High Precision Magnesium Isotopic Measurement of Cai Minerals with Low Al/mg Ratio from Allende Utilizing a Nanosims 50l Ion Microprobe
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Rare Earth Element Measurements of Melilite and Fassaite in Allende Cai by Nanosims
Introduction: The rare earth elements (REEs) are concentrated in CAIs by ~20 times the chondritic average [e.g., 1]. The REEs in CAIs are important to understand processes of CAI formation including the role of volatilization, condensation, and fractional crystallization [1,2]. REE measurements are a well-established application of ion microprobes [e.g., 3]. However the spatial resolution of RE...
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An ion microprobe ha~ been. used to observe Mg/"Mg in excess of normal values in anorthite crystals from Allende refractory mclus10ns. In one crystal, Mg excesses up to 40% above normal, correlated with AI/Mg, were. obser_ved. These ~xc~sses are many times larger than those observed by other techniques. T_he _correla~10n with Al(Mg mdicated tha_t the excess '"Mg in the Allende anorthite is unif...
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