Fig. 3: Vesicles and classification of lunar agglutinates.
From: Saturation of space weathering in shaping lunar regolith particle morphology
a Void ratios and internal regular vesicles fraction (Ir) of selected larger agglutinates from CE5 (red) and CE6 (blue) lunar samples. eCE5, eCE6 and eA17 denote the average void ratios of these agglutinates, with eCE5 significantly higher than eCE6 and eA17, suggesting more intense micrometeorite bombardment at the CE6 and Apollo 17 site. The average Ir values of the two groups are nearly identical, as indicated by vertical solid lines in the upper kernel density plot. Pentagons indicate average Ir and void ratios of numerous bulk soil agglutinates for CE5 (red) and CE6 (blue), with error bars representing standard deviations. The higher Ir values observed in CE5 agglutinates may be attributed to differences in internal structure. b Linear regression between Ir and fragment content (Fr) for selected larger agglutinates, yielding a strong inverse correlation (grey shaded region, 95% confidence interval). As Ir increases, fragment content decreases, reflecting enhanced vitrification and glass-dominant textures. Conversely, lower Ir values correspond to increased fragment content and breccia-like structures. Based on Ir values, agglutinates are classified into three types: high fragment content agglutinates, medium fragment content agglutinates, and low fragment content agglutinates. These classifications are also indicated in (a). In c, d, f, representative examples of agglutinates from each type, labeled as CE6AggHF, CE6AggMF, and CE6AggLF, are marked with light blue symbols in (a, b). The left panels show the CT radiographs, while the right panels present 3D reconstructions of internal structures: irregular vesicles (red), regular vesicles (blue), and fragments (yellow). These visualizations confirm the statistical trends observed in (b). e Enlarged view of vesicles within agglutinates, illustrating that vesicles formed adjacent to fragments are more irregular due to mechanical constraint, while vesicles developed within the glassy matrix are more regular.
