Earth News This Week

Friday, July 25, 2008

Miyashiro is dead


Akiho Miyashiro, author of "Metamorphism and Metamorphic Belts"dies in an accident

The body of Akiho Miyashiro was found at bottom of 300-foot cliff at Thacher State Park after 36-hour on July25, 2008

Akiho Miyashiro may have wandered off a trail near the Glen Doone Overlook before falling to his death. The cliff he fell over is not near any of the park's 12 miles of marked trails.

"He may have gotten lost and walked over the edge in the dark while trying to find his way back," Albany County Sheriff's Inspector Mark Defrancesco said. "It's a steep, steep drop with a bunch of rocks and a ravine at the bottom."

Miyashiro, retired from University of Albany as geology professor, came to the park Tuesday evening to take pictures with his wife, Fumiko. He went off by himself around 7:30 p.m. and never returned. Authorities from a number of agencies searched for him for 36 hours until the body was discovered 11:30 a.m. Thursday by rescuers who had rappelled the rock cliff.

The body could not be brought up the cliff because of hard rain Thursday morning that made rocks slippery.

"It was absolutely treacherous and dangerous," Defrancesco said. Instead, a rescue crew hiked more than 300 yards into the woods from the bottom of the cliff and carried the body out.

Miyashiro retired from UAlbany's Department of Geological Sciences in 1991 after a 22-year career there that earned him international acclaim. Geology has nothing comparable to a Nobel Prize, but in 1977 Miyashiro won one of the field's most prestigious honors, the Geological Society of America's Arthur L. Day Medal.

The Japanese scientist worked at UAlbany when its fertile geology unit was known as one of the best small departments in the country.

He arrived via Columbia University in 1969, several years after the theory of plate tectonics hit the stage. The concept holds that the Earth consists of about a dozen major plates that move around, and on their edges occur volcanoes, mountains and earthquakes. It encompasses virtually everything we think about the Earth today.

Miyashiro was a plate tectonics pioneer. He studied the behavior of rocks at very high temperatures and pressures. His field is known as metamorphic petrology. He wrote the classic textbook "Metamorphism and Metamorphic Belts."

"He made major contributions to our current understanding of how major mountain systems formed," said John Delano, a professor of environmental science at UAlbany and a former colleague of Miyashiro's.

He was not a social colleague. People who worked in his department described Miyashiro as a gentleman who maintained high standards. But he was also a private person who economized his words and did not collaborate on research like some of the other professors.

Susan Anderson was his student. The Guilderland teaching assistant remembered how Miyashiro would say that one of his former students had named a mineral after him. "He would get this little giggle and say, 'Unfortunately very rare.' "

Geologists the world over have expressed their condolences

Department of Geology and Geophysics, Yale University GEO-METAMORPHISM@JISCMAIL.AC.UK

"That indeed is very sad news. He certainly helped greatly to advance
the field, and we all owe him a lot.
------------------------------------------------------------

Miyashiro's Geological Petrological Contributions

Miyashiro's paper in J Petrology (Miyashiro A. Evolution of metamorphic belts. J. Petrology 2:277-311, 1961) is a citation classic. He authored it while at the Geological Institute, Faculty of Science, University of Tokyo, Japan. The paper has been
cited over 300 times ever since.

In 1979 he commented on this paper “I began to work on metamorphic rocks of Japan at Tokyo University in 1947 under postwar difficulties. At that time, Alfred Harker’s book, Metamorphism,1 was very influential. It was claimed in this book that the regional metamorphism of the Barrovian sequence in Scotland is standard or ‘normal’ on a worldwide scale, and that minerals characteristic of such ‘normal regional metamorphism’ are stable only in the presence of strong shearing stress. However, such ‘normal regional metamorphism’ did not exist in Japan. Thus, my main problem was to clarify how and why the regional metamorphism of Japan differs from Harker’s ‘normal regional metamorphism.’ I expected that I would be able to show the existence of a number of different types of regional metamorphism. I discussed it, for example, in relation to the compositional variation of metamorphic garnet in 1953.2 Moreover, I doubted Harker’s view emphasizing the necessity of shearing stress in the formation of certain metamorphic minerals. This motivated my proposal in 1949 of a hypothetical phase diagram of the Al2SiO5 minerals to explain their formation in terms of temperature and hydrostatic pressure only.

“In the 1950s, a new improved system of graduate school was begun in Japan. I had many brilliant students (undergraduate and graduate) in metamorphic petrology such as F. Shido and S. Banno at Tokyo University in addition to my friend Dr. Y. Seki who was already a fullfledged metamorphic petrologist. Spontaneously we formed an active cooperative group. Banno and Seki studied few glaucophaneschist terranes, and discovered that glaucophane forms only in a limited range of temperatures in progressive metamorphic sequences. This gave strong support to the existence of the glaucophaneschist facies. “After several years of our cooperative study, I came to feel that we had already understood the main features of the two major types of regional metamorphism existing in Japan, and that these two types, together with one more type corresponding to Harker’s ‘normal regional metamorphism,’ represent the three basic categories of regional metamorphism existing on Earth. I wrote this view in my 1961 paper. At that time, petrology had little connection to tectonics. The concept of paired metamorphic belts, described in this paper, was one of the earliest attempts to connect metamorphic petrology to tectonics.

“It is gratifying to know that the paper has been so frequently cited. It is a memorial to
our metamorphic petrology group of the 1950s and the early 1960s in Tokyo.”
[http://www.garfield.library.upenn.edu/classics1979/A1979HE73300001.pdf]


Facies


Miyashiro (1973) renamed Turner (1968)'s prehnite-pumpellyite metagraywacke facies

as the prehnite-pumpellyite facies

Miyashiro (1961) developed the concept of the metamorphic facies series. This is a sequence of metamorphic facies developed under a particular range of P/T. For regional metamorphism Miyashiro (1961) suggested three principal facies series and the

existence of some intermediate facies series. Later (Miyashiro, 1973a), he referred to them as

baric types of metamorphism because they broadly indicate different radial sectors in a P-T

diagram such as Figure 2.3 (e.g. Miyashiro, 1994, Fig.8.1; Spear, 1993, Fig.2-3) and are

distinguished by their range ofP/T rather than their range ofpressures or temperatures. The three

principal baric types are: 1. low-P/T type (also referred to as the andalusite-sillimanite series or Abukuma type)

characterised by andalusite at lower grades and sillimanite at higher grades and typified by the

sequence greenschist f.→amphibolite f.→granulite f.;


2. medium-P/T type (also referred to as the kyanite-sillimanite series or Barrovian type)

characterised by kyanite at lower grades and sillimanite at higher grade and typified by the

sequence greenschist f.→epidote-amphibolite f.→amphibolite f.→granulite f.;

3.

high-P/T type (also referred to as glaucophanic metamorphism) characterised by the

presence of glaucophane and typified by the sequence subgreenschist f. (prehnite-

pumpellyite)→glaucophane-schist/blueschist f.

The three principal metamorphic facies series of Miyashiro have been generally adopted (e.g.

Yardley, 1989; Spear 1993; Kornprobst, 2002) although, it is accepted that subdivisions,

intermediates and variants exist (e.g. Harte & Hudson, 1979; Miyashiro, 1994)