Table T7. Microstructure of plutonic rocks.
| Texture type | Physical state | Plagioclase | Olivine | Pyroxene |
|---|---|---|---|---|
| 1 | Magmatic | No or minor crystal-plastic deformation microstructures (e.g., deformation twins, undulose extinction) | No deformation microstructures ± local undulose extinction and/or local subgrain development | No deformation microstructures |
| a | Random-shape orientation | |||
| b | Preferred-shape orientation | |||
| 2 | Crystal-plastic ± magmatic | <30% fine-grained recrystallized matrix; deformation twins and subgrain boundaries may be present | Common subgrain boundaries and undulose extinction | No deformation microstructures ± minor crystal-plastic deformation microstructures |
| 3 | Crystal-plastic | >30% recrystallized matrix; deformation twins, subgrain boundaries, and undulose extinction common; moderate shape-preferred orientation; strong crystallographic-preferred orientation | Elongated aggregates of neoblasts | Kinked grains; common to extensive recrystallization |
| 4 | Crystal-plastic | Strongly bimodal grain size distribution; localized fine-grained neoblasts, polygonal neoblasts, and sutured neoblasts | Closely spaced subgrain boundaries; pervasive undulose extinction, extensive neoblasts | Bent/Kinked porphyroclasts; localized recrystallization |
| 5 | Semibrittle | Common intracrystalline microfractures associated with very fine grained neoblasts; extensive kinked and deformation twinned grains; pervasive undulose extinction; may contain hydrothermal alteration mineral assemblages | Same as plagioclase | Same as plagioclase |
| 6 | Brittle/Cataclastic | Intra-/Intercrystalline microfractures and cataclastic bands; extensive kinked and deformation twinned grains; pervasive undulose extinction | Same as plagioclase | Same as plagioclase |
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