Graham Pearson merits the 2019 Norman L. Bowen Award for adding to our fundamental understanding of igneous processes in the upper mantle through studies of volcanic rocks, exhumed mantle sections, subcontinental mantle samples, and diamonds and their inclusions. Pearson has tackled the major topics in mantle geochemical evolution with a research tool kit that ranges from petrography, mineralogy, and petrology through stable isotopes, radiogenic isotopes, siderophile elements, and spectroscopy. In using these techniques, Pearson has sought new analytical method developments that push the frontiers of analytical sensitivity and precision.
Colleagues will remember a long list of discoveries: large pieces of Earth’s mantle emplaced from the diamond stability field; eclogite xenoliths in kimberlite as Archean subducted oceanic crust; continental mantle keel age-match with overlying crust; Re-Os sulfide age-dating of single sulfide inclusions in diamond; kimberlite derivation from unique mantle sources; the Os isotopic imprint in the oceanic mantle of continental crust extraction; trace element abundances in gem diamonds and source fingerprinting; a modern subduction analogue for Archean craton formation; and the finding, in a superdeep diamond, of the first terrestrial ringwoodite.
In this latter accomplishment, we see a typical example of why Graham Pearson is especially deserving of the Bowen Award. He led the effort to successfully measure the water content of a delicately metastable single grain of ringwoodite while it was encased in the diamond so it could avoid breakdown and thereby retain all of its original water. In perhaps one of the most important mineral analyses ever made, Pearson and coworkers were able to show directly that the ringwoodite had approximately 1.5 wt % water. For the first time, here was confirmation that the mantle transition zone can be wet.
In consideration of the sum and variety of his contributions, we deservedly honor Graham Pearson for the wide interdisciplinary influence of his work in understanding the mantle at all depths.
—Steven B. Shirey, Carnegie Institution for Science, Washington, D.C.
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Heat generation within the cratonic lithospheric mantle (CLM) is an important but poorly determined parameter for constructing cratonic geotherms. ...
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