期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：17
页码：5342-5347
DOI：10.1073/pnas.1503082112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceAfter the Apollo and Luna missions, which were flown about 40 years ago, the Moon was explored only from orbit. In addition, no samples were returned from the young and high-FeO and TiO2 mare basalt in the northern Imbrium basin. Such samples are important to understand the formation and evolution of the Procellarum KREEP [potassium (K), rare earth elements (REE), and phosphorus (P)] terrain, a key terrain highly enriched in radioactive nuclides. The Chang'e-3 mission carried out the first in situ analyses of chemical and mineral compositions of the lunar soil and ground-based measurements of the lunar regolith and the underlying basalt units at this specific site. The lunar regolith layer recorded the surface processes of the Moon, whereas the basalt units recorded the volcanic eruption history. We report the surface exploration by the lunar rover Yutu that landed on the young lava flow in the northeastern part of the Mare Imbrium, which is the largest basin on the nearside of the Moon and is filled with several basalt units estimated to date from 3.5 to 2.0 Ga. The onboard lunar penetrating radar conducted a 114-m-long profile, which measured a thickness of [~]5 m of the lunar regolith layer and detected three underlying basalt units at depths of 195, 215, and 345 m. The radar measurements suggest underestimation of the global lunar regolith thickness by other methods and reveal a vast volume of the last volcano eruption. The in situ spectral reflectance and elemental analysis of the lunar soil at the landing site suggest that the young basalt could be derived from an ilmenite-rich mantle reservoir and then assimilated by 10-20% of the last residual melt of the lunar magma ocean.
