Regional occurrence of orthopyroxene‐bearing basic rocks in the Yanai district, southwest Japan: Evidence for granulite‐facies Ryoke metamorphism

Abstract

Abstract The present paper is reporting on the regional occurrence of orthopyroxene‐bearing basic rocks from the Ryoke Metamorphic Belt in the Yanai district, southwest Japan. Their localities are confined to the highest‐grade zone of the area (i.e. the garnet–cordierite zone, where garnet coexists with cordierite, K‐feldspar and biotite in pelitic rocks). Orthopyroxene coexists with quartz and hydrous minerals such as biotite, cummingtonite and hornblende, and in some cases with clinopyroxene, suggesting that the highest grade of the Ryoke metamorphism reached a low‐temperature subfacies of the granulite facies, contrary to the upper amphibolite facies as previously asserted.