241-8 Insights into Lunar Evolution from Basaltic Breccias: the Mineralogy and Petrology of Dominion Range (DOM) lunar meteorite 18543

Session: Petrology, Volcanology, and Mantle Plumes across the Solar System, Part I

Presenting Author:

Claire McLeod

Authors:

McLeod, Claire Louise¹, Schweitzer, Alex R.², Gawronska, Aleksandra J.³, Lytle, Marion⁴, Shaulis, Barry⁵, Loocke, Matthew Phillip⁶

(1) Miami University, Oxford, OH, USA, (2) Miami University, Oxford, OH, USA, (3) Catholic University of America, Washington DC, Washington DC, USA, (4) Miami University, Oxford, OH, USA, (5) University of Arkansas, Fayetteville, AR, USA, (6) Louisiana State University, Geology and Geophysics, Baton Rouge, LA, USA,

Abstract:

Lunar meteorites provide critical insights into the Moon’s geological evolution and extend our understanding of differentiated planetary bodies in the inner Solar System. During the 2018–2019 Antarctic Search for Meteorites (ANSMET), eight lunar meteorites were recovered from the Dominion (DOM) Range, the first such finds since 2001. This study focuses on thin section -9 of DOM 18543, a basaltic regolith breccia.

DOM 18543,9 is clast-poor, containing gabbroic clasts in addition to one FAN-dominated (anorthositic granulite) microbreccia clast. All clasts are embedded within a glassy matrix. Mineral fragments include clinopyroxene, plagioclase, and olivine, with accessory Fe-Ti oxides, sulfides, and phosphates. The studied section is ~75% rimmed by a vesiculated, glassy fusion crust. Notable features include melt veins (up to 80 μm wide), abundant glass spherules (up to 400 μm), and 3-phase symplectites comprising Fe-rich olivine, clinopyroxene, and silica.

Electron Probe Microanalysis (EPMA) reveals that pyroxenes (n=135) range from augite to pigeonite compositions. Orthopyroxenes are rare. Olivines (n=28) are dominantly fayalitic (Fa_85.0-98.7), with two magnesian grains (Fa_49.5,Fa_36.1). Plagioclase feldspars (n=67) are mostly anorthitic (An_92.9–99.2), with a few bytownitic grains (An_85.8–89.1). Plagioclase compositions within the FAN-dominated microbreccia clast are tightly constrained to An_96-97.

Fe/Mn ratios in pyroxenes (avg. 0.015±0.005) and olivines (avg. 0.012±0.002) confirm a lunar provenance. The meteorite’s mineralogical and chemical traits align closely with other 2018–2019 DOM lunar finds, consistent with their pairing.

To infer potential source regions, mineral chemistries were compared with Apollo samples, Chang'e 5 and 6 samples, and select lunar meteorites. Pyroxenes in DOM 18543,9 exhibit Mg/(Mg+Fe) vs Ti/(Ti+Cr) ratios consistent with low-Ti basalts, and similar to those of Apollo 12, 15, (±17), and the Chang'e 6 basalts. Fusion crust wt. % FeO–Al₂O₃ systematics indicate a mare-derived origin, rather than KREEP or FAN, and are consistent with previous work on the 2018-2019 lunar DOM suite (18509, 18678). Major element glass characteristics (e.g., wt. % FeO vs. wt. % TiO₂) from the DOM 18543.9 fusion crust and melt pockets indicate a compositional similarity with the Yamato 793169, Asuka 881757, Miller Range 05035, and Meteorite Hills 01210 (YAMM) meteorite suite. This could suggest a source from cryptomare deposits near the Schiller-Schickard region on the Moon’s southwestern nearside, as previously proposed.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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