 teeth and 12 bone samples from the archeological site of Teotihuacan, central Mexico, as well as soil and water from the locality. Mechanical sample preparation of all teeth involved isolation of the enamel layer with the aid of an orthodontical micro-tool. For some enamel samples up to three fractions (two leachates and residue) were obtained for measurement. Thoroughly cleaned bone material underwent no leaching. As an example, 87Sr/86Sr results from a sample with ratios of 0.70477 for bone (which is identical to highland soil), 0.70530 for first leachate, 0.70590 for second leachate, and 0.70668 (mean accuracy +/- 0.00004) for enamel, clearly show enamel contamination by mobile Sr probably from soil. We thus find that repeated cleaning and particularly repeated leaching procedures, including isotopic measurement of the leachates, are critical to differentiate primary from secondary Sr isotope ratios as product of interaction of soil, sediments and water from the substrate where burials took place.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1040 Radiogenic isotope geochemistry
DE: 1094 Instruments and techniques
DE: 8486 Field relationships (1090, 3690)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005