Particle ejection and redeposition events on the surface of asteroid 101955 Bennu, which led to transport, mixing and loss of material, have been observed frequently by NASA’s OSIRIS-REx mission. Besides large-scale impacts, this may be one of the most important post-accretional processes on small carbonaceous asteroids. Here we looked for relics of such activity in a Bennu analogue, the carbonaceous chondrite Aguas Zarcas. We discovered compact fragments that were strongly shocked, redistributed and deposited onto an unshocked lithology, consistent with surficial re-accretion on Aguas Zarcas’s parent body. Such re-accretion could be driven by large-scale impacts or by frequent pebble transport from endogenous asteroidal activity such as observed at Bennu. The latter hypothesis is supported by the matching size distribution of the Aguas Zarcas compact fragments with that of the Bennu ejecta. Such mixing has hitherto been unexplored in other regolith breccias, and further analysis will determine how common such processes are.

NASA 的 OSIRIS-REx 任务经常观察到小行星 101955 Bennu 表面的粒子喷射和再沉积事件，这些事件导致了物质的运输、混合和损失。除了大规模撞击外，这可能是小型碳质小行星最重要的后吸积过程之一。在这里，我们在 Bennu 类似物碳质球粒陨石 Aguas Zarcas 中寻找这种活动的遗迹。我们发现致密碎片受到强烈冲击、重新分布并沉积在未冲击的岩性上，这与 Aguas Zarcas 母体上的地表重新吸积一致。这种重新吸积可能是由大规模撞击或内源性小行星活动频繁的卵石运输驱动的，例如在本努观察到的。后一种假设得到了 Aguas Zarcas 致密碎片与 Bennu 喷射物的匹配尺寸分布的支持。迄今为止，这种混合在其他风化角砾岩中还没有被探索过，进一步的分析将确定这种过程的普遍程度。