Abstract The diversity of lithologies is an important proxy of internal evolution in differentiated planets and asteroids. The major lithologies in Vesta, based on the howardite-eucrite-diogenite clan meteorites, include basalt, gabbro, noritic orthopyroxenite, orthopyroxenite, dunite, harzburgite, and dacite. No other lithology has been reported up to date. In this study, we report a new occurrence of corundum in eucrite meteorite Northwest Africa (NWA) 8647. Three-dimensional petrographic observations reveal that the corundum grain occurs as a mineral inclusion in a highly deformed pyroxene fragment. The texture indicates that the corundum is not a contaminant. The corundum-associated pyroxenes have Fe-Mn compositions consistent with typical pyroxenes from howardite-eucrite-diogenite meteorites. We suggest that the corundum grain could be a xenocryst incorporated during the ascent of a basaltic magma. The results might indicate the presence of an Al-rich, Si-poor region, probably lithology in the interior of Vesta, implying that the evolution and internal structure should be much more complex than previously thought.

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刚玉刚玉的新发现及其意义

摘要 岩性多样性是分化行星和小行星内部演化的重要代表。灶神星的主要岩性以霍华德-辉长石-双闪长岩族陨石为基础，包括玄武岩、辉长岩、蓝长石正辉石、正辉石、纯英岩、方辉石和英安岩。迄今为止，还没有其他岩性报道。在这项研究中，我们报告了西北非 (NWA) 8647 赤晶陨石中新发现的刚玉。三维岩相观察显示，刚玉颗粒作为高度变形辉石碎片中的矿物包裹体出现。纹理表明刚玉不是污染物。刚玉伴生辉石的 Fe-Mn 组成与典型辉石来自霍华德辉石-辉长石-双生辉石陨石一致。我们认为刚玉颗粒可能是玄武岩岩浆上升过程中掺入的异晶。结果可能表明存在富铝、贫硅区域，可能是灶神星内部的岩性，这意味着演化和内部结构应该比以前认为的要复杂得多。