Richard Lee Armstrong

Richard Lee Armstrong (born August 4, 1937 in Seattle , Washington , † August 9, 1991 in Vancouver , British Columbia ) was a Canadian geologist and geochemist and professor at the University of British Columbia .

Life

Armstrong studied at Yale University with a bachelor's degree in 1959 and a doctorate in geology in 1964. As a post-doctoral student he was at the University of Bern and then an assistant professor and later an associate professor at Yale. In 1968/69 he was a Guggenheim Fellow at the Australian National University and at Caltech . In 1973 he became an Associate Professor and later Professor at the University of British Columbia (UBC).

He mainly dealt with age dating of igneous rocks with radioactive isotopes in the Cordilleras in western North America in order to reconstruct their development history and in general the development history of the earth's crust. To do this, he collected large amounts of isotope data in the Cordilleras and built an extensive database. Already in the early years of plate tectonics (1968) he was convinced that the crustal material of the earth is subject to a constant cycle process and recycling with an essentially constant volume of the crustal material since the Archean, and tried this against contradiction from the ranks of his colleagues in geochemistry to back up long years with data.

In 1966 he introduced the term Metamorphic Veil (metamorphic veil) to describe the fact that the potassium-argon dating is influenced by metamorphosis and shows the cooling time instead of the time the rocks were formed.

Since his dissertation, he has been investigating tectonic processes in the Great Basin in Nevada and Utah and later (1972) discovered when mapping the faults that these faults are often of tertiary origin (consequences of an expansion of the earth's crust and twisted) instead of, as previously assumed, faults of older origin. The work was influential in exploring the geology of the Great Basin.

Armstrong was originally an American and became a Canadian citizen in 1979. In 1981 he became a Fellow of the Royal Society of Canada and in 1990 he received the Logan Medal . In 1986 he received the UBC's Killam Prize . He was involved in Canada's Lithoprobe program to study the structure of the lithosphere . The Armstrong Platform , a plateau in the Antarctic , is named after him .

Fonts

• K-Ar dating of plutonic and volcanic rocks in orogenic belts: Age determination by potassium argon, in: OA Schaeffer, J. Zahringer (Ed.), Potassium-Argon Dating, Springer Verlag 1966, pp. 117-133.
• A model for Pb and Sr isotope evolution in a dynamic earth, Reviews of Geophysics, Volume 6, 1968, pp. 175-199.
• Low-angle faults, hinterland of the Sevier orogenic belt, eastern Nevada and western Utah, Geological Society of America Bulletin, Volume 83, 1972, pp. 1729-1754.
• Radiogenic isotopes; The case for crustal recycling on a near-steady-state no-continental-growth Earth, Philosophical Transactions Royal Society of London, Volume 301, 1981, pp. 443-472.
• Mesozoic and Early Cenozoic Magmatism of the Canadian Cordillera, GSA Special Papers, Volume 218, 1988, pp. 55-92
• with R. Parrish: A geologic excursion across the Canadian Cordillera near 49 ° N (Highways 1 and 3 from Vancouver to southwestern Alberta and on to Calgary, Alberta), Geological Association of Canada Meeting, Vancouver, May, Field Trip Guidebook, 1990 ( 71 pages)
• with WB Harland, AV Cox, LE Craig, AG Smith, DG Smith: A Geologic Time Scale, Cambridge University Press: Cambridge, 1989
• The Persistent Myth of Crustal Growth. Austral. J. Earth Sci., Vol. 38, 1991, pp. 613-663

Web links

• Obituary by Randall Parrish, GSA, Structural Geology and Tectonics Division Newsletter 1993