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Ian S. E. Carmichael (1930-2011)

The indomitable Ian S. E. Carmichael, who made such a deep and lasting impression on so many of us, with his highly imaginative research career and his legendary mentoring of graduate students, died in Berkeley on August 26th, 2011. Ian applied thermodynamic theory, experiment, and the ground truth of fieldwork to the study of magmatic rocks. Throughout the arc of his career at the University of California at Berkeley, he played a critical role in transforming igneous petrology from a discipline that was largely descriptive to one that is rigorously quantitative, and in the process, he inspired multiple generations of students.

Ian Stuart Edward Carmichael was born on March 29th, 1930 and was raised in Haywards Heath, south of London. He began his education at the age of six when he was packed off to boarding school at Westminster in London. He continued there until his senior year of high school when he made his first trip to the U.S. as an exchange student in Connecticut. Instead of returning home to England for college, he enrolled himself (with the aid of a scholarship) in the Colorado School of Mines, to the surprise and dismay of his parents, and began a lifetime fascination with the rugged terrain of the western United States. After one semester, he returned to England for what was supposed to be a brief Christmas holiday with family, but instead he was promptly drafted into the British army where he saw service in Egypt, Palestine and Sudan. This foray lasted two years, after which he enrolled at Cambridge University, to the delight of his father (E. A. Carmichael, a well-known neurologist at the National Hospital in London). After obtaining his B.A. and M.A. in Geology (specializing in Mineralogy and Petrology) in 1954, Ian went to Canada to prospect for copper in northern Ontario, and then wintered in the Canadian arctic to help survey the Distant Early Warning (DEW) Line. Ian returned to England and took his Ph.D. in 1958 at the Imperial College of Science in the University of London under the supervision of George P. L. Walker. Ian's Ph.D. thesis focused on the Tertiary Thingmuli volcano in eastern Iceland, which he used to address one of the most contentious issues in earth science at the time (before the days of isotope geochemistry and plate tectonics), namely the origin of silicic magma, and whether it could form solely by fractional crystallization of basalt, or whether assimilation of older continental crust was required. The problem went to the very heart of crustal evolution, and Iceland offered a superb opportunity to examine how basaltic magma evolves to rhyolite in the absence of continental crust. The papers from Ian's thesis on the Thingmuli volcanic suite are among his most highly cited among an impressive repertoire.

On the completion of his thesis, Ian became a lecturer at Imperial College. Over the next five years, he began to advise several graduate students (Gloria Borley, Wally Johnson, Tony Beswick, Ian Baker, and Ian Ridley), and he developed an expertise on the crystallization path of feldspars in silicic magmas, an interest (along with motor racing) that he shared with Professor William S. MacKenzie ('Mac' to Ian). The two friends wrote the first (funded) proposal to build an experimental petrology laboratory in the U.K. to study feldspar crystallization. In 1963, Ian had the opportunity to take a 6-month leave to visit the University of Chicago, where J.V. Smith was showcasing one of the very first electron microprobes. This instrument had enormous appeal to Ian, who was spending most of his time performing tedious mineral separations for wet chemical analysis. Electron microprobes were not terribly reliable in 1963, and after six months Ian did not have all the data he wanted, and so he submitted a request to Imperial College to extend his leave for a few more months. The request was promptly denied, and he was ordered to return to England forthwith. Ian was so strongly motivated to obtain additional data that he simply quit his faculty job on the spot. So there he was, at age 34, with a wife and three young children, in Chicago, in the dead of winter, without a job (but with a few more analyses!). It was not long before he was invited to UC Berkeley to give a lecture. In February, flying out from Chicago, Berkeley must have looked like Paradise. Given the year, 1964, visions of David Lodge's book, 'Changing Places' cannot help but pop in our heads. Needless to say, this trip to Berkeley eventually translated into a tenured position as an associate professor.

When Ian first arrived on the Berkeley campus in 1964, the study of magmatic rocks was largely descriptive. In contrast, the questions that he was posing, well before their time, were whether the crystals in erupted lavas could be used to reveal the temperature, pressure, dissolved water concentration, and oxidation state of the magmatic liquids from which they crystallized. These questions required a thermodynamic approach, which was a reasonably developed tool in the field of metamorphic petrology, but nearly non-existent for igneous petrologists studying crystal-liquid equilibrium. The problem was the lack of information on the thermodynamic properties of magmatic liquids under in-situ high-temperature conditions. Thus the barrier to the quantitative study of magmatic rocks was immense throughout the 1960's and 70's. Although Ian arrived at Berkeley with little training in thermodynamics, he soon rectified matters by sitting in on some thermodynamics courses in the chemistry department, working on problem sets and exams side by side with his graduate students (Jim Nicholls, Alan Smith, Barbara Nash, and Jay Stormer) and interacting with visitors such as Bernie Wood and Roger Powell. Even more influential for Ian was a course on high-temperature thermodynamics in the materials science department, which introduced him to the Berkeley Thermodynamic Center where there was a high-temperature drop calorimeter. There, Ian and his student Charlie Bacon began some of the first measurements of the enthalpy of various silicate glasses and liquids. It was not long before the 'moth-balled' drop calorimeter was moved into Ian's laboratory, and his student Jonathan Stebbins began to systematically obtain enthalpy and heat capacity data for high-temperature silicate liquids. Soon after, Ian pursued a parallel program (with students Steve Nelson, Mark Rivers, Dan Stein, Quentin Williams, Becky Lange, Victor Kress, and visiting scholar Xuanxue Mo) to measure the volumetric properties of silicate liquids, including their compressibility from sound speed measurements. Later, he worked with his student Don Snyder to measure the thermal conductivity of silicate liquids. Thus began a highly productive period throughout the 1970's and 80's where several papers on the thermodynamics of magmatic reactions and the properties of silicate melts were published.

A unique skill that Ian brought to his experimental work on the thermodynamic properties of liquids, as well as numerous field studies, was his classical training in the art of 'wet' chemical analysis, which he taught to several of his students. Before the days of the XRF, ICP-MS and electron microprobe, wet chemistry was the only method to obtain compositional analyses for bulk rocks and mineral separates. However, the quality of wet chemical analyses depended entirely on the skill of the practitioner, and Ian was a well-known virtuoso! Ian's skill was particularly useful when his research group developed general models for the calculation of density, heat capacity and other liquid properties as a function of composition. Because the precision of Ian's wet chemical analyses for the major elements often exceeded what could be achieved by other methods, the errors on fitted partial molar quantities were substantially reduced. Ian also created dozens of new standards for UC Berkeley's electron microprobe over the years through his wet chemical analyses.
In the 1980's, Ian made his only foray into the spectroscopy of silicate liquids. Prior to 1985, the only way to study the microscopic structure of silicate liquids was to apply spectroscopy to quenched glasses as a proxy model. However, the abrupt jump in heat capacity at the glass-liquid transition is a testament to the fundamental difference between glasses and liquids. In order to identify the configurational changes that occur as a glass is heated to a liquid, Ian worked with Jonathan Stebbins and post-doc Jim Murdoch to build an apparatus to measure the NMR (nuclear magnetic resonance) spectra of silicate liquids at high temperature. These measurements were the first to be performed under in-situ conditions and were critical for identifying the dynamic and continuous breaking of bonds that occurs in liquids, which led to a deeper understanding of why the thermodynamic properties of liquids differ from glasses and also provided insights into the mechanisms of viscous transport in melts.

For Ian, the thermodynamic property data were never a goal unto itself, and it was the application of these data to volcanic rocks through a thermodynamic model that fully captured his imagination. With his student, Mark Ghiorso, the first version of a crystal-liquid thermodynamic model applicable to magmatic systems was published in 1983. Mark Ghiorso has continued to develop this model over the ensuing decades into the widely used MELTS software package. Thus Ian's research efforts throughout the 1970's and 80's were critical to the development of subsequent thermodynamic models of crystal-liquid equilibrium, which are at the core of modern igneous petrology. They provide the only means to rigorously quantify a variety of magmatic reactions, including decompressional melting of the mantle under isentropic conditions, the assimilation of a solid assemblage by a crystallizing magma, and the oxygen gain or loss in a cooling magma, just to name a few.

It was during the early development of this general thermodynamic model that Ian realized it was necessary to quantify how ferric-ferrous ratios in magmatic liquids responded to oxygen fugacity, temperature and pressure, as the fO2 of a magma can alter its crystallization path. This spawned yet another series of experiments throughout the 1980's with post-doc Richard Sack, visiting professor Attila Kilinc, and graduate student Victor Kress, and once again Ian's wet chemical skills (this time in analyzing ferrous iron concentrations, distinct from total iron) were critical to the success of these papers. From this effort has come the ability to calculate the oxidation state of any fresh, volcanic rock. This led Ian to publish a landmark paper (Carmichael, 1991) in which he showed that the range in oxygen fugacity of mantle-derived lavas varies by several orders of magnitude. The most reduced magmas are those erupted at mid-ocean spreading ridges and the most oxidized are those erupted at subduction zones with the strongest enrichment in the arc geochemical signature, namely minettes. This range in the fO2 of mantle-derived lavas exceeds that observed in samples of spinel lherzolite, and this provided Ian with key evidence that if the mantle source region for minettes includes veins of phlogopite-pyroxenite in a lherzolite matrix, then these veins must be exceptionally oxidized, which in turn points to the highly oxidized nature of fluids that are derived from subducted slabs.

Throughout this period of time, in which Ian was making tremendous strides on the thermodynamics of magmatic systems, he was consistently pursuing field-based studies with his students. Ian always had a particular fascination with highly alkaline lavas, both because they are relatively rare and thus unusual, and also because of their diverse phenocryst assemblages, which leant themselves to Ian's earliest attempts to use thermodynamics to reveal the full range of silica activity in magmas. In the 1960's and 70's, Ian's field expeditions took him throughout the western U.S. with his students Jim Nicholls, Alan Smith, Barbara Nash, Jay Stormer and Frank Spera, as well as to far-flung locales (to Africa with Frank Brown, to the Aleutians with Bruce Marsh, and to New Guinea with Garry Lowder and Robert Heming). Ian also traveled to New Zealand, which in turn led Tony Ewart to spend a year at Berkeley in the mid-1970s. At this time, Ian began to work closer to home, as his student Wes Hildreth unraveled the erupted products of the Long Valley caldera, namely the Bishop Tuff in eastern California. Ian's failed efforts to raise National Science Foundation (NSF) funding for this project led him to often say, 'Never get discouraged if you are turned down twice by NSF, because this probably means you are on to something!' This was the case for Ian as the Long Valley magmatic system and its erupted products are now among the most intensively studied and well funded by NSF of any comparable volcanic center in the world. Also in the 1970's, one of Ian's students, Steve Nelson, made the first foray down to Mexico, and was followed soon after by Gail Mahood. For the next 30 years, Ian's field-based research moved to the Mexican volcanic arc, where at least 8 more students had projects (Jim Luhr, Toshi Hasenaka, Jamie Allan, Becky Lange, Paul Wallace, Kevin Righter, Gordon Moore, Dawnika Blatter) and where he befriended several Mexican colleagues, including Hugo Delgado Granados. Ian brought nearly 40 UC Berkeley undergraduates down to Mexico, who served as field assistants over the decades that Ian ran his field program there.

Ian's research in the Mexican volcanic arc, a classic subduction zone (and staging area for the growth and evolution of continental crust), led him to begin a program throughout the 1990's to quantify the role of H2O in magmatic processes through experiments with an internally heated pressure vessel. With his students Kevin Righter, Gordon Moore, Dawnika Blatter, and post-doc, Jenni Barclay, he provided fully characterized phase diagrams applicable to the upper crust for a range of arc magmas (basalt to andesite), and, with Gordon Moore, performed a systematic study of water solubility in natural liquids covering a wide compositional range, which led to the first general model of water solubility applicable to most magmatic compositions. In a paper that is rapidly becoming a classic (Carmichael, 2002), where the phrase 'andesite aqueduct' is used in the title, Ian is among the earliest proponents of the concept that the crystallization of rapidly ascending arc magmas through the upper crust is driven largely by degassing and not by cooling, which at the time ran counter to conventional thinking. It was also at this time that he developed collaborations with Chuck DeMets and Joann Stock, encouraging them in their geophysical studies of the tectonics of western Mexico.

One of the most powerful aspects of Ian's approach to the study of magmatic rocks was the consistent interplay between theory, experiment, and field studies. This gave Ian insight into what are the most pressing experiments to perform and how they can be most effectively applied to examples in the rock record. This probably explains why Ian's numerous publications have a combined number of citations that exceeds 12,000 and why he has an h-index that exceeds 60, both of which demonstrate the depth and breadth of his impact. He has been widely recognized for his research achievements through the Bowen Award (American Geophysical Union), the Day Medal (Geological Society of America), the Murchison Medal (Geological Society of London), the Schlumberger Medal (Mineralogical Society of Great Britain), and the Roebling Medal (Mineralogical Society of America). He was a Fellow of the Royal Society of London, in addition to being a Fellow in the Geochemical Society, the Geological Society of America, the Mineralogical Society of America and the American Geophysical Union.

What is particularly impressive about Ian Carmichael's research record and mentoring of students is that it was achieved while he was deeply involved with university administration and editorial duties. Ian was surely the embodiment of the saying: If you want something done, give it to a busy person. For 15 years (1985-2000), he was both an Associate Dean and an Associate Provost on the Berkeley campus with a ≥ 50% appointment. Prior to that, he had two tours of duty (1972-76; 1980-82) as Chair of the Department of Geology and Geophysics (now Earth and Planetary Science), plus a two-year stint (1976-78) as an Associate Dean in the Graduate Division. From 1973-1990, he was Editor-in-Chief of Contributions to Mineralogy and Petrology, and for another 14 years afterward he continued as an Associate Editor. In the early 1970's, Ian found the time to write a textbook, Igneous Petrology (Carmichael, Turner and Verhoogen, 1974), which remained a classic for decades. In 1996, while Ian was still an Associate Dean and Provost, he started an appointment as the Director of the Lawrence Hall of Science, UC Berkeley's public science center, which he continued for seven years. During this same time period, from 1996-1998, he was also Acting Director of the Botanical Gardens at UC Berkeley. Throughout all of this intensive and consuming administration that spanned three decades, Ian maintained a continuous series of active research grants funded by the National Science Foundation (and for much of the time, by the Department of Energy as well).

Perhaps it was because Ian was so busy with administrative duties that his time spent with students - thinking about the rocks - was so treasured. Despite two rather bum knees (derived from too many jumps during his paratrooping days in the British army), Ian often found the time to teach summer field camp to Berkeley undergraduates. And I should mention that, at the time, Berkeley faculty were not compensated in any way, financially or otherwise, for teaching camp. Ian particularly valued his time with graduate students, which often began with the long-standing tradition of morning coffee. A morning chat with Ian and his vast imagination, five days a week for 4-5 years, left its mark on his graduate students. The other tradition was Ian's evening seminars. When I was a student, these occurred every Tuesday: fall, winter, spring, summer. They knew no semester bounds, had no official course number, no credit hours. The event began with a 6 p.m. Chinese dinner across the street, and then we would troop back to the department for a seminar that usually began by 7:30 p.m. and was known to run till 11 p.m. and beyond. If you were the speaker, there was no such thing as being 'saved by the bell.' Looking back, I have never known a more demanding and probing audience when giving a lecture.

There is no doubt that Ian's greatest reputation was as a graduate advisor, who produced an extraordinary number of successful Ph.D. students. And it is not just their success, but also the diversity of what each of them does, that is so striking. Just about every aspect of the study of magmatism was pursued by Ian's students: from igneous field geology and experimental petrology to magma physics and thermodynamic modeling of melts and minerals - the Ph.D. theses of Ian's students span the spectrum. So what was Ian's secret? One factor was surely his creative and fertile imagination, as well as his infectious enthusiasm for the thrill that comes with discovery and achievement. He had a way of making the work we were engaged in seem deeply urgent, important, and exciting; a common refrain was, 'If it's worth doing, it was worth doing yesterday!' But perhaps the key ingredient was Ian's intellectual generosity, where he continuously and freely shared his ideas with his students - thrilled to see them run with it and become the one identified with it.

For all of us who crossed paths with Ian, he left an indelible mark. None of us escaped being shaped, in some way, by the hurricane force of his personality. For many of us, not just those of us who were his students, his exuberant pushing and prodding forced us to stretch ourselves and realize potentials we never knew we had. For this, Ian will be sorely missed and never forgotten.

Ian is survived by many loved ones, including his daughter Deborah Carmichael of Concord, California, his son Graham Carmichael of Tucson, Arizona, his daughter Anthea Carmichael of Berkeley, California, and his six grandchildren, Andrea, Colleen, Alexander, Olivia, Ian, and Calvin. His son, Alistair, predeceased him.

Rebecca Lange (University of Michigan)
October 2011

UC Berkeley Ph.D. students of Ian S. E. Carmichael (29):
J Nicholls, 1969 (U. Calgary); AL Smith, 1969 (Cal State U., San Bernadino); GG Lowder, 1970 (Malachite Resources, Australia); FH Brown, 1971 (U. Utah); WP Nash, 1971 (U. Utah); JC Stormer, 1971 (Rice U., emeritus); RF Heming, 1973 (consultant); BD Marsh, 1974 (Johns Hopkins U.); CR Bacon, 1975 (USGS); EW Hildreth, 1977 (USGS); FJ Spera, 1977 (UC Santa Barbara); SA Nelson, 1979 (Tulane U.); GA Mahood, 1979 (Stanford U.); MS Ghiorso, 1979 (OFM Research); K Kyser, 1979 (Queen's U., Canada); D Bice, 1980 (consultant); D Kosco, 1980 (lawyer); JF Luhr, 1980 (Smithsonian; deceased); JF Stebbins, 1983 (Stanford U.); ML Rivers, 1985 (U. Chicago); G Lux, 1985 (Charles Evans Inc.); T Hasenaka, 1986 (Kumamoto U., Japan); RA Lange, 1989 (U. Michigan); VC Kress, 1990 (U. Washington); D Snyder, 1991 (RAND Corporation); PJ Wallace, 1991 (U. Oregon); K Righter, 1994 (NASA Johnson Space Center); G Moore, 1997 (Arizona State U.); DL Blatter, 1998 (USGS)