Allegre, Claude (earth scientist)

(1937- ) FrenchGeochemist

After establishing an outstanding career in the Earth sciences, Claude Allegre became one of the few scientists to participate successfully in governmental policy. Claude Allegre is the architect of the subdiscipline of isotope geodynamics. This area involves the study of the coupled evolution of the mantle and continental crust of Earth through a multi-isotopic tracer approach. These radiogenic isotopes include such systems as strontium, neodymium (and samarium), lead, xenon, argon, helium, osmium (and rhenium), and thorium. The studies provide evidence for very early degassing of volatile elements and compounds from Earth with limited subsequent mixing between the upper mantle and the lower mantle. They also show that the atmosphere was primarily formed early in the history of the Earth with only volumetrically small additions since. Helium and neon were trapped in the Earth’s interior and have been escaping at a slow rate ever since. He geochemically modeled the early solar system, the early evolution of planets and the formation of meteorites in his paper, “Cosmochemistry and the Primitive Evolution of Planets,” among others. This cosmochemical research is the reason that Allegre was chosen by NASA to participate in the Apollo lunar program. In that role, he was among the first scientists to determine the age of the Moon.

With regard to the visible part of the Earth, his paper “Growth of the Continents through Time,” in which he uses isotopic evidence to address the topic, exemplifies Claude Allegre’s research. Once isotopes are removed from the open whole-Earth system into a closed continental system, they evolve separately. Allegre’s best-known research is on the Himalayan mountains, both in terms of structural and geochemical evolution of the Asian crust. However, in considering the iso-topic systematics produced by erosion of the continental crust, he also looked at Africa and South America. The other main area of research that Al-legre has undertaken is to apply his considerable physics and mathematical background to scaling laws of fractures, earthquakes, geochemical distributions and energy balance which mathematically relates sizes to distributions.

Claude Allegre is probably best known by the public for his extensive governmental work. He is currently the minister for National Education, Research and Technology for France, where he has created quite a controversy by attempting to overhaul the public educational system. Certainly, it takes plenty of prior policy work to be appointed to such an important position. Allegre served as a member of the Socialist Party Executive Bureau, a National Delegate for Research, and a special adviser to the first secretary of the Socialist Party. He was a member of the European Parliament, a city councilman of Lodeve, and a member of the Languedoc Roussillion Regional Council.

Claude Allegre was born on March 5, 1937, in Paris, France. He attended the University of Paris, where he studied physics under Yves Rocard as well as geology, earning a Ph.D. in physics in 1962. He was an assistant lecturer in physics at the University of Paris from 1962 to 1968 before accepting a position as assistant physicist with the Paris Institut de Physique du Globe. He has been the director of the geochemistry and cosmochem-istry program at CNRS (French National Scientific Research Center) since 1967. Allegre joined the faculty at the University of Paris VII in 1970, a position he retains. In 1971, he was appointed as director of the Department of Earth Sciences, a position he held until 1976. He was then named the director of the Paris Institut de Physique du Globe from 1976 to 1986. In 1993, he was named as a member of the Institut Universitaire de France (Denis Diderot University). Allegre was recently granted a leave from his academic position to serve as minister for National Education, Research and Technology for France. Over the years, Allegre has held several visiting scientist positions on an international basis. He was a White professor at Cornell University, New York, a Crosby Professor at Massachusetts Institute of Technology, and a Fairchild Professor at the California Institute of Technology, in addition to positions at the U.S. Geological Survey, Denver; the Carnegie Institution of Washington, D.C.; University of California at Berkeley; and at Oxford University, England. Claude Allegre is married with four children.

Claude Allegre is an author of more than 100 scientific articles in both English and French. Many of these papers are seminal studies on the evolution of the Earth, especially using isotopic evidence. They appear in respected international journals. Even to popular books. In recognition of his scientific contributions, Allegre has received numerous honors and awards. He is a member of the U.S. National Academy of Sciences, the American Academy of Arts and Sciences, and the French Academy of Science, as well as an officer of the Legion of Honor. He received the Crafoord Prize from the Swedish Royal Academy of Science, the Goldschmidt Medal from the Geochemical Society (U.S.), the Wollas-ton Medal from the Geological Society of London, the Arthur L. Day Medal from the Geological Society of America, the Gold Medal from CNRS (French National Scientific Research Center), the Arthur Holmes Medal from the European Union of Geoscience, and the Bowie Medal of the American Geophysical Union.

Next post:

Previous post: