Long-term reduced lunar mantle revealed by Chang'e-5 basalt
Huijuan Zhang1,2, Wei Yang3, Di Zhang1
1Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.
Nature Communications
|September 27, 2024
Summary
The lunar mantle has remained consistently reduced over billions of years, unlike Earth and Mars. This sustained low oxygen fugacity (fO2) influences the Moon's thermal evolution and volatile release.
Area of Science:
- Planetary Science
- Geochemistry
- Lunar Geology
Background:
- The redox state of a planetary mantle is crucial for its thermal evolution.
- Understanding the Moon's mantle redox evolution is limited by scarce young sample data.
Purpose of the Study:
- To determine the oxygen fugacity (fO2) of the young lunar mantle using vanadium oxybarometers.
- To investigate the long-term redox evolution of the lunar mantle.
Main Methods:
- Analysis of vanadium (V) in olivine and spinel.
- Utilizing 27 Chang'e-5 basalt fragments dating back 2.0 billion years.
- Oxygen fugacity (fO2) measurements using vanadium oxybarometers.
Main Results:
- The Chang'e-5 samples indicate an average fO2 of ΔIW -0.84 ± 0.65.
- This fO2 is comparable to older Apollo samples (3.6-3.0 billion years ago).
- The lunar mantle has remained consistently reduced over geological time.
Conclusions:
- The Moon's mantle has not undergone significant oxidation events seen on Earth and Mars.
- A persistently reduced lunar mantle suggests a unique volatile degassing pathway.
- This reduced state may impede mantle melting, leading to slower cooling and internal heat retention.
