Alain Weisbrod (1936-2005)

Alain Weisbrod left us on October, 18th 2005 after a very long disease.

Alain entered the Geology School in 1956. Valedictorian, he was appointed Assistant when he left school, and started a PhD on median Cevennes crystal, which he defended in 1970, untitled: Petrology of median Cevennes basement metamorphic rocks. Sedimentological reconstruction and thermodynamic perspective of metamorphism.All along his career, he was a teacher-researcher at the Geology School, as an Assistant (1959), Teaching Assistant (1965), University Lecturer (1970), and then Professor (1976) until he retired in 1998.

In this school, he taught crystal chemistry and mineralogy, metamorphism petrology, some lessons on metallogeny, physical-chemistry and conventional thermodynamics applied to Earth Sciences. He also led the second year internships, studying crystalline soil in Ardèche from 1962 to 1995 that is to say for more than thirty years. He was very close to the pupils of the school. Moreover, he was responsible for the entrance examination of Geology School from 1981 to 1994. Alain was strongly attached to this School and to his students. With Jacques Fabries and Jacques Touret, he promoted a new vision of petrology and greatly contributed to the introduction of hard sciences in this School teaching.

After his PhD, he was a researcher in the Geochemical and Petrographic Research Center (CRPG-CNRS) in Vandoeuvre lès Nancy. Firstly, during ten years in the Research Team on the Balance between Minerals and Fluids, which he founded with Jacques Touret and I in 1969, and then, from 1979, in his own team. In these teams, he worked on petrology, on the study of fluid inclusions, on experiments at high temperature and high pressure, and on the metallogeny of acid starting deposits: tin and tungsten, and porphyry copper in particular. He also trained many researchers. Finally, he was welcomed by the Geophysical Laboratory of Washington as a Staff Member during 1972-1973 academic year where he worked on the garnet-cordierite balance (influence of water and Mn content).

I still remember our first meeting, in 1969, to define the project of our future collaborative work. All of a sudden, he told me directly: “you did a good job with your fluid inclusions but as long as we haven’t got their chemical composition, we won’t be able to do anything with them, we won’t be able to calculate anything. So they are of no use!” (“Tes inclusions fluides c’est bien, mais tant qu’on n’aura pas leur composition chimique on ne pourra rien en faire, rien calculer. Elles ne servent donc à rien !”).Actually, I knew he was right, but in 1969, I did not know how we could undertake a fluid chemical analysis inside cavities of a few dozen cubic microns… But it started to bear fruit: two years later, in the CRPG, we created a laboratory helping us to approach the problem.

At first, his publications were of a pedagogical nature: new edition of “Little Roubault. Determination of minerals with a polarizing microscope”, collaborative work with Jacques Fabriès and Jacques Touret, under the direction of Marcel Roubault (1963); the book “Basic Thermodynamic for Mineralogists, petrographers and geologists”, written with Raymond Kern, published in 1964, translated into Russian (1966) and English (1967), helped him gain international attention. Well ahead of its time, this book inspired British literature years later. Actually, it corresponds to the first application of thermodynamics in the study of mineralogical balances, at the basis of all modern study of metamorphism.

Thus, Alain behaved as a particularly well balanced researcher, it was rather unusual at that time. He confronted :

– The terrain: petrographic and structural analysis, analytical data acquisition

– The use of experimental data that he discovered when they didn’t exist

– The modelling of proposed mechanisms.

In the mid-1970s, he turned all his attention to the study of the role of crustal fluids in metamorphic, hydrothermal and post-magmatic phenomena. In the crustal fluid field, Alain was interested in the H2O-salt system topology, in immiscibility phenomena and in fluid mixture as a cause of metal deposits, in Alpine metamorphism, in hydrothermal oceanic metamorphism, in metasomatic phenomena at low pressure metamorphism, in equilibrium constant in ultrabasic rock minerals, in K/Nageothermometer calibration of fluids in balance with alkali feldspars, in the balance between cordierite and tourmaline in B content in natural hydrothermal fluids, etc. Most of these publications were done with collaborators, colleagues or students.

He was elected member of the CNRS from 1976 to 1981, and of the National Universities council (deep geology section), that he chaired during a mandate. He was a member of numerous national scientific research committees (in particular in metallogeny) and international (Mineral Thermodynamics). He had a keen interest in the SFMC.

Alain travelled a lot, for his research on the terrain (Europe, Morocco, Indonesia), but also to take part in seminars and symposiums or to deliver conferences (USA, Russia, Europe). He taught in several summer and winter Schools and in three NATO symposiums, “Volatiles in metamorphism” in 1974 (France-Switzerland-Italy), “Thermodynamics in Earth Sciences” in 1976 (Oxford) and « Geochemistry of Hydrothermal Ore-forming Processes » in 1987 (Spain). He was one of the founding members of the biannual symposium “Experimental Mineralogy, Petrology and Geochemistry”, for which he organised the first meeting at Nancy in 1986. 

Alain was married with three children. Close to nature, he had practised climbing all his life long, in France and in Corsica. He was passionate about music and liked to play the piano.

His disease was diagnosed only in 1997, but he was probably ill before 1990. It was an ordeal for him and his family to whom we express our deepest sympathy.

A brilliant figure of Petrology and Metallogeny has left us. Thanks to his teaching and his research, but also thanks to his approach to life, Alain has drawn the attention of many students of the Geology School, and of many young researchers.

Bernard Poty