Optimizing Analysis And Application Of Re-Os And Mo Isotope With PGE And S

The unique geochemical characteristics of Re-Os system make it become an irreplaceable tool in earth science research. It displays distinct advantages in isotopic geochemical tracing and dating. But because of the extremely low Re-Os content in geological samples, development of Re-Os chemical separation and instrument analysis technique is one of the directions of geochemists are studying. The use of HF in Re-Os digeation of geological samples remains controversial. So research on the influence of HF desilicification is one of the hot topics in the study of Re-Os analysis technology optimization. In this study, Re and Os isotopes were systematically determined in six geological reference materials(RMs, covering a wide range of lithologies) using the Carius tube(CT) digestion technique with and without hydrofluoric acid desilicification. For desilicification analysis, HF+HCl digestion is compared with HF+HBr digestion. It is better to add spike with sample in Carius tube after HF+HCl or HF+HBr digestion. With desilicification or not, Re concentrations of the six RMs are in good repeatability, and Os concentrations of one sample span a wide range. Such features impliy that Re and Os are not controlled by the same phases. With desilicification in Carius tube digeation, Re and Os concentration elevated, and 187Os/188 Os ratio changed, particularly for basaltic and andesitic rocks.In this paper, beneficial exploration in analysis of platinum group elements(PGE) and S which closely related to Re-Os isotope system was made.We present an improved procedure for determination of PGE-Re concentrations and 187Os/188 Os ratios of the environmental reference material BCR-723. These are the ?rst comprehensive PGE and Re concentrations and Os isotopic compositions reported for BCR-723 and provide a well-characterized standard for assessing the data quality of autocatalyst PGE measurements and related research on environmental materials. The method was successfully employed in the determination of PGE-Re concentrations and Os isotopic compositions in urban road dust samples from Guangzhou. All samples show not only a Pt and Pd significantly beyond the natural background value, Os, Ru, Ir and Re also the same. Samples of Pd, Ru, Ir and correlation between Pt and other Chinese cities road dust sample data indicate the sources of these elements related to human activities. Automotive catalysts are the only known source of road dust PGE in Guangzhou region.Simultaneous determination of sulfur content and Re-Os isotope was established. Measurements of the IAEA-S-2, IAEA-S-3 and IAPSO(seawater) are consistent with the literature values. It illustrates the established MC-ICP-MS determination method can accurately measure sulfur isotopic composition of solution sample. Cation resin adsorp the matrix elements in rock samples closely during the process of separation. Sulfur is separated with the matrix elements ideally. Rock reference material BHVO-2 are analyzed, and the content of S is in no obvious correlation with Re and Os. That means BHVO-2 is not directly related with the amount of S dissolved. In this paper, the changes of sulfur content in the range is very large, it could have been obscures the relevance of sulfur content with Re and Os. To verify the accuracy of the established method, eliminate the experimental process explain the influence of the result of the sulfur content.Molybdenum(Mo) isotope geochemistry has developed rapidly in recent years.We used the double-spike method with multi-collector–inductively coupled plasma–mass spectrometry to measure the Mo mass fractions and isotopic composition of a set of geological reference materials including the mineral molybdenite, seawater, coral, as well as igneous and sedimentary rocks. The comprehensive dataset presented in this study serves as a reference for quality assurance and inter-laboratory comparison of high-precision Mo mass fractions and isotopic compositions.Our researches unravel that the pyroxenite indeed may be the reservoir of radioactive 187Os/188 Os in the marble-cake mantle, but their Re-Os isotopic compositions are much more heterogenous than previously thought. Therefore, prior to discriminating whether the pyroxenite is involved in magma generation, the formation and geodynamic background of pyroxenite must be articulated primarily.