岩手縣宮守地方における花崗閃緑岩による超鹽基性岩類の變成現象について : 透輝石・角閃石岩の變成現象

抄録

Ultrabasic rocks exposed in Miyamori district, 16km E of Hanamaki-machi, Iwate Prefecture, is intruded by granodiorite on its western side., The metamophic effect of the acid intrusive is seen in a zone about 24km wide along the contact., In this zone, diopside-hornblende rock, a member of the ultrabasic complex, occurs as parallel dikes cutting serpentinized dunite., In the latter rock, porphyroblasts of tremoliteactinolite have been formed by the metamorphism, while the former rock has been converted to the following rock types : 1, Grossularite-basic plagioclase rock (sometimes with epidote and hedenbergite) 2, Bluish green amphibole-biotite rock 3, Biotite-bluish green amphibole-acidic plagioclase rock The first type is characterized by richness in Ca, the second by that in K, Mg and Fe, while the third by that in Na, Fe and Mg (see Fig 6)., It is concluded that these changes have been brought about by combined metasomatism and metamorphic differentiation ; Al, K, Na and Si having been introduced to the diopside-hornblende rock while Fe, Mg and Ca having migrated within the same rock mass.,