Marion Garçon and Daniel A. Stolper received the 2019 Hisashi Kuno Award at AGU’s Fall Meeting 2019, held 9–13 December in San Francisco, Calif. This early-career award recognizes “outstanding contributions to the fields of volcanology, geochemistry, and petrology.”  

Marion Garçon, starting with her Ph.D. thesis, has made seminal and definitive contributions to geochemistry. Her thesis was a milestone in our understanding of the so-called “zircon effect” in sediments. This effect causes the Lu/Hf ratios of pelagic clays to be systematically higher than the corresponding ratio in the continental sediment sources. Hafnium in sediments is sequestered in zircons, and most of those zircons don’t make it into the deep sea. Marion showed where and how this zircon sorting starts in rivers long before the sediments are carried out to sea. This led to greatly improved understanding of how mineral sorting fractionates the chemical and isotopic compositions of sedimentary material.

Marion followed this with a definitive study of the role of accessory minerals in dominating the isotopic composition of sediments, not only for zircons but also for allanite and monazite, as well as K-feldspar. Next, she showed how erosion and transport biases the composition of sediments: In a large-river water column, the near-surface suspended sediments overrepresent the mafic portion of the source region, while the near-bottom sediments are biased toward the more felsic source materials.

In a recent paper, Marion delineated the major source components of classic early Archean Barberton sediments from South Africa. She showed that the detrital sedimentary component derived from a crust that is 300–400 Ma older is dominated by mafic–ultramafic sources. Overall, she showed that the South African Archean crust has about 60% SiO2 and is thus significantly more mafic than more recent continental crust.

Most recently, she has contributed an exhaustive investigation of the mass spectrometric methodology needed to achieve the “ultimate” precision for Nd isotope ratio measurements, one which is limited only by counting errors.

I stand in awe of the originality, thoroughness, and exceptional quality of Marion’s work.

—Albrecht W. Hofmann, Max Planck Institute for Chemistry, Mainz, Germany

Thank you, Al, for your support. It is an honor to receive this unexpected award, and I would like to thank all the people involved in my nomination, the Kuno committee, and the Volcanology, Geochemistry, and Petrology (VGP) section for awarding me this prize. I owe a lot to my Ph.D. adviser, Catherine Chauvel, who introduced me to geochemistry during my master’s. She was a wonderful Ph.D. adviser who passed on to me her passion and rigor of analytical chemistry. Thank you, Catherine, for being so enthusiastic and supportive from the beginning. I would not be here today without you. Following my Ph.D., I was lucky enough to do a postdoc at Carnegie Institution with Rick Carlson and Steve Shirey, who are incredibly talented researchers, always keen to discuss ideas, results, and analytical issues. I learned a lot from you and thank you for making my Carnegie experience wonderful from both the professional and personal points of view. I am also grateful to Maud Boyet, who welcomed me with open arms at Clermont-Ferrand and was always very supportive when it came to writing applications, grants, and manuscripts. She is a bright person with a lot of human qualities, and I am very happy to have her as a colleague now. Finally, I thank my colleagues, office mates, and collaborators at Terre, Carnegie, ETH Zürich, and Laboratoire Magmas et Volcans for making my daily working life rich and fun. Of course, none of this would have been possible without the unconditional support of my wife, Lucie, who coached me on so many talks and interviews. I also thank my parents and parents-in-law, who were always supportive of my professional choices even if they still do not really understand what I do with rocks. I feel very lucky to have you all and our baby girl, Jade. —Marion Garçon, CNRS Laboratoire Magmas et Volcans, Clermont-Ferrand, France