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Tellurium isotope compositions of calcium‐aluminum‐rich inclusions
Author(s) -
FEHR Manuela A.,
REHKÁMPER Mark,
HALLIDAY Alex N.,
HATTENDORF Bodo,
GÜNTHER Detlef
Publication year - 2009
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2009.tb00782.x
Subject(s) - allende meteorite , tellurium , analytical chemistry (journal) , chemistry , faraday cup , isotope , chondrite , radiochemistry , mineralogy , ion , meteorite , physics , nuclear physics , inorganic chemistry , organic chemistry , chromatography , astronomy , ion beam
— A method for the precise and accurate determination of the tellurium (Te) isotope compositions of calcium‐aluminum‐rich inclusions (CAIs) has been developed. The technique utilizes multiple‐collector inductively coupled plasma‐mass spectrometry (MC‐ICPMS) with either Faraday detectors or a dual ion‐counting system. The external reproducibility (2s̀) for 126 Te/ 125 Te was ?15% 0 and ?2% 0 when 3 pg and 65 pg of Te were analyzed with the electron multipliers. Measurements performed on 200 pg of Te using Faraday detectors and time‐resolved software displayed an external reproducibility of ?8% 0 for 126 Te/ 124 Te, whereas 3 ng Te could be measured to a precision of about 0.6% 0 . Analyses of five CAIs from the Allende chondrite yielded Te concentrations that range from 12 to 537 ppb and the inclusions are therefore depleted in Te relative to bulk Allende by factors of about 2 to 86. The Sn/Te ratios of the CAIs are also fractionated compared to bulk Allende (which displays 124 Sn/ 128 Te ??0.1) with 124 Sn/ 128 Te ratios of about 0.1 to 2.5. The Te isotope measurements for these refractory inclusions yielded no 126 Te excesses from the decay of the short‐lived radionuclide 126 Sn (ɛ1/2 = 234,500 years) and the most precise analysis provided a ɛ 126 Te value of 1 ±?6 (ɛ 126 Te = 126 Te/ 124 Te normalized to 122 Te/ 124 Te = 0.53594 and reported relative to the JMC Te standard). Minor differences in the Te isotope composition of the CAIs relative to the terrestrial standard and bulk Allende hint at the presence of small deficits in r‐process Te isotopes or excess of s‐process Te, but these nucleosynthetic anomalies are barely resolvable given the analytical uncertainties. Hence, it is also conceivable that these effects reflect small unresolved analytical artifacts.