Southward impact excavated magma ocean at the lunar South Pole-Aitken basin

• 成果类型: Article
• 署名作者: Andrews-Hanna, Jeffrey C.; Bottke, William F.; Broquet, Adrien; Evans, Alexander J.; Gowman, Gabriel; Johnson, Brandon C.; Keane, James T.; Levin, Janette N.; Mallik, Ananya; Marchi, Simone; Moruzzi, Samantha A.; Roy, Arkadeep; Wakita, Shigeru
• 署名单位: University of Arizona; National Aeronautics & Space Administration (NASA); Southwest Research Institute; Helmholtz Association; German Aerospace Centre (DLR); Brown University; Purdue University System; Purdue University; Purdue University System; Purdue University; California Institute of Technology; National Aeronautics & Space Administration (NASA); NASA Jet Propulsion Laboratory (JPL); University of Arizona
• 刊物名称: NATURE
• ISSN/ISSBN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-025-09582-y
• 发表日期: 2025-10-09
• 关键词: MOON; origin; differentiation; bombardment; crystallization; EVOLUTION; volcanism; TIMELINE; FARSIDE; crust

摘要

The ancient South Pole-Aitken impact basin provides a key data point for our understanding of the evolution of the Moon, as it formed during the earliest pre-Nectarian epoch of lunar history1, excavated more deeply than any other known impact basin2,3 and is found on the lunar far side, about which less is known than the well-explored near side. Here we show that the tapering of the basin outline and the more gradual topographic and crustal thickness transition towards the south support a southward impact trajectory, opposite of that commonly assumed. A broad thorium-rich and iron-rich ejecta deposit southwest of the basin is consistent with partial excavation of late-stage magma ocean liquids. These observations indicate that thorium-rich magma ocean liquids persisted only beneath the southwestern half of the basin at the time of impact, matching predictions for the transition from a global magma ocean to a local enrichment of potassium, rare-earth elements and phosphorus (KREEP) in the near-side Procellarum KREEP Terrane. These results have important implications for the upcoming human exploration of the lunar south pole by Artemis, as proposed landing sites are now recognized to sit on the downrange rim and thorium-rich impact ejecta of the basin.