| Citation | Distinguished for his fundamental researches into the role of volatile components in the genesis of igneous and metamorphic rocks. He has been strikingly successful in devising and conducting programmes in experimental synthesis, at high temperatures and pressures, that have added substantially to knowledge on the evolution of the Earth's upper mantle and crust. His important discovery, in 1959, that calcite could be precipitated from melts at moderate temperatures, solved a 50 year-old problem regarding carbonatite magmas and led him to a long series of studies involving silicate-water-carbon dioxide systems. These were applied particularly to the genesis of alkalic igneous rocks, the role of H2O-CO2 vapours in metamorphic reactions, and the problems of kimberlite origins and amphibole breakdown in the upper mantle. Subsequent studies of the system basalt-andesite-rhyolite-water, from 1 bar to 35 kilobars pressure, have important bearing on volcanism in subduction zones and crustal anatexis. Throughout, he has combined elegant experimental work with an acute perception of contemporary problems in the Earth Sciences. |