Understanding the transformations of highly reduced enstatite chondrites (EC) in terrestrial environments, even on very short timescales, is important to make the best use of the cosmochemical and mineralogical information carried by these extraterrestrial rocks. Analogs of EC meteorites were synthesized at high pressure and high temperature. Then, their aqueous alterations, either abiotic or in the presence of the bacteria Acidithiobacillus ferrooxidans or Acidithiobacillus thiooxidans, were studied under air, at pH ~2, 20 °C, and atmospheric pressure. They stayed in shaken batch reactors for 15 days. Reference experiments were carried out separately by altering only one mineral phase among those composing the synthetic EC (i.e., sulfides: troilite or Mg‐Ca‐rich sulfides, enstatite, and Fe₇₀Si₃₀). Composition of the alteration aqueous media and microstructures of the weathered solids were monitored by inductively coupled plasma atomic emission spectroscopy and by scanning electron microscopy, respectively. Alteration sequence of the different mineral components of the synthetic EC was found to occur in the following order: magnesium‐calcium sulfides > troilite > iron‐silicon metallic phase > enstatite regardless of the presence or absence of the microorganisms. Such small biological effects might be due to the fact that the alteration conditions are far from biologically optimal, which is likely the case in most natural environments. The exposed surfaces of an EC meteorite falling on Earth in a wet and acidic environment could lose within a few hours their Ca‐ and Mg‐rich sulfides (oldhamite and niningerite). Then, in <1 week, troilite and kamacite could be altered. In a wet and acidic environment, only the enstatite would remain intact and would weather on a much slower geological timescale.

中文翻译：

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合成顽辉石球粒陨石的水蚀和生物蚀变

即使在很短的时间范围内，也要了解在陆地环境中高度还原的顽辉陨石球粒晶（EC）的转变，对于充分利用这些地外岩石携带的宇宙化学和矿物学信息至关重要。EC陨石的类似物是在高压和高温下合成的。然后，它们的水相变化，无论是非生物的还是在细菌酸性氧化铁硫杆菌或酸性氧化硫杆菌的存在下，在空气中，pH〜2、20°C和大气压下进行了研究。他们在摇动的间歇反应器中呆了15天。通过仅改变组成合成EC的矿物相中的一个矿物相（即，硫化物：三菱沸石或富含Mg-Ca的硫化物，顽辉石和Fe ₇₀ Si _30）分别进行参考实验。）。分别通过感应耦合等离子体原子发射光谱法和通过扫描电子显微镜监测改变的水介质的组成和风化固体的微观结构。发现合成EC的不同矿物质成分的变化顺序按以下顺序发生：镁-硫化钙>闪锌矿>铁-硅金属相>顽辉石，无论是否存在微生物。如此小的生物学效应可能是由于这样的事实，即改变条件远非生物学上最佳，这在大多数自然环境中都是可能的。在潮湿和酸性环境中落在地球上的EC陨石的裸露表面可能会在数小时内失去其富含Ca和Mg的硫化物（菱锰矿和镍矿）。然后，在<1周内，可能会改变三叶石和金刚石。在潮湿和酸性的环境中，只有顽辉石会保持原样，并且会在很慢的地质时间尺度上风化。