2023 Penrose Medal

Presented to Suzanne Mahlburg Kay

Suzanne Mahlburg Kay

Suzanne Mahlburg Kay
Cornell University


Citation by William and Katherine Snee

Dr. Suzanne Mahlburg Kay has made eminent and impactful scientific contributions throughout her career, with breakthrough research on the fundamental tectonic processes responsible for crustal and mantle genesis along convergent margins. A true daughter of the American Midwest, Sue followed her passion for geology to the University of Illinois and earned a PhD in 1975 from Brown University.

Dr. Kay’s early work on the Aleutians led to the development of the high-pressure “adakitic” geochemical signature - now identified in many arc lavas worldwide. A Fulbright in Argentina sparked four decades of collaborative research on the origin of the Central and Southern Andes. Her Andean publications are an encyclopedic library spanning the entire margin, derived from the most comprehensive sample and geochemical database of Andean igneous rocks in existence. From the caldera-forming ignimbrites of the Puna-Altiplano plateau to the intraplate basalts of Patagonia, Sue has unraveled the petrogenesis of nearly every magmatic center since the Permian. Her multiple applications of trace element ratios and isotopic signatures in “space and time” are masterpieces of deductive reasoning, first applied to the Pampean “flat slab” region, proving that magmas erupted far into the backarc resulted from near-horizontal subduction.

Dr. Kay was among the first to identify magmas associated with the process of crustal delamination. Major advances in her landmark paper (Kay and Kay, 1993) include discussion of the mechanics, timing, and driving forces of delamination – deduced via the geochemical variability of magmas within the Andean delamination zone. She was a pioneer in recognizing the role of subduction erosion in the genesis of magmas associated with arc migration and highlighted its role in crustal recycling. These tectono-magmatic processes are now recognized in convergent margins globally.

Sue has mentored and inspired multitudes of international students and academic collaborators, including Johan Varekamp and Adam Goss, who jointly nominated her for this award. She has advanced the geology of convergent margins as editor of special volumes, organizer of the GSA “Backbone of the Americas” conference, and as GSA President.

Dr. Kay is truly deserving of the Penrose Medal, as she is among the greatest living geologists in the world.


Response by Suzanne Mahlburg Kay

I owe a huge debt of thanks to my co-nominators Dr. Adam Goss and Professor Dr. Johan Varekamp for their overly generous citation for the Penrose Medal, an honor I never expected to receive. I am extremely humbled and overwhelmed to follow my father-in law Marshall Kay who was the 1971 Penrose medalist.

It seems I have been surrounded by Penrose and other medalists who have inspired and encouraged me throughout my career, and it is hard to believe I am joining their ranks. l remember the 1971 Penrose medal presentation to Marshall Kay when I was a graduate student at Brown University. Little did I know I would marry his son, Robert (Bob) W. Kay, whose papers we were reading in a petrology seminar led by Professor Malcolm Rutherford. Further, it was the 1992 Penrose medalist John Dewey who introduced me to Bob. I knew the Kay family was geological, but was still surprised when the first question my future father-in-law asked was what I thought of plate tectonics. Also there was Bob’s brother-in-law, the 1996 Day medalist Robert Berner, who later introduced me to the 1992 Penrose medalist John Rodgers, who asked if I was worthy to join what he called “the first family of geology”. The Kay geology family also includes Pleistocene geologist George F. Kay, paleobotanist Inez Clark Kay, low temperature geochemist Elizabeth Kay Berner, Duke University vertebrate paleontologists Richard Kay and Blythe Williams, John Berner who was at British Petroleum, and geology major University of Colorado atmospheric science professor Jennifer Kay. Holiday dinners were often like scientific meetings.

On leaving Brown after completing a PhD on feldspars with Professor Richard Yund and having the privilege of interacting with Professors William Chappell and Jan and Terry Tullis who were enchanted with plate tectonics, I went as a post doc to UCLA where the 2004 Penrose medalist Gary Ernst encouraged studies of the Aleutian arc. Then on to Cornell with Bob where I became a post doc in the COCORP Reflection seismic program under the 1988 Penrose medalist Jack Oliver who encouraged our studies of the origin and evolution of the lower crust. At Cornell, I thought I had gone to heaven with daily lunches with colleagues and mentors like 1981 Day medalist Donald Turcotte, 2014 AGU Bucher medalist Brian Isacks, Sidney Kaufman, and Jack Bird. Also at Cornell were Larry Brown, Art Bloom, Dan Karig, Bill Bassett, Terry Jordan, Rick Allmendinger, Bill White, Larry Cathles and Lou Derry. I owe all of these remarkable individuals a huge amount of gratitude.

Being at Cornell brought incredible undergraduate and graduate students who both enriched my life and research. These talented and enthusiastic students worked as colleagues who often lead the way. I particularly mention PhD students Gene Yogodzinski, Gary Citron, James Rubenstone and Jay Romick, and undergrad Susan DeBari who worked in the Aleutians. Among the incredible group in Andean studies were grad students Matt Gorring, Adam Goss, Neil McGlashan, Joe Kato, and Patrick Mulcahy; and undergrads Jeff Abbruzzi and the 2023 AGU VGP Kuno medalist Brenhin Keller. From 1996 to 2015, I had the privilege of teaching and learning from some 175 talented American students in the Cornell/University Buenos Aires Argentine field course, many of whom, including the 2023 Donath medalist Andrew Zuza, are now faculty in top geological sciences programs.

Most importantly, I would not be here without the incredible Argentine and Chilean scientists with whom we worked in the Andean arc and back arc. I am particularly indebted to Victor A. Ramos, Constantino Mpodozis and Beatriz Coira and their families, who have become among my closest friends. I also owe a debt of thanks to Brian Jicha for collaboration on Aleutian studies.

Also importantly, I was introduced to field trips to look for fossils and examine Ordovician strata and Pleistocene glacial deposits by my father Milton Mahlburg, the director of the Rockford, Illinois natural history museum who led me into a life of natural sciences. From Rockford, I went to the University of Illinois where the comradery of my talented classmates in Geology was incredible as we studied and went into the field with mentors like Professors David Anderson, Dennis Wood, and Ralph Langenheim.

To close, I owe a great debt of thanks to my parents, to my husband and closest scientific collaborator Robert Woodbury Kay, and to our children Jennifer Elizabeth and Alexander Marshall, who explored the geological world with us and inspired our research.