Lead isotopic composition by Thermal Ionization Mass Spectrometry for provenance studies in Archaeology

BAVIO, MARTA; FERNÁNDEZ, MAURICIO; ZUBILLAGA, ERICA N.; CIARLO, NICOLÁS C.; GELI MAURI, RUT; GAUTIER, EDUARDO

Mendoza

Simposio; 15th Rio Symposium on Atomic Spectrometry; 2019

Universidad Nacional de Cuyo

Thermal Ionization Mass Spectrometry (TIMS) is an inorganic mass spectrometry technique with high precision and accuracy applied mainly in the field of geology, archeology and nuclear industry. In this work, Lead Isotopic Composition analysis was performed in 7 samples of anchor stocks, recovered from the Catalonian coast and dating from the Roman period, in collaboration with archeologists from the University of Buenos Aires and the Catalan Centre of Underwater Archaeology, in Gerona, Spain. Evaluating the lead isotopic composition of different archaeological lead objects and comparing this data with the isotopic composition of different ores can give information about the provenance of the mineral used for manufacturing those objects. Lead isotopes are 204Pb, 206Pb, 207Pb, 208Pb. These last three isotopes are radiogenic: they are produced by the natural decay chains of U and Th and therefore its abundance is not constant over time and is altered depending on the ore composition of U and Th. The concentration of 204Pb remains constant. Analyzing and plotting the lead isotopes abundance normalized to one of the isotopes (normally 204 or 206) can match a lead artifact between its possible source as a single ore deposit or a mixture of different ores. Two multi-collector mass spectrometers, the Finnigan MAT 262 and Triton Plus, were used for this analysis. Two Certified Reference Materials (CRM) were analyzed for Quality Control of the method (NIST-NBS SRM 982) and for bias correction due to mass fractionation (NIST-NBS SRM 981). An uncertainty of