Gebel Kamil: The iron meteorite that formed the Kamil crater (Egypt)
Gebel Kamil: The iron meteorite that formed the Kamil crater (Egypt)
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Gebel Kamil：形成卡米尔陨石坑的铁陨石（埃及）
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
C. Cordier
中科院分区：
文献类型：
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作者：
M. D’Orazio;L. Folco;A. Zeoli;C. Cordier
摘要-直径45 m的卡米尔陨石坑是5000年前在撒哈拉沙漠东部形成的，靠近现代埃及的南部边界。这个结构的原始特征，包括数千块陨石撞击器的碎片，保存得非常完好。除了一个83 公斤重的个体外，所有的格贝尔·卡米尔陨石(形成卡米尔陨石坑的铁陨石)都是爆炸碎片，重量从<；1 g到34 kg。Gebel Kamil是一个未分群的富镍(约20 wt%Ni)的斜方辉石，具有高的Ge和Ga含量(分别约为120 μg g−1和约50 μg g−1)和非常细粒的复相闪锌矿金属基质。Gebel Kamil中的副矿物相有施氏陨石、硫铁矿、闪锌矿和自然铜。陨石碎片被爆炸性的陆地撞击过程中形成的曲线剪切带横切。对陨石坑周围的系统搜索发现，陨石碎片具有高度的不对称分布，陨石碎片集中在东南区，最大集中在距离陨石坑边缘约200 m的12 5-16 0° N区。从本研究编制的密度图推算出弹片样品的总质量为3400 kg；10 g。野外资料表明，铁球从西北方向(305-340° N)接近地壳，沿一条中等倾斜的轨道行进。在超高速撞击时，弹丸被粉碎成数千块碎片。伴随着破碎的是抛射体和石英砂岩目标岩的一些熔融，它们也经历了冲击变质作用。
Abstract– The 45 m in diameter Kamil impact crater was formed <5000 yr ago in the eastern Sahara, close to the southern border of modern Egypt. The original features of this structure, including thousands of fragments of the meteorite impactor, are extremely well preserved. With the exception of a single 83 kg regmaglypted individual, all specimens of Gebel Kamil (the iron meteorite that formed the Kamil crater) are explosion fragments weighing from <1 g to 34 kg. Gebel Kamil is an ungrouped Ni‐rich (about 20 wt% Ni) ataxite characterized by high Ge and Ga contents (approximately 120 μg g−1 and approximately 50 μg g−1, respectively) and by a very fine‐grained duplex plessite metal matrix. Accessory mineral phases in Gebel Kamil are schreibersite, troilite, daubréelite, and native copper. Meteorite fragments are cross‐cut by curvilinear shear bands formed during the explosive terrestrial impact. A systematic search around the crater revealed that meteorite fragments have a highly asymmetric distribution, with greater concentrations in the southeast sector and a broad maximum in meteorite concentration in the 125–160° N sector at about 200 m from the crater rim. The total mass of shrapnel specimens >10 g, inferred from the density map compiled in this study is 3400 kg. Field data indicate that the iron bolide approached the Earth’s crust from the northwest (305–340° N), travelling along a moderately oblique trajectory. Upon hypervelocity impact, the projectile was disrupted into thousands of fragments. Shattering was accompanied by some melting of the projectile and of the quartz‐arenite target rocks, which also suffered shock metamorphism.