Abstract Northwest Africa (NWA) 7034 and its paired meteorites represent polymict regolith breccias derived from the ancient Martian crust. We employed micro‐X‐ray diffraction and Raman spectroscopy to quantitatively assess impact‐induced metamorphism in plagioclase and alkali feldspar. Strain‐related mosaicity (SRM) was measured via full width at half maximum in the Debye ring or chi (χ) dimension (FWHMχ) from 2D XRD images. A total of 149 plagioclase and 21 alkali feldspar grains were analyzed. Plagioclase exhibits FWHMχ values from 0.5° to 10.9°, and alkali feldspar shows a range of 2.1°–9.7°. Plagioclase grains record peak shock pressures from 0 GPa (unshocked) to 28–30 GPa based on calibrations for experimentally shocked andesine. Approximately 26% of grains show no detectable shock deformation (<1.0 GPa), while ∼4% preserve evidence of severe shock (>21.0 GPa), indicative of exposure to at least moderate shock metamorphism prior to ejection from Mars. Alkali feldspar records higher apparent peak pressures, possibly spanning 4.7–28.5 GPa. Martian crustal minerals experienced highly heterogeneous shock effects, which highlights the complex and varied impact histories of feldspar minerals during the impact‐induced brecciation process. Pressure differences between plagioclase and alkali feldspar may reflect distinct source regions, pre‐lithification shock events, or differing shock responses. This study highlights the importance of multi‐mineral analytical approaches to enhance the accuracy of shock pressure quantification in Martian regolith breccias and to reconstruct the planet's impact processes. This methodology should also be applied to other extraterrestrial samples to characterize shock effects across planetary bodies in the solar system.
Plain Language Summary Martian “Black Beauty” meteorites, ejected to Earth as regolith breccias, represent our only available samples of the Martian surface regolith until future sample‐return missions. We studied how impacts altered the crystal structures of their dominant feldspar minerals (plagioclase and alkali feldspar) using X‐ray diffraction and Raman spectroscopy to decode their shock histories on the Martian surface. Plagioclase crystals show different impact damage, ranging from unshocked to highly shocked. About 26% of these grains were barely affected (<1 GPa), while only 4% were heavily damaged (>21 GPa), suggesting intense pre‐ejection impacts. Alkali feldspars recorded higher apparent peak shock pressures (∼4.7–28.5 GPa). This heterogeneous distribution highlights the complex and varied impact histories experienced by feldspar minerals. This pressure difference could suggest that plagioclase and alkali feldspar come from distinct Martian regions or that these two minerals respond differently to shock. To more accurately estimate the intensity of ancient impacts and reconstruct Mars's impact history, we recommend analyzing multiple minerals together, as individual types react uniquely to similar impacts. The non‐destructive pressure estimation methods can also study future returned Martian samples and rocks from other planetary bodies, such as the Moon or asteroids, to uncover collision stories across the solar system.
Key Points 149 plagioclase and 21 alkali feldspar grains from various Martian breccia pairings were analyzed using micro‐XRD to quantify the shock level Plagioclase and alkali feldspar exhibit broad peak shock pressure ranges, indicating diverse impact histories on the Martian crust Around 26% of plagioclase grains were unshocked (<1.0 GPa), ∼4% were highly shocked (>21.0 GPa), and ∼70% showed low to moderate shock
