北海道幌満産かんらん岩中の斜長石について On the Plagioclase Feldspar in the Peridotite Mass, in the Horoman Area, Hokkaido
At the southern end of the Hidaka plutonic and metamorphic belt, a large ultrabasic intrusive mass occurs. In this ultrabasic mass, various kinds of rock facies exist, such as dunite, peridotite, plagioclase peridotite and gabbro. In gabbro and plagioclase peridotite, plagioclase is one of the essential minerals in some cases and of the accessary minerals in other cases. The plagioclase feldspar is labradorite or bytownite and contains a little Or-molecule. X-ray powder diffraction patterns of the plagioclase feldspar show that most of them are not of the typical low-temperature form. From this fact, it is tho.ught that the plagioclase feldspar grew under the comparatively high-temperature condition.
地球科学 21(6), 10-13, 1967