R8: Metamorphic rocks and tectonics

[R8-13] An application of Raman geothermometry to carbonaceous materials in metapelites of the Horokanai area in the Kamuikotan metamorphic terrane, central Hokkaido, Japan

*Kosuke Naemura¹, Yushi Nishida¹, Ichiko Shimizu², Yuriko Horie², Syusuke Kinoshita², Takao Hirajima² (1. Iwate University, 2. Faculty of Science, Graduate School of Kyoto University)

Keywords:Kamuikotan belt, Raman thermometry, blueschist, subduction zone

Kamuikotan blueschist exposed at the Horokanai valley display metamorphic zonation consisting of lawsonite dominant Zone-1, transitional Zone-2, and epidote-bg. Zone-3. This study aims to define temperature of each zone by use of Raman geothermometery for carbonaceous materials. We applied geothermometer to 8 metapelites along the Osarunai river at the NW valley and obtained a uniform temperature at ca. 300 ℃. Carbonaceous materials also occur in actinolite rocks whose temperature was ca. 400 °C. Therefore slab surface temperature was 300 °C, which was heated during exhumation.