Masao Gorai

Masao Gorai
Masao Gorai
Born	1916; Fukushima Prefecture, Japan
Died	February 4, 2002
Residence	Haramachi-Shi, Japan
Nationality	Japanese
Alma mater	Tokyo University of Education
Known for	Plagioclase twin (Gorai) method, Expanding Earth
	Scientific career
Fields	Geologist, petrology
Institutions	Tokyo University of Education

Masao Gorai (牛来正夫, 1916 – 4 February 2002) was a Japanese geologist and petrologist, known for his work on feldspar twinning and the origin of granitic rocks and, in his later career, for his support of the Expanding Earth concept of global tectonics. He spent his career at the Tokyo University of Education, where he devoted his research to the study of magmatism and the evolution of the Earth.

Biography

Gorai was born in 1916 in Fukushima Prefecture, Japan, and graduated from the Tokyo University of Education, where he later became a professor. He dedicated his career to the study of magmatism and Earth evolution. He was one of the three founding members of the Geological Collaboration Association of Japan (CHIDANKEN). He died on 4 February 2002.

Scientific contributions

Gorai's paper on the plagioclase twin now associated with his name first appeared in a Japanese journal in 1947; petrologists elsewhere had to wait until 1951, when the work was published in American Mineralogist as "Petrological studies on plagioclase twins." The method he proposed distinguished between the twinning of plagioclase in igneous and metamorphic rocks, and so enabled a distinction to be drawn between igneous and metamorphic granites, a topic of intense debate in the 1940s and 1950s.

In addition to this classic paper, Gorai published another influential paper in 1951 as a clear antithesis to Bowen's primary basaltic magma theory, emphasizing the role of the interaction of crustal and mantle material in the process of magma generation. In the middle 1950s he changed his view of granite genesis from the granitization of sedimentary rocks to mantle derivation, on the basis of a new study of lead isotopes. He inaugurated and developed an isotopic petrology laboratory in his department and carried out pioneering studies based on both Rb–Sr and Sm–Nd isotopic systematics, helping to train a new generation of petrologists and isotope geochemists.

Gorai's first series of Japanese textbooks, Petrogenesis of Igneous Rocks, appeared in 1955–1958. The books developed his ideas of magma generation through mantle–crust interaction and encouraged many young Japanese researchers. Gorai was in agreement with Wegener's continental drift theory but disagreed with extending it into much earlier times. He was inclined more toward the concept of the Expanding Earth, which he considered responsible for the principal dispersion of the supercontinent in Cretaceous time. His textbooks after the 1970s are based on this idea.

In his own account of this later work, Gorai wrote that he had "been investigating the tectonic and enigmatic evolution of the Earth" and had come to believe that "the most fundamental motive force responsible for such evolutional processes is the Earth's expansion, which might have happened through the inversion of super-dense phases deep in the Earth into ordinary molecular phases." He added that he had been "much inspired by several forerunners of the Earth's expansion hypothesis, especially by the excellent book of Dr. S. W. Carey, published in 1976."

External links

Obituary: Masao Gorai (1916–2002), Gondwana Research (Gondwana Newsletter Section), V. 6, No. 4, pp. 938–939, 2003, International Association for Gondwana Research, Japan.