Canil Receives 2016 N. L. Bowen Award

Dante Canil will receive the 2016 N. L. Bowen Award at the 2016 American Geophysical Union Fall Meeting, to be held 12–16 December in San Francisco, Calif. The award recognizes “outstanding contributions to volcanology, geochemistry, or petrology.”

Citation

The Bowen Award is presented to Dante Canil in recognition of his seminal work on the history of the oxygen fugacity of the upper mantle.

By the early 1990’s Fe³⁺/Fe²⁺ measurements of peridotites and MORB glasses indicated that the modern suboceanic mantle melts under oxygen fugacity conditions somewhat below the NNO buffer. But we knew little about the history of mantle oxidation state. Dante addressed this question by determining the partitioning of vanadium between olivine and silicate melt. He showed that the olivine-liquid partition coefficient D_V decreases by more than an order of magnitude as the oxidation state of V increases from +2 to +4 with increasing oxygen fugacity. Thus, he demonstrated that Archaean komatiites (up to 3.5 Ga) crystallised olivine under fO₂ conditions slightly below NNO and hence under similar conditions to modern oceanic basalts. His conclusion was “If the fO2 values recorded by basic magmas represent the fO2 of their mantle source region then the Archaean mantle source for komatiites is not likely to have been significantly less oxidizing than at present.” The important next step was to determine whether or not the Archaean mantle residue showed the same oxidation state as the lavas. Dante measured V partitioning into spinel, orthopyroxene, clinopyroxene and garnet. This enabled him to track V/Al ratios of peridotite residues from partial melting at different oxygen fugacities. He showed in this way that garnet peridotites from Archaean cratons exhibit melting depletions at oxygen fugacities about 1 log unit below the NNO buffer ie under similar conditions to those recorded by Archaean komatiites and modern oceanic basalts. Dante Canil’s groundbreaking work thus demonstrates that the oxygen fugacity of the upper mantle played no role in the rise of atmospheric oxygen and has remained approximately constant at the current value for at least 3.5 Ga.

—Bernard Wood, Oxford University, United Kingdom

Response

I thank Bernie Wood for this nomination, the Awards committee and all at AGU for their selfless efforts in adjudicating awards like these. How humbling such awards are. In a career one encounters so many other people to measure up to that it then becomes almost embarrassing to receive an award for what one loves to do. On this note I thank all those people I cannot name whose work I have read, learned from and aspired to match. Every neat idea I have had spawned from some isolated sentence in your paper. In my mind I share this award with you. I also thank those people who in some way took a chance on me along the way: Chris Scarfe, Dave Virgo, Fritz Seifert, Don Dingwell and Hugh O’Neill. I also thank my wife Terri and daughter Olivia for personal balance in a life occupied with science. I thank my parents for teaching me to balance modesty with pride, and to maintain a strong work ethic. I am a particularly honoured for this award because like Bowen, I am a Canadian, started geology in the bush and found myself in experimental petrology. Bowen saw how field observations could be later grounded in experiment. Nature is surely complex, and there are of course many more experiments to do, but they are not always sophisticated or expensive. Many of them require only imagination and paying attention to the work of others. For this reason, if you are a younger person in the audience I would urge you to not tow a party line, always look where your research speaks to other fields, and realize that you do not always need huge resources to make scientific progress. This has been my motto and I thank you all again for this incredible honour.

—Dante Canil, University of Victoria, Canada