Kairui Tai, Yu-Yan Sara Zhao, Yang Li, Zhuang Guo, Jiang Zhang, Chen Li, Ronghua Pang, Jingyan Xu, Jiř ́ Hybler, Xiongyao Li, Jianzhong Liu, Yun Liu
Carbonaceous asteroids are crucial for understanding the early material composition and evolutionary processes of the solar system, as they preserve pristine organic matter and hydrated minerals. While space weathering significantly alters their surface spectral properties, its effects on carbonaceous objects (C-complex asteroids and carbonaceous chondrites) remain debated, hindering accurate remote spectral identification and geological characterization. This study investigated the microstructural and spectral effects of simulated space weathering on carbonaceous chondrites and phyllosilicate-rich materials, offering new insights into the space-weathering processes, alteration mechanisms, and the interpretation of spectral bluing. Pulsed laser simulations were performed on carbonaceous chondrites (Murchison) and phyllosilicates (including serpentine and cronstedtite) at different irradiation conditions of space weathering to simulate micrometeorite impacts. Unirradiated and irradiated samples were analyzed using scanning electron microscopy (SEM), focused ion beam (FIB) sections, transmission electron microscopy (TEM) equipped with electron energy loss spectroscopy (EELS), and visible-near-infrared reflectance (VNIR) spectroscopy to characterize irradiation-induced microstructural, redox, and spectral variations. Weakly and moderately irradiated Murchison developed vesicle-rich amorphous textures associated with VNIR spectral bluing, whereas strongly irradiated Murchison exhibited abundant Fe-rich nanoparticles, including nanophase FeNi (np-FeNi) and nanophase metallic iron (np-Fe0$), and the disappearance of vesicles. In terrestrial cronstedtite, moderate irradiation produced vesicles, wüstite (FeO), and np‑Fe^0 particles, whereas strong irradiation yielded only np‑Fe$^0. Refined EELS analyses of irradiated cronstedtite further revealed localized redox heterogeneity associated with amorphization and nanoparticle occurrence. Pulsed laser irradiation of phyllosilicate-rich materials produces distinct microstructural responses under different irradiation conditions, including vesicle-rich amorphous textures, Fe-rich nanoparticles, and localized redox heterogeneity. Volatile driven vesiculation appears to suppress np-Fe0 formation and contributes to VNIR spectral bluing in hydrated phyllosilicates. These findings provide new microstructural constraints for understanding space-weathering processes and for interpreting spectral bluing or broadly variations in hydrated carbonaceous asteroids and their returned samples.