title: High-precision measurement of (186)Os/(188)Os and (187)Os/(188)Os: isobaric oxide corrections with in-run measured oxygen isotope ratios.
abstract: We present a novel method for high precision measurement of (186)Os/(188)Os and (187)Os/(188)Os ratios, applying isobaric oxide interference correction based on in-run measurements of oxygen isotopic ratios. For this purpose, we set up a static data collection routine to measure the main Os(16)O3(-) ion beams with Faraday cups connected to conventional 10(11) amplifiers, and (192)Os(16)O2(17)O(-) and (192)Os(16)O2(18)O(-) ion beams with Faraday cups connected to 10(12) amplifiers. Because of the limited number of Faraday cups, we did not measure (184)Os(16)O3(-) and (189)Os(16)O3(-) simultaneously in-run, but the analytical setup had no significant influence on final (186)Os/(188)Os and (187)Os/(188)Os data. By analyzing UMd, DROsS, an in-house Os solution standard, and several rock reference materials, including WPR-1, WMS-1a, and Gpt-5, the in-run measured oxygen isotopic ratios were proven to present accurate Os isotopic data. However, (186)Os/(188)Os and (187)Os/(188)Os data obtained with in-run O isotopic compositions for the solution standards and rock reference materials show minimal improvement in internal and external precision, compared to the conventional oxygen correction method. We concluded that, the small variations of oxygen isotopes during OsO3(-) analytical sessions are probably not the main source of error for high precision Os isotopic analysis. Nevertheless, use of run-specific O isotopic compositions is still a better choice for Os isotopic data reduction and eliminates the requirement of extra measurements of the oxygen isotopic ratios.
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Zhu-Yin
authors.initials: ZY
authors.lastname: Chu
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Chao-Feng
authors.initials: CF
authors.lastname: Li
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences , Beijing 100029, China.|College of Earth Sciences, University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.affiliation: School of Ocean Sciences, China University of Geosciences , Beijing 100083, China.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Xu
authors.affiliation: Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University , Beijing 100871, China.
authors.forename: Yan-Kun
authors.initials: YK
authors.lastname: Di
authors.affiliation: State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences , Beijing 100029, China.
authors.forename: Jing-Hui
authors.initials: JH
authors.lastname: Guo