Fig. 3: Oriented photomicrograph and electron backscatter diffraction (EBSD) analysis of the micro-shear zone within the micro-sheared metachert.

a The alternation of coarse quartz ribbons and micro-shear zones, along with pronounced foliation consisting of elongated phengite (Phg) and glaucophane (Gln). White arrowheads indicate the microboudinage of Gln; crossed polarized light. b Typical subgrain rotation recrystallization (SGR) of quartz (Qz) occurs within the micro-shear zone, which is defined by elongated phengite aggregation (E52 site A); crossed polarized light. c Coarse quartz ribbons intersected by foliation-parallel micro-shear zones. Microboudinage of Gln is shown by white arrowheads; crossed polarized light. d Misorientation to mean grain orientation (Mis2mean) maps showing the intragranular misorientation patterns of quartz. e Misorientation traverses along the A–A’ and B–B’ profiles (locations marked in part d). The A-A’ misorientation profile angle across the subgrain boundaries in larger relict grains is associated with progressive jumps below 6°, while the abrupt alternation of misorientation angle from grain boundaries between small recrystallized grains ranges from 20–60° along the B-B’ profile. f, g Quartz c-axis pole figures, misorientation axis distributions (2–10°), crystallographic vorticity axis (CVA) analysis, and misorientation angle distributions (MAD) are shown for the regions of the micro-shear zone and coarse quartz ribbons in (e). h Grain size distributions of micro-shear zones from micro-sheared metacherts across the studied metachert block. See Fig. 2 for the legend.