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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Sulfur isotopic compositions of individual sulfides in Martian meteorites ALH84001 and Nakhla: implications for crust-regolith exchange on Mars
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Sulfur isotopic compositions of individual sulfides in Martian meteorites ALH84001 and Nakhla: implications for crust-regolith exchange on Mars

机译：火星陨石ALH84001和Nakhla中单个硫化物的硫同位素组成：对火星上地壳-变石交换的影响

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Atmospheric chemical reactions on Mars have been invoked to explain non-mass-dependent Δ~(33)S anomalies (Δ~(33)S = δ~(33)S - 0.516δ~(34)S) reported from bulk analyses of Martian meteorites. To explore this signature in detail, a new ion microprobe multi-collector technique was developed to obtain precise in situ ~(32)S, ~(33)S and ~(34)S measurements of individual sulfide grains from Martian meteorites ALH84001 (>4.0 Ga) and Nakhla (1.3 Ga). This technique permits high-precision simultaneous measurement of multiple isotopes to uniquely evaluate Δ~(33)S at the grain scale (<30 μm). Our data reveal resolvable non-mass-dependent Δ~(33)S anomalies in two separate ALH84001 pyrite grains (Δ~(33)S = -0.74 ± 0.39‰ and -0.51 ± 0.38‰, 2250L?; none were detectable in Nakhla pyrrhotite (total range in Δ~(33)S = -0.4 ± 0.5‰ to -0.07 ± 0.5‰, 2σ). Our results might reflect a difference in how these meteorites exchanged sulfur with the Martian regolith and/or differences in their sources (atmospheric versus meteoritic) of anomalous sulfur. Nebular heterogeneities in sulfur isotope composition are indicated by Δ~(33)S anomalies preserved in, for example, the ureilites. The Δ~(33)S anomalies in ALH84001 pyrite could suggest that early (pre-4 Ga) additions of a meteoritic component carried isotopically anomalous sulfur to the Martian regolith, and was stored there as seen in the detection of Δ~(33)S anomalies from bulk measurements of Nakhla. Therefore, meteoritic contributions should also be considered in addition to atmospheric effects when explaining the large non-mass-dependent anomalies seen in Martian meteorites. These studies provide insight into how hydrothermal systems have facilitated exchange between volatile reservoirs on Mars, a planet that lacks efficient crustal recycling mechanisms and preserves ancient (and anomalous) Δ~(33)S signatures.
机译：火星上的大气化学反应被用来解释非质量相关的Δ〜（33）S异常（Δ〜（33）S =δ〜（33）S-0.516δ〜（34）S）火星陨石。为了详细探索该特征，开发了一种新的离子微探针多收集器技术，以从火星陨石ALH84001中获得单个硫化物晶粒的精确〜（32）S，〜（33）S和〜（34）S精确测量值（> 4.0 Ga）和Nakhla（1.3 Ga）。该技术允许高精度同时测量多个同位素，从而在晶粒度（<30μm）处唯一地评估Δ〜（33）S。我们的数据揭示了两个单独的ALH84001黄铁矿晶粒中的可分辨的非质量相关的Δ〜（33）S异常（Δ〜（33）S = -0.74±0.39‰和-0.51±0.38‰，2250L?;没有检测到在纳赫拉（Nakhla）黄铁矿中（Δ〜（33）S的总范围= -0.4±0.5‰至-0.07±0.5‰，2σ）。我们的结果可能反映了这些陨石与火星重辉石交换硫的方式的不同和/或硫同位素组成中的星状异质性由保留在例如尿素岩中的Δ〜（33）S异常指示，ALH84001黄铁矿的Δ〜（33）S异常可能表明早期（Ga 4之前）添加的陨石成分将同位素异常硫带到火星的长石，并从那赫拉的大量测量中检测到Δ〜（33）S异常时被存储在那里，因此，陨石的贡献也应在解释较大的非质量依赖项时，除考虑大气效应外，还应考虑火星陨石中发现的nt异常。这些研究提供了关于热液系统如何促进火星上的挥发性储层之间交换的见解，该行星缺乏有效的地壳再循环机制，并保留了古老的（和异常的）Δ〜（33）S特征。

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