Recognizing mercurian meteorites
Recognizing mercurian meteorites
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识别水星陨石
DOI：
10.1111/j.1945-5100.1995.tb01125.x
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
K. Keil
中科院分区：
文献类型：
--
作者：
S. Love;K. Keil
- 随着最近意识到一些陨石可能来自火星和月球，值得考虑的是，来自水星的陨石是否可能存在于我们的收藏中，如果是这样，它们是否可以被识别。目前对水星的无知既增加了水星陨石的潜在科学价值，也增加了识别它们的问题。在这里，我们回顾证据支持的影响发射和随后的轨道演变，可以提供岩石从水星到地球的可能性，并提出标准，可以帮助确定水星陨石。汞岩可能是由其衍生的分异火成岩或角砾岩或熔融岩。太阳星云模型表明，它们可能是低挥发性和适度丰富的铝，钛和钙的氧化物。水星表面岩石含有不超过5%的FeO，可能含有斜长石。很大一部分可能是火山岩。它们可能具有不寻常的同位素组成。大多数原始汞质岩石的凝固年龄应该在3.7 ~ 4.4 Ga之间，但可能存在更年轻的撞击重熔物质。因为我们对水星的太空环境比对水星本身的了解更多，所以表面暴露的岩石最容易被识别为水星。在太阳附近暴露的材料中，独特的太阳-银河宇宙射线损伤轨迹比可能有助于识别水星的岩石。水星的磁场远离太阳风，因此水星风化角砾岩中的太阳风植入物与月球的相比可能是稀少或分散的。水星风化角砾岩应包含更多的凝集物（或其重结晶衍生物）和冲击蒸气沉积物比任何其他，并应显示出比类似的月球角砾岩更高的外生碎屑物质的分数。没有已知的陨石群符合这些标准。一个错误分类的水星陨石很可能是在Aubrites或斜长岩月球陨石中发现的。
— With the recent realization that some meteorites may come from Mars and the Moon, it is worthwhile to consider whether meteorites from Mercury could exist in our collections and, if so, whether they could be recognized. The current state of ignorance about Mercury both increases the potential scientific value of mercurian meteorites and aggravates the problem of identifying them. Here, we review evidence supporting the possibility of impact launch and subsequent orbital evolution that could deliver rocks from Mercury to Earth and suggest criteria that could help identify a mercurian meteorite. Mercurian rocks are probably differentiated igneous rocks or breccias or melt rocks derived therefrom. Solar nebula models suggest that they are probably low in volatiles and moderately enriched in Al, Ti, and Ca oxides. Mercurian surface rocks contain no more than 5% FeO and may contain plagioclase. A significant fraction may be volcanic. They may possess an unusual isotopic composition. Most pristine mercurian rocks should have solidification ages of ∼3.7 to ∼4.4 Ga, but younger impact-remelted materials are possible. Because we know more about the space environment of Mercury than we do about the planet itself, surface-exposed rocks would be easiest to identify as mercurian. The unique solar-to-galactic cosmic-ray damage track ratio expected in materials exposed near the Sun may be useful in identifying a rock from Mercury. Mercury's magnetic field stands off the solar wind, so that solar-wind implants in mercurian regolith breccias may be scarce or fractionated compared to lunar ones. Mercurian regolith breccias should contain more agglutinates (or their recrystallized derivatives) and impact vapor deposits than any other and should show a higher fraction of exogenic chondritic materials than analogous lunar breccias. No known meteorite group matches these criteria. A misclassified mercurian meteorite would most likely be found among the aubrites or the anorthositic lunar meteorites.