Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, UMR 7358, 54501 Vandoeuvre-lès-Nancy, France.
Institut de Physique du Globe de Paris, Université Sorbonne Paris Cité, 75238 Paris, France.
Sci Adv. 2016 Jul 1;2(7):e1601001. doi: 10.1126/sciadv.1601001. eCollection 2016 Jul.
Meteoritic chondrules are submillimeter spherules representing the major constituent of nondifferentiated planetesimals formed in the solar protoplanetary disk. The link between the dynamics of the disk and the origin of chondrules remains enigmatic. Collisions between planetesimals formed at different heliocentric distances were frequent early in the evolution of the disk. We show that the presence, in some chondrules, of previously unrecognized magnetites of magmatic origin implies the formation of these chondrules under impact-generated oxidizing conditions. The three oxygen isotopes systematic of magmatic magnetites and silicates can only be explained by invoking an impact between silicate-rich and ice-rich planetesimals. This suggests that these peculiar chondrules are by-products of the early mixing in the disk of populations of planetesimals from the inner and outer solar system.
陨石球粒是亚毫米级的球体，代表了在太阳原行星盘中形成的未分化的星子的主要成分。盘的动力学与球粒的起源之间的联系仍然是个谜。在盘的演化早期，形成于不同日心距离的星子之间的碰撞是频繁的。我们表明，在一些球粒中存在以前未被识别的岩浆磁铁矿，这意味着这些球粒是在冲击产生的氧化条件下形成的。岩浆磁铁矿和硅酸盐的三个氧同位素系统只能通过富含硅酸盐和富含冰的星子之间的撞击来解释。这表明这些特殊的球粒是太阳系内外行星子群在盘中早期混合的副产物。
