Mg isotope heterogeneity in the Allende meteorite measured by UV laser ablation-MC-ICPMS and comparisons with O isotopes
Mg isotope heterogeneity in the Allende meteorite measured by UV laser ablation-MC-ICPMS and comparisons with O isotopes
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DOI：
10.1016/s0016-7037(01)00796-7
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发表时间：
2002-02
影响因子：
5
通讯作者：
E. Young;R. Ash;A. Galy;N. Belshaw
中科院分区：
文献类型：
--
作者：
E. Young;R. Ash;A. Galy;N. Belshaw
首次用一种新的紫外激光消融MC-ICPMS方法对陨石中的镁同位素进行了原位测量，结果表明，阿伦德陨石球粒中δ25 mg和δ26 mg随质量的变化高达1.5amu/amu和0.3amu/amu。在这两种情况下，与质量有关的分馏都与蚀变有关。与激光烧蚀氧同位素数据的对比表明，具有不同镁和氧同位素组成的先前存在的镁橄榄岩颗粒的并入和建造后的蚀变都有助于球粒陨石中镁同位素比值的变化，从而导致高δ25 mg和低Δ17O之间的相关性。激光烧蚀分析表明，δ25 mg和δ26 mg的高精度测定可用于区分26Al-26 mg同位素体系中与年代学有关的特征和元素活动性的特征。
First results from a new UV laser ablation MC-ICPMS method for measuring Mg isotope ratios in situ in meteoritical materials show that there are mass-dependent variations in δ25Mg and δ26Mg up to 1.5 ‰ per amu in chondrules and 0.3‰ per amu in a CAI from the Allende meteorite. In both cases the mass-dependent fractionation is associated with alteration. Comparisons with laser ablation O isotope data indicate that incorporation of pre-existing grains of forsterite with distinct Mg and O isotopic compositions and post-formation alteration both contributed to the variability in Mg isotope ratios in the chondrules, resulting in a correlation between high δ25Mg and low Δ17O. The laser ablation analyses of the CAI show that high-precision determinations of both δ25Mg and δ26Mg can be used to discriminate features of the26Al-26Mg isotope system that are relevant to chronology from those that result from element mobility.