三郡変成岩の変成相と放射年代に関するノート  [in Japanese] A note on metamorphic facies and radiometric ages of the Sangun metamorphic rocks  [in Japanese]

Correlating the radiometric ages with the grades of metamorphic rocks obtained from the areas hitherto considered to be parts of the Sangun glaucophanitic belt, Southwest Japan, no systematic relation is observed between both features. On the other hand, the radiometric ages are roughly classified into two groups: a) 310-240 Ma and b) 230-120 Ma. The former is of rocks associated closely with serpentinite in an tectonic belt stretching along the northern marginal part of the principal Sangun area. The tectonic belt is considered to be the western extension of the Hida marginal belt and is separated geologically from the Sangun. The latter group of ages shows a wide range extending over 110 million years. A part of these younger ages are inferred to have been resulted from thermal effects due to later granitic intrusions.