This study reveals the effects of artificial space-like proton irradiation on three meteorite samples that are Northwest Africa (NWA) 4560 LL3.2 and NWA 5838 H6 chondrite meteorites, as well as the Dhofar (Dho) 007 eucrite. We used low-vacuum scanning electron microscopy (LV-SEM) and Raman Spectroscopy to examine the structure and composition of olivine and pyroxene grains in the meteorites before and after the irradiation events. This article focuses on the strongest and most intense irradiation, which was performed by protons up to 12 keV with a fluence value of 1019 ions/cm2 that lasted ~30 h. According to the Raman spectra, significant lattice disruption in all analyzed silicates occurred, and a more extensive amorphous, glassy layer developed under the strongest irradiation conditions. Relative to the second irradiation, peak 1 (820.0 cm−1) shifts slightly negatively (–0.46 cm−1) with a small FWHM increase (+0.88 cm−1), while peak 2 (850.3 cm−1) shifts positively in both parameters (+0.40 and +4.04 cm−1) in NWA 4560 olivines. In NWA 5838 olivines, both olivine peaks (820.5 and 850.8 cm−1) shift positively (+7.40 and +7.90 cm−1) and broaden (+2.75 and +4.29 cm−1). In Dho 007 pyroxenes, peak 1 (997.1 cm−1) shifts positively (+3.01 cm−1) with an FWHM decrease (−0.46 cm−1), peak 2 (669.7 cm−1) shifts slightly negatively (−0.75 cm−1) while broadening strongly (+29.23 cm−1), and peak 3 (327.7 cm−1) shifts positively (+0.86 cm−1) with reduced FWHM (−4.55 cm−1). Three characteristic amorphous bands appear in all examined meteorite silicates, located at ~550–1000 cm−1, ~1100–1700 cm−1, and ~1700–1850 cm−1. Olivines in NWA 4560 and NWA 5838 exhibited similar responses across all irradiation events. In contrast, Dho 007 pyroxenes showed variable compositional changes without a consistent or well-defined pattern in our SEM dataset. The Fo decrease in our experiments likely results from preferential Mg sputtering in the olivine lattice, leading to relative Fe enrichment, similar to but more pronounced than after the first irradiation. Pyroxenes exhibit a comparable response, with Fs and En increasing and Wo sharply decreasing, reflecting preferential Ca loss relative to Mg alongside Fe enrichment. Investigating these processes improves the interpretation of planetary remote sensing data and advances our understanding of planetary surface evolution, while also clarifying how surface materials respond to space environmental conditions.
Rezes et al. (Fri,) studied this question.