SIMS Bias on Isotope Ratios in Ca-Mg-Fe Carbonates (Part III): δ 18 O and δ 13 C Matrix Effects Along the Magnesite-Siderite Solid-Solution Series
SIMS Bias on Isotope Ratios in Ca-Mg-Fe Carbonates (Part III): δ 18 O and δ 13 C Matrix Effects Along the Magnesite-Siderite Solid-Solution Series
复制标题
Ca-Mg-Fe 碳酸盐中同位素比的 SIMS 偏差（第三部分）：沿菱镁矿-菱铁矿固溶体系列的 δ 18 O 和 δ 13 C 基体效应
DOI：
10.1111/ggr.12194
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发表时间：
2018
影响因子：
3.8
通讯作者：
Valley, John W.
中科院分区：
文献类型：
--
作者：
Śliwiński, Maciej G.;Kitajima, Kouki;Spicuzza, Michael J.;Orland, Ian J.;Ishida, Akizumi;Fournelle, John H.;Valley, John W.
本研究探讨了阳离子组成对质量偏差的影响（即，基质效应），这是通过西姆斯对菱镁矿-菱铁矿固溶体系列（MgCO 3-FeCO 3）碳酸盐中δ 13 C和δ 18 O进行微量分析时仪器质量分馏（IMF）的主要组成部分。开发并记录了一套12种校准参比物质（RM）（校准范围：Fe# = 0.002-0.997，其中Fe# =摩尔Fe/[Mg + Fe]），沿着用于回归校准数据的经验表达式（相对于经认证的参比物质NIST-19，残差< 0.5‰）。两种同位素系统的校准曲线都是非线性的，在2年的时间里，它们属于两种不同但基本上自洽的形状类别之一（来自10次测量的数据），尽管在WiscSIMS（CAMECA IMS 1280）中遵守了碳酸盐δ 13 C和δ 18 O分析的成熟分析方案。质量偏差始终对菱镁矿端元（Fe# 0-0.2）附近的成分变化最敏感，随着Fe含量的增加，偏差高达4.5‰（δ 13 C）和14‰（δ 18 O）。目前尚未充分了解校准曲线形状变异性的原因，这证明了拥有足够数量的充分表征的RM的重要性，以便可以在逐个会话的基础上充分描述和解释曲率的潜在复杂性。
This study explores the effects of cation composition on mass bias (i.e., the matrix effect), which is a major component of instrumental mass fractionation (IMF) in the microanalyses of δ13C and δ18O by SIMS in carbonates of the magnesite–siderite solid‐solution series (MgCO3–FeCO3). A suite of twelve calibration reference materials (RMs) was developed and documented (calibrated range: Fe# = 0.002–0.997, where Fe# = molar Fe/[Mg + Fe]), along with empirical expressions for regressing calibration data (affording residuals < 0.5‰ relative to certified reference material NIST‐19). The calibration curves of both isotope systems are non‐linear and have, over a 2‐year period, fallen into one of two distinct but largely self‐consistent shape categories (data from ten measurement sessions), despite adherence to well‐established analytical protocols for carbonate δ13C and δ18O analyses at WiscSIMS (CAMECA IMS 1280). Mass bias was consistently most sensitive to changes in composition near the magnesite end‐member (Fe# 0–0.2), deviating by up to 4.5‰ (δ13C) and 14‰ (δ18O) with increasing Fe content. The cause of variability in calibration curve shapes is not well understood at present and demonstrates the importance of having available a sufficient number of well‐characterised RMs so that potential complexities of curvature can be adequately delineated and accounted for on a session‐by‐session basis.