Long-term reduced lunar mantle revealed by Chang’e-5 basalt

• Published in: Nature communications Vol. 15; no. 1; pp. 8328 - 9
• Main Authors: Zhang, Huijuan, Yang, Wei, Zhang, Di, Tian, Hengci, Ruan, Renhao, Hu, Sen, Chen, Yi, Hui, Hejiu, Lin, Yanhao, Mitchell, Ross N., Wu, Shitou, Jia, Lihui, Gu, Lixin, Lin, Yangting, Li, XianHua, Wu, Fuyuan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.09.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 140/58; 147/135; 704/445/209; 704/445/431; Basalt; Cooling rate; Crystallization; Degassing; Earth mantle; Fragments; Fugacity; Geophysics; Humanities and Social Sciences; Lunar evolution; Lunar mantle; Mars; Moon; multidisciplinary; Olivine; Oxidation; Oxygen; Planetary evolution; Planetary mantles; Redox properties; Science; Science (multidisciplinary); Thermal evolution; Vanadium
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-52710-x

The redox state of a planetary mantle affects its thermal evolution. The redox evolution of lunar mantle, however, remains unclear due to limited oxygen fugacity ( f O 2 ) constraints from young lunar samples. Here, we report vanadium (V) oxybarometers on olivine and spinel conducted on 27 Chang’e-5 basalt fragments from 2.0 billion years ago. These fragments yield an average f O 2 of ΔIW -0.84 ± 0.65 (2σ), which closely aligns with the Apollo samples from 3.6–3.0 billion years ago. This temporal uniformity indicates the lunar mantle remained reduced. This observation reveals that the processes responsible for oxidizing mantles of Earth and Mars either did not occur or had negligible oxidizing effects on the Moon. The long-term reduced mantle may lead to a distinctive volatile degassing pathway for the Moon. It could also make the lunar mantle more difficult to melt, preventing internal heat dissipation and consequently resulting in a slow cooling rate. The lunar mantle may have remained reduced, according to the oxygen fugacity of 2.0 Ga Chang’e-5 basalt that is similar to 3.6 − 3.0 Ga Apollo basalts and pyroclastic glasses.