Open AccessIon microprobe evidence for the presence of excess 26 Mg in an Allende anorthite crystal
Author(s) -
Bradley J. G.,
Huneke J. C.,
Wasserburg G. J.
Publication year - 1978
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/jb083ib01p00244
Subject(s) - anorthite , allende meteorite , electron microprobe , ion , crystal (programming language) , analytical chemistry (journal) , melilite , mineralogy , microprobe , materials science , chemistry , meteorite , chondrite , physics , metallurgy , astrobiology , chromatography , programming language , spinel , computer science , organic chemistry
An ion microprobe has been used to observe 26 Mg/ 24 Mg in excess of normal values in anorthite crystals from Allende refractory inclusions. In one crystal, 26 Mg excesses up to 40% above normal, correlated with Al/Mg, were observed, These excesses are many times larger than those observed by other techniques. The correlation with Al/Mg indicated that the excess 26 Mg in the Allende anorthite is uniformly distributed in the anorthite crystal. Analytical procedures and conditions were carefully controlled. Nevertheless, small but significant apparent 26 Mg/ 24 Mg anomalies in isotopically normal samples were observed in analyses by one ion microprobe. A repetition of the isotopic analyses using another ion probe produced normal ratios in the normal samples and confirmed large 26 Mg excesses in the Allende anorthite.
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