ABSTRACT

The Os isotopic composition and abundances of highly siderophile elements (HSE; Re, Os, Ir, Ru, Pt, Rh, Pd, and Au) and volatile chalcophile elements (VCE; S, Ge, As, Se, Sn, Sb, and Te) in chondrites show considerable variabilities across different chondrite groups, which provide essential insights into understanding the elemental fractionation during the formation of chondrite parent bodies and their precursor materials. Here, we have developed a method using a sealed glass tube digestion to simultaneously measure the ¹⁸⁷Os/¹⁸⁸Os ratios and the abundances of HSEs, VCEs, and other elements including Mg, Al, Ca, and Mo in chondrites. This study evaluated the potential blank increase from the quartz tube digestion and subsequent chemical process and the loss of other elements from the Os extraction processes. The new method was validated by the repeated measurements of the Allende meteorite reference sample provided by the Smithsonian Institution (Smithsonian Allende). The elemental abundances were determined by the isotope dilution (ID) coupled with ICP-MS/MS, excluding those of Mg, Al, Ca, As, Mo, Rh, and Au that were determined by a combination of ID and internal standardization (IS). The reproducibility of ten replicate analyses generally yielded less than 10%, except for Sn, Sb, and Mo, which is consistent with existing literature data. The analysis of the Re-Os systematics of minute sample powders revealed insights into their chemical heterogeneity. In particular, this study gives compelling evidence that the chemical heterogeneity observed in the Smithsonian Allende is closely related to sample size.