Citation for Dante Canil
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 DV 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
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
Citation for Tim Elliott
Timothy (Tim) Richard Elliott is an isotope geochemist in the broadest sense of the term. After a PhD at Open University with Chris Hawkesworth as adviser, he went to Lamont as a post-doc and then to Amsterdam. He became a faculty at the University of Bristol in 1999. Dressing and chucking like a teenager but thinking and performing as a Jedi of Geochemistry, he combines, as his long-term friend Terry Plank puts it, “a child-like curiosity and generous mentorship with an utterly honest and brutal view of shabby work”.
Like a journeyman in previous centuries, Tim has gone through many of the basic techniques, learning to master neodymium, thorium-uranium, lead, nickel, magnesium, and tungsten isotopes with utmost proficiency before he tackled the most daunting challenges left unsolved by the pioneers of mantle and planetary geochemistry. He left his mark on a number of problems that have since become common knowledge, like the U-Th series in the Mariana volcanics as a marker of melting processes, the subduction factory, the history of the uranium cycle, and evidence of tungsten isotope heterogeneities attesting to live 182Hf in the early Earth. Tim is an unusual crossbred with outstanding analytical talent, rigor, and a deep understanding of the theoretical aspects of geochemistry. With Milton Keynes, Lamont, and Bristol efficiently nurturing Tim’s developing personality, his nature, that of a mind both independent and creative, rapidly revealed itself and has long since come into its own.
Time has now come to recognize Tim as one of the leading geochemists in his generation. Dear President and dear Colleagues, I am particularly proud to present to you the 2016 recipient of the Norman Bowen Award of the Volcanology, Geochemistry, and Petrology Section of the American Geophysical Union, Timothy Richard Elliott.
—Francis Albarède, Ecole Normale Superieure Lyon, France
It is daunting to respond in black and white to Francis’ blushingly generous words. He has known me long enough to see more than just the questionable garb, so I am very grateful for his focus on the positive and longstanding support. Briefly wandering back down the memory lane Francis sketched, I think we are both misty-eyed about the excitement of research and life on the banks of the Hudson. To me this was certainly a fillip after the concrete cows of Milton Keynes, although this well-ordered suburban environment did inspire a comeraderie amongst the plucky few who chose to ask questions of Earth rather than estate agents. I remember the weekly window on a largely mysterious world provided by Eos, then in print form. This world, and indeed the bits I had never understood in Scooby Doo, were made gloriously manifest to me during my time at Lamont. Subsequently swapping Old for New Amsterdam seemed a fair exchange; I fear my lack of ostensible productivity during that era would be fatal now, but the freedom I was afforded for intellectual and technical rumination was enormously valuable. Thence my personal Brexit, which has proven to be the stuff of the impossible dreams of the Vote Leave campaigners.
I am hugely buoyed by the kind efforts of those who nominated me. Multitudinous thanks go out to the many who have helped me along a somewhat circuitous path and kept surprising faith in what I have been sometimes doing. I won’t name names, as the list would inevitably be both remiss and too long. Having spent much of my career assuming that the function of Awards Presentations was as a time out for much needed recuperation, I also appreciate the bravery of the committee for giving me a chance to engage.
—Tim Elliott, University of Bristol, United Kingdom