- Thomas Edvard Krogh
Thomas Edvard "Tom" Krogh, FRSC (1936 –
April 29 ,2008 ) was a geochronologist and a formercurator for theRoyal Ontario Museum . He revolutionized the technique of radiometricuranium-lead dating with the development of new laboratory procedures and analytical methodologies. His discoveries have yielded an unprecedented level of precision in the dating ofPrecambrian rocks. Krogh’s techniques have become the international defacto standard. The application of these techniques has provided a detailed understanding of the evolution of the Earth's Precambrian shield areas.Education
Krogh was born in
Peterborough, Ontario . Between 1955 and 1959, he studied geological engineering atQueen's University and held several jobs. For the first two summers he worked as a Geological Assistant at Noranda Mines andTriana Explorations , respectively. Between 1957 and 1959, he worked as a Teaching Assistant at the university. In 1958, he supported theGeological Survey of Canada as a Geological Assistant. In 1959, he was a Senior Assistant for the Ontario Department of Mines. Krogh obtained a MSc in geology from the university in 1960. He left Canada to study at theMassachusetts Institute of Technology , where he continued to work whenever he was not studying. His first job was as a Teaching Assistant in Mineralogy, then as a Geologist at Cominco, then as a Research Assistant inGeochronology . In 1964, he obtained his PhD in geochronology.Career
Between 1964 and 1975, Krogh worked at the Carnegie Institution in
Washington, D.C. He was a post-doctoral fellow inisotopic geochemistry until 1964 when he became a Scientific Staff Member. From 1964 to 1970, he specialized inRubidium –Strontium dating of minerals and rocks. In 1970, he switched to specializing in the Uranium-Lead dating ofzircon s and other minerals.In 1975, Krogh returned to Canada to work as the Associate Curator/Director of the Royal Ontario Museum’s Geochronology Laboratory. In 1976, he became a Professor in the Geology Department of the
University of Toronto . In 1978, he shifted to be Graduate Faculty Member with the university.In 1979, he returned to the Royal Ontario Museum to be their Full Curator.
He worked on the
Lithoprobe project between 1991 and 1996.Discovery
Krogh’s main focus of research has been geochronology, an effort which has long involved the integration of field work (particularly in high-grade gneisses of the Grenville Province) with clean-laboratory isotope dilution techniques. With uranium-lead (U-Pb) dating he developed a simple, yet innovative air-abrasion technique for removing exterior portions of minerals that may have suffered Pb-loss, which, combined with improved magnetic separation methods, greatly improved the accuracy and precision of zircon geochronology. In addition, Krogh's laboratory methods for the dissolution of minerals and the subsequent chemical separation of trace quantities of uranium and lead resulted in a significant reduction of environmental Pb contamination (blank) to ultra-low levels, and permitted increasingly small quantities of mineral grains and sub-grain domains to be analyzed. In the mid-1980's, he was instrumental in producing a synthetic 205Pb isotopic tracer (spike) that was distributed for use in U-Pb geochronology laboratories worldwide. The application of Krogh's novel and innovative techniques has revolutionized U-Pb geochronology and permitted the ages of rocks to be determined with unprecedented accuracy and precision. Most of what is known of the Earth’s 4.5 billion-year history has been placed in precise geological sequence using these dating methods.
Honors
*1989, awarded the
Logan Medal by theGeological Association of Canada
*1990, made a fellow of theAmerican Geophysical Union
*1991, bestowed an honorary D.Sc. by Queen’s University
*1991, awarded theJ. Tuzo Wilson Medal by theCanadian Geophysical Union
*1994, became an elected member of theNorwegian Academy of Science and Letters
*1995, became a distinguished fellow of the Geological Association of Canada
*1996, awarded the Past President’s Medal by theMineralogical Association of Canada
*1997, became a Geochemistry Fellow of theGeochemical Society andEuropean Association for Geochemistry
*1999, became an elected fellow of theRoyal Society of Canada elect publications
*Davis, D.W., Williams, I.S., Krogh, T.E., 2003. "Historical development of zircon geochronology". In Reviews in Mineralogy and Geochemistry, J.M. Hanchar and P.W.O. Hoskin (Editors) volume 53, p.145-181.
*Krogh, T.E., Kamo, S.L., Gower, C. and Owen, J.V., 2002. "Augmented and reassessed U-Pb geochronological data from the Labradorian-Grenvillian front in the Smokey archipelago, eastern Labrador". Canadian Journal of Earth Sciences 39: 831-843.
*Krogh, T.E., Kamo, S.L. and Bohor, B. 1996. "Shock metamorphosed zircons with correlated U-Pb discordance and melt rocks with concordant protolith ages indicate an impact origin for the Sudbury Structure". In Earth Processes: reading the isotopic code. A. Basu and S. Hart, eds. Geophysical Monograph 95, Washington, D.C.: American Geophysical Union, pp. 343-353.
*Chen, Y. D., Krogh, T. E., Vetrin, V. R. and Mitrofanov, F. P. 1994. "Precise zircon geochronology on Archean rocks sampled by the world's deepest continental borehole, SD-3 Superdeep Well, Kola Peninsula, Russia". ICOG-8 Program with Abstracts, 56..
*Krogh, T.E., Kamo, S.L., Sharpton, V., Marin, L. and Hildebrand, A.R. 1993. "U-Pb ages of single shocked zircons linking distal K/T ejecta to the Chicxulub crater". Nature 366: 731-734.
*Krogh, T.E. 1988. "High precision U-Pb ages of single zircons and parts of zircon in simple and complex populations". Chemical Geology 70: 70.
*Krogh, T.E. 1961. "The titaniferous magnetite deposit of the Newboro District". M.Sc. Thesis, Department of Geology, Queen's University, Kingston, Ontario.
*An entry in "Encyclopædia Britannica " on isotopic dating.References
* [http://www.zoominfo.com/Search/PersonDetail.aspx?PersonID=28625115 ZoomInfo Bio]
* [http://www.rom.on.ca/news/releases/public.php?mediakey=xhwvrc4j3d ROM Curator inducted into Royal Society of Canada]
* [http://www.britannica.com/eb/author?id=3722 Encyclopædia Britannica]
* [http://www.queensu.ca/secretariat/HDrecipients.pdf Queen’s University- Honorary degrees]
* [http://vgp.agu.org/fellow_award.html American Geophysical Union- Fellows]
* [http://www.mineralogicalassociation.ca/index.php?p=53 Mineralogical Association of Canada- Past President’s Medal]
* [http://rock.geosociety.org/sgt/SGTNewsMar93.html Geological Society of America Newsletter- March 1993]
* [http://www.geology.utoronto.ca/Alumni/alumni_news.pdf University of Toronto Geology Division Alumni Newsletter]
* [http://hcr3.isiknowledge.com/author.cgi?&link1=Browse&link2=Results&id=1781 ISI Knowledge Krogh Bio]
* [http://communications.uvic.ca/releases/tip.php?date=17111999 University of Victoria- Duo Honoured by Royal Society]
* [http://WWW.LAPIDARYJOURNAL.COM/ARCHIVE/MAY00NEWS.HTM Lapidary Journal- May 2003]
* [http://cache.zoominfo.com/cachedpage/?archive_id=0&page_id=406003958&page_url=%2f%2fwww.rsc.ca%2fenglish%2fnew_fellows_1999_EOAS.html&page_last_updated=7%2f10%2f2004+5%3a20%3a27+AM&firstName=Thomas&lastName=Krogh Royal Society of Canada- 1999 Fellows]
* [http://www.dtm.ciw.edu/content/view/488/2/ Notice of death] Retrieved onMay 9 ,2008 External links
* [http://www.astrobio.net/cgi-bin/h2p.cgi?sid=293&ext=.pdf When did the Earth Begin? Ask a Rock]
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