SPA Basin Lunar Mantle Samples

More Reduced Farside Mantle

Basaltic fragments returned by Chang'e-6 from the lunar farside reveal a more reduced mantle beneath the SPA basin, providing key samples for understanding lunar asymmetry.

Yang, Wei · Zhang, Di · Hao, Jialong · Mitchell, Ross Nelson · Jia, Lihui · Wu, Shitou · Gu, Lixin · Tang, Xu · Tian, Hengci · Junling, Pei · Lin, Yangting · Li, Xianhua · Wu, Fu yuan

Nature Communications 2025

Specifications

Oxygen fugacity

{'zh': '-1.93', 'en': '-1.93'} ΔIW

Number of samples

{'zh': '23', 'en': '23'}

Advantages

Farside mantle more reduced

First direct measurement of farside mantle oxygen fugacity, averaging ΔIW −1.93, about 1.1 log units lower than the nearside, directly demonstrating hemispheric asymmetry in lunar mantle redox state.

High-precision multi-method

Both spinel V oxybarometer and pyroxene Eu oxybarometer were applied to the same samples, yielding consistent results and enhancing reliability.

Pinpoints asymmetry origin

Proposes two mechanisms: nearside oxidation by more Fe sinking into the core due to asymmetric magma ocean crystallization, and farside reduction by S2 and CO degassing during the SPA impact, guiding future research.

Applications

• Lunar Science：First direct constraint on farside mantle oxygen fugacity to test lunar magma ocean models and mantle asymmetry hypotheses.
• Planetary Geology Samples：Conduct in-situ geochemical analysis on first farside basaltic samples to reveal regional mantle properties.
• High-precision Oxygen Fugacity Analysis：Apply spinel V and pyroxene Eu oxybarometers for high-precision cross-validation on precious farside samples.