Quantification of oxygen isotope SIMS matrix effects in olivine samples: Correlation with sputter rate

Abstract

A B S T R A C TWe investigated the magnitude and reproducibility of instrumental mass-dependent fractionation of oxygen isotopes in secondary ion mass spectrometry (SIMS) analyses of olivine crystals of different major element chemistry (from Mg-rich to Fe-rich) in order to improve the accuracy of in-situ O-isotope measurements in geochemical/cosmochemical olivine samples. We found that oxygen isotope SIMS matrix effects are reproducible, and developed a model curve that can be used for correcting instrumental mass fractionation of olivine samples of intermediate chemical composition. The changes in instrumental mass fractionations were likely caused by differing Cs concentrations in the near surface regions of the samples due to different sample sputtering rates.

SIMS Bias on Isotope Ratios in Ca‐Mg‐Fe Carbonates (Part III): δ18O and δ13C Matrix Effects Along the Magnesite–Siderite Solid‐Solution Series

“…, Isa et al . ), this could significantly improve our understanding of what drives the first‐order differences of ~ 10–20‰ in bias magnitude between the end‐members of the dolomite–ankerite and magnesite–siderite solid‐solution series.…”

“…, Isa et al . ). Nonetheless, what is apparent from the data at hand is that above a certain threshold Fe mass fraction, carbonate δ 18 O bias calibration curve shapes are strongly influenced by session‐specific differences in instrument tuning (reflected by the resulting pit morphologies/geometries).…”

High‐precision in situ silicon isotopic analyses by multi‐collector secondary ion mass spectrometry in olivine and low‐calcium pyroxene

“…In contrast, it may be preferable to analyze high‐FeO olivines with the RF source, although the Si ion yield is lower. In any case, as with Mg and O isotopic measurements in olivine, a comprehensive set of standards is needed to avoid artificial isotopic fractionations and to ensure high‐precision IMF corrections for Si isotopes.…”

“…For instance, it has been shown that (i) IMF varies linearly with the mass‐to‐charge ratio of octahedral cations (e.g. Mn, Mg, Fe, Ti) as they impact the strength of the OH and OB bond for analyses of 2 H/ 1 H in micas and amphiboles and 11 B/ 10 B in tourmaline, (ii) IMF during 18 O/ 16 O analyses in silicates depends on the SiO 2 and FeO contents, (iii) IMF during 18 O/ 16 O analyses in carbonates depends on Fe, Mg, and Mn contents, and (iv) IMF during 30 Si/ 28 Si and 44 Ca/ 40 Ca analyses in CaO–MgO–Al 2 O 3 –SiO 2 (CMAS) glasses varies linearly with optical basicity . Thus, for a given isotopic system, it is often possible to build an empirical calibration from measurements of a limited number of well‐chosen standards, and interpolate IMF values for different (but related) compositions.…”

In Situ Oxygen Isotope Determination in Serpentine Minerals by Ion Microprobe: Reference Materials and Applications to Ultrahigh‐Pressure Serpentinites

“…(, ), and Isa et al . (), in order to evaluate instrumental reproducibility as well as the behaviour of serpentine (a phyllosilicate) under the Cs + primary ion beam relative to other minerals commonly analysed by ion microprobes (nesosilicates). Olivine was chosen as a reference material because it has a chemical composition relatively similar to that of serpentine.…”