Pristine extraterrestrial material with unprecedented nitrogen isotopic variation
Pristine extraterrestrial material with unprecedented nitrogen isotopic variation
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DOI：
10.1073/pnas.0901546106
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发表时间：
2009-06-30
影响因子：
11.1
通讯作者：
Meibom, Anders
中科院分区：
文献类型：
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作者：
Briani, Giacomo;Gounelle, Matthieu;Meibom, Anders
原始陨石物质携带轻元素同位素分馏，限制了太阳系形成过程中的物理化学条件。在这里，我们报告发现了一个独特的捕虏体中的金属丰富的球粒陨石Isheyevo。其细粒、高度原始的矿物学与行星际尘埃颗粒（IDP）相似，但捕虏体的体积是典型IDP的30，000倍以上。此外，捕虏体中的N同位素变化极端连续：从非常轻的N同位素组成（Δ N-15（AIR）= -310 +/- 20%），类似于太阳星云的推断，到在任何太阳系物质中测量到的最重的比率（Δ N-15（AIR）= 4，900 +/- 300%）。同时，其氢和碳同位素组成变化很小。这一目标对轻元素同位素异常起源的现有模型提出了严峻的挑战。
Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (delta N-15(AIR) = -310 +/- 20%), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (delta N-15(AIR) = 4,900 +/- 300%). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies.