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Former DTM and GL Geochronologist, Thomas Krogh, Dies |
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Friday, 02 May 2008 |
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Second from Left: Thomas Krogh. DTM/GL Archives.
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Former DTM postdoctoral fellow and GL staff member Thomas E. Krogh passed away on 29 April. During his time at DTM (1964-66) and GL (1966-75), he worked in isotope geochemistry and geochronology and—along with DTM staff members Thomas Aldrich and George Wetherill and several GL colleagues—concentrated on the refinement of techniques for Rb-Sr dating of minerals and rocks and U-Pb dating of zircons and other minerals. Among his many innovations to the field, Krogh developed a new dissolution method for zircons, he was instrumental in making X-ray fluorescence a standard tool for ascertaining the suitability of samples for Rb-Sr analysis, and he helped in improving the production and purification of the 205Pb spike.
Following his time at DTM and GL, Krogh worked as a curator at the Royal Ontario Museum’s Geochronology Laboratory and as a professor in the Department of Geology at the University of Toronto.
It was while in those positions that Krogh made the seminal contributions for which he is best known. In the U-Pb analysis of zircons, his development of high-magnetic-field-gradient zircon selection and the single-zircon abrasion method led to routinely near-concordant zircons, giving errors as small as 2 million years in rocks older than 2500 million years. Armed with this capability, he and his associates were able to establish quantitatively the stratigraphy of the world's largest Archean terrane, the Superior Province of the Canadian Shield, with profound implications for the geological evolution of continental crust and ore deposits.
Krogh was a fellow of the American Geophysical Union (AGU), the European Association for Geochemistry, and the Royal Society of Canada. He earned his Ph.D. in geochronology from MIT in 1964.
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