A unique CO-like micrometeorite hosting an exotic Al-Cu-Fe-bearing assemblage – close affinities with the Khatyrka meteorite
A unique CO-like micrometeorite hosting an exotic Al-Cu-Fe-bearing assemblage – close affinities with the Khatyrka meteorite
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一种独特的类二氧化碳微陨石，含有奇异的含铝-铜-铁组合——与哈蒂尔卡陨石密切相关
DOI：
10.1038/s41598-019-48937-0
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发表时间：
2019
影响因子：
4.6
通讯作者：
L. Folco
中科院分区：
文献类型：
--
作者：
M. Suttle;K. Twegar;J. Nava;R. Spiess;J. Spratt;F. Campanale;F. Campanale;L. Folco
我们报告了一个独特的微陨石的发现，包含一个外来的Al-Cu-Fe合金组成的两个混合相：卡特尔石（CuAl 2）和stolperite（CuAl），都含有微量的铁（<1.4重量%）。这些相是树枝状的，并且在二元系统的临界温度（~550 °C）下快速共结晶。寄主微陨石为典型的S型微斑状宇宙球粒，含残余橄榄石（Fo 76 -90，Cr 2 O 3：0.01- 0.56wt%，MnO：0.03- 0.32wt%，CaO：0.09- 0.22wt%）和堆积层状结构。这些性质表明，微陨石是由碳质球粒陨石（最佳匹配CO球粒陨石），并进入大气层的高速（~16 kms−1），意味着起源于一个高度偏心的轨道。该颗粒代表了第二次独立发现的天然金属间Al-Cu-Fe合金，因此类似于先前报道的Khatyrka陨石-一种CV球粒陨石，含有几乎相同的合金和唯一已知的天然准晶体。我们没有观察到准晶相在这个微陨石，可能是由于低量的铁合金，不足以稳定准晶。我们的发现证实了Al-Cu-Fe金属间化合物合金在奥氏体基体上的存在。这些不寻常的阶段需要一个目前无法解释的形成过程，我们初步认为这可能代表了外来星际物质通过撞击传递到太阳系内部。
We report the discovery of a unique micrometeorite, containing an exotic Al-Cu-Fe alloy composed of two intermixed phases: khatyrkite (CuAl2) and stolperite (CuAl) and both containing minor Fe (<1.4 wt%). These phases are dendritic and rapidly co-crystallized at the binary system’s peritectic (~550 °C). The host micrometeorite is an otherwise typical S-type micro-porphyritic cosmic spherule containing relict olivine (Fo76–90, Cr2O3: 0.01–0.56 wt%, MnO: 0.03–0.32 wt% and CaO: 0.09–0.22 wt%) and a cumulate layered texture. These properties suggest the micrometeorite is derived from a carbonaceous chondrite (best matched to a CO chondrite) and entered the atmosphere a high speed (~16 kms−1), implying an origin from a highly eccentric orbit. This particle represents the second independent discovery of naturally occurring intermetallic Al-Cu-Fe alloys and is thus similar to the previously reported Khatyrka meteorite - a CV chondrite containing near-identical alloys and the only known natural quasicrystals. We did not observe quasicrystalline phases in this micrometeorite, likely due to the low amounts of Fe in the alloy, insufficient to stabilize quasicrystals. Our discovery confirms the existence of Al-Cu-Fe intermetallic alloys on chondritic parent bodies. These unusual phases require a currently unexplained formation process, we tentatively suggest this could represent the delivery of exotic interstellar material to the inner solar system via impact.
大气减速期间橄榄石沉降在宇宙球粒中：行星际尘埃轨道偏心率的指标
影响因子：
5.2
作者：
Genge M
通讯作者：
Genge M