¹Chengyuan Wang,¹Yi-Gang Xu,¹Le Zhang,¹Zhiming Chen,¹Xiaoping Xia,¹Mang Lin,¹Feng Guo
Earth and Planetary Science Letters 693, 118770 Link to Article [https://doi.org/10.1016/j.epsl.2024.118770]
¹State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
Copyright Elsevier

The lunar magma ocean (LMO) hypothesis predicts that the uppermost mantle (∼60–100 km) is composed of ilmenite-bearing cumulate (IBC), which may have sunk deeply due to gravitational instability. However, the extent to which this process restructured the lunar mantle and influenced mare volcanism remains unclear. Here, we approach this issue by examining pyroxenes in Chang’E-5 (CE5) basalts and petrological modeling. We show that the low Mg# and negative anomalies in Ti and Ta of CE5 basalts cannot be produced by extensive fractionation of peridotite-derived low-Ti basalts, but were most likely formed through partial melting of a shallow (< 100 km) IBC pyroxenite source. This model is also applicable to the ∼3.0 Ga lunar basaltic meteorites. The increasing involvement of IBC sources in young lunar magmas, also revealed by the remote-sensing data, implies an inefficient gravitational restructuring process during the late LMO stage and provides new insights into the thermochemical state of the lunar interior.