125 Lunar Science and Exploration in the Artemis Era

Current and anticipated science return in the areas of geology, composition, and interior of the Moon from current lunar-focused studies and upcoming payloads expected to land on the Moon in the next decade.

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 214C

Beyond Pristinity: Rethinking Lunar Samples and Their Role in Planetary Evolution

Paper number: 125-2
Program: Technical Sessions
Time: 1:50 PM – 2:05 PM

Authors

Abstract

Lunar samples labeled “pristine” have long served as the foundation for models of planetary differentiation and the magmatic evolution of the Moon. Because Earth’s earliest history has been obscured by plate tectonics and surface reworking, lunar materials have also been critical to reconstructing early Earth evolution, including the role of large impacts thought to have shaped it. However, the concept of “pristine” is increasingly debated, as traditional criteria—based on factors like whole-rock texture, mineralogy, and element abundances—may overlook extensive impact-related reworking that requires new analytical strategies to detect. This challenge strikes at the core of planetary geochronology: How can we distinguish primary magmatic signatures from secondary overprints in ancient samples? 

To address this fundamental challenge, we developed a new approach integrating experimental petrology, geochemistry, and geochronology. Using Al-in-zircon partitioning in Apollo samples, we directly test chemical equilibrium between minerals and their host melts at the grain scale—allowing a more rigorous assessment of pristinity than bulk-sample criteria. We analyzed glasses in direct contact with zircons and large glass inclusions within zircon interiors—intimate relationships where the glass should represent fossilized melt from which the zircons crystallized. Instead, we found systematic disequilibrium: glass compositions match impact-generated melts while zircons preserve evidence of crystallization from entirely different parent magmas. This mismatch reveals that even the most ostensibly pristine samples have experienced complex post-crystallization histories, including multiple magmatic episodes and extensive impact reworking. 

These findings challenge the foundation of how pristinity is defined and interpreted in planetary samples. As we enter a new era of sample return from the Moon, Mars, and asteroids, addressing the complexity revealed in legacy lunar materials becomes critical. This will require not only precise dating but also interpretive frameworks capable of resolving overprinted, multistage histories. Our results show that integrating experimental petrology, geochemistry, and geochronology offers a powerful path forward. Expanding and refining such approaches will be essential for strengthening planetary geochronology—and ensuring that the scientific return from future missions is both rigorous and revealing.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412109

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