EBSD map analysis for antigorite deformation micro-textures related to dislocations: Implications for the effect of antigorite crystal structure on plastic deformation

21 The identification of dislocations and associated Burgess vectors in minerals is important to 22 discuss the mechanisms of crystal plastic deformation of rocks. Observation of dislocations is 23 normally carried out using transmission electron microscopy (TEM) . However, the necessary 24 sample preparation and observation can be challenging in particular for hydrous minerals that 25 are sensitive to beam damage. In addition, the spatial scale at which TEM can be used to observe 26 dislocations is limited, making it difficult to evaluate the process of bulk -rock deformation. 27 Recently, the improved accuracy and indexing rate in Electron Backscatter Diffraction (EBSD) 28 mapping and the ease of analyzing mapping data using a toolkit for analysis provided in 29 programming software have made it possible to observe the microstructural features related to 30 dislocations using EBSD measurements, such as small misorientations less than a few degrees 31 of angular differences within a single grain. In this study, we examine how EBSD observations 32 Accepted in JMPS Pre-proof Journal of Mineralogical and Petrological Sciences, J–STAGE Advance Publication, February 3, 2026 © 2026 Japan Association of Mineralogical Sciences This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), which permits non-commercially distribute and reproduce an unmodified in any medium, provided the original work is properly cited. https://doi.org/10.2465/jmps.250814 2 of natural antigorite-rich serpentinite samples can be used to derive information about the nature 33 of dislocations and associated antigorite deformation mechanisms. In particular, we focused on 34 the effect of different lengths in the crystal undulations, expressed as M- and m-values, of 35 antigorite on the deformation process es and the resulting crystal preferred orientation (CPO) 36 patterns of antigorite in antigorite schists samples. The resulting antigorite CPOs are all like the 37 B-type CPO patterns that have been widely reported from natural antigorite schists regardless 38 of the wavelength of the curved antigorite crystals. However, misorientation analyses using the 39 EBSD maps suggest dislocations characteristic of the [100](001) slip system , responsible for 40 A-type CPO formation, are more common in antigorite -rich serpentinites with shorter 41 wavelengths, whereas dislocations characteristic of the [hk0](001) slip systems, responsible for 42 G-type CPO formation, are more common in those with longer wavelengths. Therefore, the 43 dislocation microstructures observed in this study do not provide evidence that the B-type CPO 44 was formed by dislocation creep. However, these dislocation microstructures may preserve 45 evidence of different deformation stages before and after the formation of the B-type CPO. This 46 implies that, as M- and m-values tend to decrease under high -pressure conditions, A- and G-47 type CPOs are likely to form in deeper and relatively shallower domains, respectively. These 48 results suggest the strength of schistosity, grain shape, and CPO strength in ductilely deformed 49 antigorite-rich serpentinite s may be affected by differences in the dominant deformation 50 mechanisms and dislocation microstructures influenced by the wavelength of antigorite. 51 52