抄録
Staurolite-bearing pelitic rocks have been newly found at two locations in the western Hitachi district, southernmost Abukuma Plateau, as predicted by Uruno based on his river sand survey. One is a sheared pelitic schist occurring next to the Tamadare metamorphics near Zoso. It is composed mainly of sillimanite, cordierite, biotite, muscovite, plagioclase and quartz with metastable andalusite. Staurolite is relic, being entirely enclosed in cordierite. The other is a pelitic xenolith in the Nishidohira cortlandtite mass, consisting mainly of sillimanite, garnet, biotite, plagioclase, and quartz. Staurolite occurs together with sillimanite and spinel as inclusions in idiomorphic, normal-zoned plagioclase. Thus, staurolite in these rocks is a relict enclosed in other minerals, although the matrix mineral assemblages are distinctly different between these two. Staurolite is additionally found in the Nishidohira andalusite-kyanite-sillimanite porphyroblastic pelitic gneisses. In this case, staurolite occurs as inclusions in garnet and plagioclase, being occasionally associated with kyanite, sillimanite and muscovite.
