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Akiho Miyashiro 1921-2008

Miyashiro Akiho Miyashiro dominated the study of metamorphic geology throughout a long career. Like his predecessors Alfred Harker and Frank Turner he summarised his vast knowledge in a series of textbooks and was pleased when his publisher agreed that his final book Metamorphic Petrology (1994) would have the same title that Turner had used in 1968. The scope of Miyashiro’s book was wider and his exposition of metamorphic thermodynamics and the facies classification clear, consistent and convincing but less dogmatic than Turner’s. Between them, his textbooks established the modern approach to metamorphism and metamorphic rocks that superseded Harker’s book Metamorphism (1932).

He gained his reputation while a graduate student at Tokyo University by classic field and petrographic studies of metamorphosed basic igneous rocks of the Abukuma Plateau of Japan, partly while working with Fumiko Shido whom he later married. He coined the name ‘metabasites’ for these rocks. Their accompanying metapelites display a different zonal sequence from the classic zones of the Grampian Highlands of Scotland described by Barrow and Harker, and this formed the basis of his paper on metamorphic belts (1961) that used metamorphism of Japanese basement rocks as a key example linking progressive regional metamorphic sequences with ancient geothermal gradients. He related contrasting metamorphic belts to the thermal structure of island arcs above what were subsequently recognised as subduction zones. His demonstration that patterns of regional metamorphism reflect the geodynamics of large-scale structures like island arcs establishes him as one of the founders of plate tectonics.

He could be controversial. In 1979, he challenged the universally accepted opinion that the basalts and metabasites of the Troödos Ophiolite of Cyprus were typical MORB, erupted or intruded at an ancient oceanic ridge. Miyashiro pointed out that the majority of published analyses had island arc basalt (IAB) compositions and was immediately attacked in print for pronouncing about the geology of a country he had not visited. Subsequent research has proved him right because the Upper Pillow Lavas of Troödos are IAB as he said, and only the Lower Pillow Lavas are MORB. Those who were quick to criticise should have paid more attention to his extensive knowledge of basic rocks in a modern island arc and his publications about dredged oceanic basalts.

Although on first meeting he appeared austere and reserved, he was warm-hearted and a loyal friend. I got to know him when I was invited to act as scientific editor of his book Metamorphism and Metamorphic Belts (1973). He was scrupulous about accuracy and had fallen out with his publishers’ professional editors because they lacked scientific understanding and criticised the correct English grammar he had mastered by great effort. We worked well together once I had met his exacting scientific standards and agreed that he was usually right about grammar, and I am proud that he incorporated a few of my suggestions in the book. He supplemented my editing fee by a far more generous donation from his royalties, because he knew I was a recently-appointed university lecturer with a wife and three children and needed the money. His publisher had the same problem 20 years later with Metamorphic Petrology and asked me once again to assist in producing an equally excellent book.

My colleague at China University of Geosciences (Wuhan), Prof Tim Kusky, who was Miyashiro’s undergraduate and postgraduate student at the State University of New York at Albany, has similar memories. “Many students were reluctant to visit Akiho in his office with questions about the course, because his office was often bare except for a meticulously organised bookshelf, and two simple chairs, where he would sit and face the student with their questions. As a student, I would enter with questions, and Akiho would first probe my understanding of what he taught to see if it was comprehended before he would answer, and his answers were often in the form of leading me through a chain of thinking that would lead to the correct answer.”

He continued to live at Albany after he retired, keenly followed developments in metamorphic geology and was working on a book about non-equilibrium thermodynamics in metamorphism at the time of his death. He regularly sent me articles and books to improve my lectures. He and Fumiko cultivated a beautiful Japanese garden and he sent me photographs of plants and wildlife every year. They enjoyed travelling and mountain walking and his death in July 2008 was caused by a fall while walking in a country park on the Helderberg escarpment near his home.

Roger Mason, with grateful thanks to Tim Kusky