^1,2Runwu Li, ^1,2Ming Tang, ¹Jiaxi Wang
Earth and Planetary Science Letters 671, 119650 Link to Article [https://doi.org/10.1016/j.epsl.2025.119650]
¹Key Laboratory of Orogenic Belt and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871, China
²Research Institute of Extraterrestrial Material (RIEMPKU), School of Earth and Space Sciences, Peking University, Beijing 100871, China
Copyright Elsevier

The samples returned by the recent Chang’e-5 (CE-5) mission confirmed active lunar magmatism at least two billion years ago, which challenged the long-held view of an inactive Moon through much of its lifespan. However, the origin of this extended lunar magmatism remains mysterious. The CE-5 lunar soil and basalt fragments exhibit a strong fractionation between middle and heavy rare earth elements, a phenomenon rarely observed in the Apollo samples. We confirm this fractionation as a primary magmatic signature with measurements of the pyroxenes. By coupling phase equilibria modeling and element partitioning calculations, we show that this fractionation can only be produced if the magma source contained ∼5-10% garnet at a minimum depth of ∼700 km. We suggest the primary CE-5 magma may have originated from the lunar lower mantle. For melting to occur, one possibility is that convection may have been sustained in the deep lunar mantle until at least two billion years ago. Alternatively, the CE-5 magma may have tapped the melt-bearing layer near the core, as indicated by recent seismic observations.

¹Sarah Joiret, ^1,2Alessandro Morbidelli, ³Rafael de Sousa Ribeiro, ⁴Guillaume Avice, ⁵Paolo Sossi
Eartha and Planetary Science Letters 671, 119625 Link to Aricle [https://doi.org/10.1016/j.epsl.2025.119625]
¹Collège de France, Université PSL, 75005 Paris, France
²Laboratoire Lagrange, Université Cote d’Azur, CNRS, Observatoire de la Côte d’Azur, Boulevard de l’Observatoire, 06304 Nice Cedex 4, France
³Sao Paulo State University, UNESP, Campus of Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333 – 6 Pedregulho, Guaratingueta – SP, 12516-410, Brazil
⁴Université Paris Cité, Institut de physique du globe de Paris, CNRS, 75005 Paris, France
⁵Institute of Geochemistry and Petrology, ETH Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland
Copyright Elsevier

Mars finished forming while the solar nebula was still present, and acquired its primordial atmosphere from this reservoir. The absence of a detectable cometary xenon signature in the present-day Martian atmosphere suggests that the capture of solar nebular gas was significant enough to dilute later cometary contributions. By quantifying the mass of cometary material efficiently retained on Mars, we place a lower bound on the mass of the primordial Martian atmosphere. To test the robustness of our conclusions, we use cometary bombardment data from two independent studies conducted within a solar system evolutionary model consistent with its current structure. Our calculations show that, even under the most conservative scenario, the minimal mass of the primordial martian atmospheres would yield a surface pressure of no less than 2.9 bar. Such a massive nebular envelope is consistent with recent models in which atmospheric capture is strongly enhanced by the presence of heavier species on Mars – due to outgassing or redox buffering with a magma ocean.