Abstract
Ryoke gneisses in Tomiyama were intruded by granitic veins several to 30cm in width. Folded and boudinaged veins were emplaced around 93-90 Ma, and non-deformed veins c.85 Ma. Ductile deformation continued beyond 93-90 Ma and ended before 85 Ma. Quartz in the non-deformed veins has chessboard-patterned SGBs, similar to those in deformed veins. The density of SGBs in the non-deformed veins is much lower than in the deformed veins, and is compatible with that in the late-stage two-mica granite, emplaced c.74 Ma. A period of thermal inactivity is thus envisaged before the reheating of the area by the two-mica granite. Uplift subsequent to the final plutonism may have produced minor deformation, expressed as chessboard SGBs in quartz grains in non-deformed veins and the two-mica granite.
