New constraints on ages of glasses proposed as reference materials for fission-track dating
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Data
2007-06-01
Autores
Laurenzi, Marinella A.
Balestrieri, Maria Laura
Bigazzi, Giulio
Neto, Julio C. Hadler
Iunes, Pedro J.
Norelli, Pio
Oddone, Massimo
Osorio Araya, Ana Maria
Viramonte, Jose G.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Wiley-Blackwell
Resumo
New analyses have been performed in order to enhance the data-set on the independent ages of four glasses that have been proposed as reference materials for fission-track dating. The results are as follows. Moldavite - repeated (40)Ar/(39)Ar age determinations on samples from deposits from Bohemia and Moravia yielded an average of 14.34 +/- 0.08 Ma. This datum agrees with other recent determinations and is significantly younger than the (40)Ar/(39)Ar age of 15.21 +/- 0.15 Ma determined in the early 1980s. Macusanite (Peru) -four K-Ar ages ranging from 5.44 +/- 0.06 to 5.72 +/- 0.12 Ma have been published previously. New (40)Ar/(39)Ar ages gave an average of 5.12 +/- 0.04 Ma. Plateau fission-track ages determined using the IRMM-540 certified glass and U and Th thin films for neutron fluence measurements agree better with these new (40)Ar/(39)Ar ages than the previously published ages. Roccastrada glass (Italy) - a new (40)Ar/(39)Ar age, 2.45 +/- 0.04 Ma, is consistent with previous determinations. The Quiron obsidian (Argentina) is a recently discovered glass that has been proposed as an additional reference material for its high spontaneous track density (around 100 000 cm(-2)). Defects that might produce spurious tracks are virtually absent. An independent (40)Ar/(39)Ar age of 8.77 +/- 0.09 Ma was determined and is recommended for this glass. We believe that these materials, which will be distributed upon request to fission-track groups, will be very useful for testing system calibrations and experimental procedures.
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Palavras-chave
fission-track dating, (40)Ar/(39)Ar dating, natural glasses, age standards
Como citar
Geostandards and Geoanalytical Research. Malden: Wiley-blackwell, v. 31, n. 2, p. 105-124, 2007.