Citation by Huan Cui
Dr. John Valley is the Emeritus Charles R. Van Hise Professor of Geology at the University of Wisconsin-Madison, where he has taught for 39 years. As the director of the Wisconsin Secondary Ion Mass Spectrometer Laboratory (WiscSIMS), John’s work has significantly contributed to improving microanalysis techniques of stable isotope ratios by ion beams. John, together with his students and postdocs, employed in situ analysis of various stable isotopes on numerous sample sets, ranging from modern foraminifera, mollusks, otoliths, and teeth to Earth’s oldest mineral (i.e., zircon) and earliest fossils.
John has an extremely broad research interest. He has been working on rocks (igneous, metamorphic, and sedimentary) of all ages (Hadean to Recent). The topics he has been leading or actively involved with include, but are not limited to, the evolution of the continental crust, the habitability of early Erath, the credibility of Earth’s earliest fossils, the dynamics of the Great Oxidation Event, the origin of deep-time carbon and sulfur cycle anomalies, the cause and effect of geofluids, paleoclimate signatures recorded in cave deposits, migration history and paleodiet derived from microfossils. Fundamental in John’s research is the robust and careful analysis at a high spatial resolution, which has pushed many frontiers of Earth science forward, including geobiology and astrobiology.
As the mentor of numerous students and postdocs, John has been a true role model on how to be a passionate, rigorous, and humble scientist. As an early career scientist myself, I am certainly not qualified to summarize John’s remarkably distinguished career. But I do have first-hand experience working with him. Thanks to the NASA Astrobiology Institute, I was privileged to work with John from 2015 to 2018 as a postdoctoral researcher. John’s meticulous, pertinent, and timely advice on my manuscripts, including critical but respectful debate and comments, has taught me not only about scientific writing but also about how to be a constructive and efficient mentor and collaborator.
Intrigued by the “intellectual beauty of science” (cited in John’s own words), John keeps doing research and mentoring students after his retirement. His remarkable and still highly active career has been and will be the lighthouse to numerous younger scientists, including me, in our own pursuits of science in the future.
Response by John W. Valley
I’m honored to receive the 2022 GSA Distinguished Career Award from the Geobiology and Geomicrobiology Division. As a geochemist, I have been fortunate to work with many talented geobiologists during my career. I gratefully accept this award in recognition of our shared accomplishments. When I started stable isotope research almost 50 years ago with Jim O’Neil, we needed carbonate samples the size of a pencil point for acid dissolution and analysis by gas-source mass spectrometry. These samples were often obtained by grinding even larger samples. Much of the complexity and beauty of biological material is destroyed by such procedures. Although sample sizes have gotten smaller over the years, the dream of precise in situ microanalysis was elusive until the advent of multi-collector, magnetic-sector secondary-ion mass spectrometers (SIMS) about 20 years ago. Now, after many subsequent developments, rapid high-precision analyses can be targeted to spots 1 to 10 m in diameter. Analytical volumes are a million to a billion times smaller. Accuracy can be excellent, but depends critically on use of standards that match samples and should be critically evaluated. Isotope data are routinely correlated to a wide range of imaging and other in situ techniques to reveal previously unknown correlations and detail.
These new analytical capabilities have opened a candy-store of exciting things to study. We have analyzed O, C, and S isotopes to evaluate vital effects vs. diagenesis, examine seasonality and paleoclimatology, determine migration history and paleodiet, test biogenicity, and more. This has improved our understanding of major events such as the Paleocene-Eocene boundary, the Shuram Excursion, and the Great Oxidation Event. Our studies included samples ranging from modern foraminifera, mollusks, otoliths, pearls, speleothems, and teeth to Earth’s oldest microfossils, but this is just the beginning. Many important discoveries remain as in situ stable isotope microanalysis assumes its rightful position in the geobiologist’s toolbox.