¹Dian Ji, ¹Rajdeep Dasgupta
Earth and Planetary Science Letters 690, 120133 Link to Article [https://doi.org/10.1016/j.epsl.2026.120133]
¹Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main Street, MS 126, Houston, TX 77005, USA
Copyright Elsevier

As the youngest returned mare basalt to date, deciphering the petrogenesis of Chang’e-5 (CE-5) basalts could assist us in understanding the late-stage lunar mantle evolution. However, the lithology of the CE-5 mantle is still controversial. Here, we present a joint study of high pressure-temperature major element phase equilibria using laboratory experiments and trace element modeling, and show that garnet is present in the source of young mare basalts on the Moon. Our high-pressure-temperature experiments approaching the multiple saturation point of the putative parental melt compositions of young CE-5 basalt show garnet and clinopyroxene coexisting with the quenched silicate melt. Trace element modeling also confirms that small amounts of garnet in the mantle source are required to reconcile the rare-earth element pattern of the CE-5 basalts, regardless of whether the CE-5 basalts were the direct mantle-melting products or produced through extensive fractional crystallization of a primitive basalt. The existence of garnet in the source either implies that lunar mantle overturn played a crucial role in contributing to the lunar mantle heterogeneity, creating a garnet-clinopyroxenitic mantle source of these young mare basalts that survived the subsequent mantle evolution, or a late-stage process introduced fertile material into the deep mantle, and such geodynamic processes within the lunar interior may have continued until 2 Ga.