Volcanism on Mars controlled by early oxidation of the upper mantle
Volcanism on Mars controlled by early oxidation of the upper mantle
复制标题
火星上的火山活动受上地幔早期氧化的控制
DOI：
10.1038/nature12225
复制
发表时间：
2013
期刊：
影响因子：
64.8
通讯作者：
Bernard J. Wood
中科院分区：
文献类型：
--
作者：
J. Tuff;Jon Wade;Bernard J. Wood
有关火星化学成分和演化的详细信息主要来自 SNC（shergottite-nakhlite-chassignite）陨石，它们是与火星起源相关的火成岩。它们在化学和结构上与陆地玄武岩和堆积岩相似，只是它们具有较高浓度的铁和挥发性元素（例如磷和氯）以及较低浓度的镍和其他亲铜（喜硫）元素。大多数火星陨石的结晶年龄相对较年轻（14亿年至1.8亿年前），被认为源自年轻的、有轻微火山口的火山地区，例如塔尔西斯高原。精神号火星车分析的古谢夫陨石坑的表面岩石要古老得多（大约有 37 亿年的历史），并且与陨石表现出明显的成分差异。虽然成分也是玄武岩，但表面岩石的镍和硫含量更高，锰/铁比也比陨石低。这导致人们怀疑是否可以使用“SNC 模型”来充分描述火星。然而，我们在这里表明，陨石和表面岩石的成分之间的差异可以通过同一富含硫的地幔熔化过程中氧逸度的差异来解释。这通过最上层地幔的早期（> 37亿年前）氧化将火星陨石的来源与表面岩石的来源联系起来，这种氧化对较深层区域的影响较小，而较深层区域产生了较新的火山岩。
Detailed information about the chemical composition and evolution of Mars has been derived principally from the SNC (shergottite–nakhlite–chassignite) meteorites, which are genetically related igneous rocks of Martian origin. They are chemically and texturally similar to terrestrial basalts and cumulates, except that they have higher concentrations of iron and volatile elements such as phosphorus and chlorine and lower concentrations of nickel and other chalcophile (sulphur-loving) elements. Most Martian meteorites have relatively young crystallization ages (1.4 billion years to 180 million years ago) and are considered to be derived from young, lightly cratered volcanic regions, such as the Tharsis plateau. Surface rocks from the Gusev crater analysed by the Spirit rover are much older (about 3.7 billion years old) and exhibit marked compositional differences from the meteorites. Although also basaltic in composition, the surface rocks are richer in nickel and sulphur and have lower manganese/iron ratios than the meteorites. This has led to doubts that Mars can be described adequately using the ‘SNC model’. Here we show, however, that the differences between the compositions of meteorites and surface rocks can be explained by differences in the oxygen fugacity during melting of the same sulphur-rich mantle. This ties the sources of Martian meteorites to those of the surface rocks through an early (>3.7 billion years ago) oxidation of the uppermost mantle that had less influence on the deeper regions, which produce the more recent volcanic rocks.