R8: Metamorphic rocks and tectonics

[R8-03] Constraint on deformation temperatures of the Karasaki mylonite, western Shikoku

*Yoshihiro Nakamura¹, Kazuhiro Miyazaki¹ (1. Geological Survey of Japan, AIST)

Keywords:Karasaki mylonite, Sanbagawa metamorphic rock, EBSD

Karasaki mylonite preserves asymmetric type I crossed girdles with maxima around poles to the rhomb planes, which have small opening angles between 41° and 57°. The type I crossed girdle pattern in the Sanbagawa metamorphic rock has similar opening angle of 51°. The quartz c-axis opening angles indicate deformation temperatures of 330–440 ± 50 °C, and 400 ± 50 °C based on quartz opening angle thermometry. Estimated deformation temperatures are well consistent with peak temperatures of 421 ± 41 ℃ determined from RSCM thermometry.