Academic Appointments


Administrative Appointments


  • Geoarchaeologist, Proyecto Arqueologico Copan, Honduras (1978 - 1978)
  • Assistant Professor of Geology, Stanford University (1979 - 1987)
  • Visiting Assistant Professor Dept. of Geosciences,, Pennsylvania State University (1983 - 1983)
  • Associate Professor of Geology, Stanford University (1987 - 1993)
  • Visiting Assoc. Professor Dept. of Geological Sciences, University of Michigan (1989 - 1989)
  • Professor, Department of Geological & Environmental Sciences, Stanford University (1993 - Present)

Boards, Advisory Committees, Professional Organizations


  • Member, SES Space Allocation and Use Committee, SES, Stanford University (2011 - Present)
  • Faculty leader, Stanford Alumni Association trip to Mongolia, Stanford Alumni Association (2011 - 2011)
  • Chair, Reappointment Committee for Assistant Professor Kate Maher, GES, Stanford University (2011 - 2011)
  • Member, Search Committee, Head Earth Sciences Librarian, Stanford University (2010 - 2011)
  • Co-Chair, GES Search Committee for Geochronologist, GES, Stanford University (2006 - 2008)
  • Associate Vice Provost for Graduate Education, Stanford University (2006 - 2007)
  • Member, Review Committee on future of Stanford-USGS Microanalytical Center, Stanford University, USGS (2006 - 2007)
  • Associate Dean for Graduate Policy, Stanford University (2005 - 2006)
  • Member, Steering Committee of the Faculty Senate, Stanford University (2005 - 2006)
  • Member, Faculty Senate, Stanford University (2005 - 2007)
  • Member, Provost’s Diversity Cabinet, Stanford University (2005 - 2006)
  • Member, Committee on Graduate Studies, Stanford University (2005 - 2006)
  • Member, Executive Committee, Archaeology Center, Stanford University (2004 - 2008)
  • Member, Subcommittee on University Honors, Stanford University (2004 - 2004)
  • GES Graduate Student Coordinator, GES, Stanford University (2004 - 2005)
  • Member, Board of Trustees Committee on Land and Buildings, Stanford University (2003 - 2005)
  • Faculty leader, Stanford Alumni Travel trip to Baja California, Stanford Alumni Association (2002 - 2002)
  • Chair, Search Committee for Academic Secretary, Stanford University (2002 - 2002)
  • Member, Advisory committee on the Institute for Research on Women and Gender, Stanford University (2001 - 2002)
  • Member, Committee on Faculty Diversity, Stanford University (2001 - 2004)
  • Member, Executive Committee, Interdisciplinary Program in Archeology, Stanford University (2000 - 2004)
  • Member, NCAA Compliance Committee (intercollegiate athletics), Stanford University (2000 - 2001)
  • Faculty leader, Stanford Alumni Travel trip to Baja and Copper Canyon, Stanford Alumni Association (2000 - 2000)
  • Faculty leader, Stanford Alumni Travel trip to southeast Alaska, Stanford Alumni Association (1999 - 1999)
  • Member, Academic Standing Committee (considers cases of students in academic difficulty), Stanford University (1999 - 2002)
  • Member, Faculty Steering Committee on the Campaign for Undergraduate Education, Stanford University (1999 - 2003)
  • Member, Committee on Nominations, Stanford Board of Trustees, Stanford University (1997 - 1999)
  • Member, Search committee, Assistant University Librarian for Collection Development, Stanford University (1997 - 1998)
  • Member, Search committee for Assistant University Librarian, Stanford University (1997 - 1997)
  • External Reviewer, Dept. of Earth Sciences, Dalhousie University, Halifax, Canada, Dalhousie University (1997 - 1997)
  • Associate Editor, Bulletin, Geological Society of America (1997 - 2000)
  • Member, Subcommittee on Fiscal Integrity, Self-Study for NCAA Certification, Stanford University (1997 - 1998)
  • Member, Faculty Senate Planning and Policy Board, Stanford University (1996 - 1999)
  • Member (Vice Chair, 1997-98, 1999-2000; Chair 2000-2001) Advisory Board (7-member board that reviews all appointments, promotions, dismissals, dissolutions of departments, etc.), Stanford University (1996 - 2001)
  • Member, Audit Committee, Geological Society of America (1996 - 1999)
  • Chair, Department of Geological and Environmental Sciences, GES, Stanford University (1996 - 1998)
  • Councillor, Geological Society of America (1996 - 1999)
  • Chair, Faculty Senate, Stanford University (1995 - 1996)
  • Congressional testimony concerning the role of the U.S. Geological Survey, Stanford University (1995 - 1995)
  • Instructor, Stanford Sophomore College, Stanford University (1995 - 1998)
  • Member, UPS Endowment Advisory Committee to Provost, Stanford University (1994 - 1998)
  • Member, "Ungroup", Provost's advisory committee on budget and strategic planning, Stanford University (1994 - 1998)
  • Member, Design Committee, Science Core for Nonscientists, Stanford University (1994 - 1995)
  • Member, Review Committee, Program on Writing and Critical Thinking, Stanford University (1994 - 1994)
  • Member, Steering Committee of the Faculty Senate, Stanford University (1994 - 1996)
  • Co-Chair, GES Graduate Admissions Committee, GES, Stanford University (2012 - Present)
  • Member, Steering Committee of Program in Earth Systems, Stanford University (1994 - 1999)
  • Chair, Advisory Group on Sponsored Projects Administration, Stanford University (1994 - 1994)
  • Member, President's Commission on Undergraduate Education, Stanford University (1993 - 1994)
  • Member, Faculty Senate, Stanford University (1992 - 1996)
  • Member, Stanford Judicial Council, Stanford University (1990 - 2004)
  • Associate Chair, Department of Geological and Environmental Sciences, GES, Stanford University (1990 - 1995)

Professional Education


  • Ph.D., University of California, Geology (1980)
  • M.A., University of California, Geology (1976)
  • A.B., University of California, Geology (1974)

Current Research and Scholarly Interests


Research
I am interested in understanding the processes that assemble and occur in the bodies of silicic magma that give rise to huge, explosive eruptions that spread ash continent-wide. My students and I study young volcanoes to determine how large and how explosive future eruptions might be, how frequently they are likely to occur, and what mechanisms trigger eruptions. We also do field-based studies in mountainous areas where plutons and the guts of volcanoes are well-exposed, mapping them and then analyzing their products in the laboratory, in order to reconstruct the life histories of these systems. To these ends we make extension use of 40-39Ar geochronology and use the Stanford-USGS ion probe to determine U-Pb and U-series ages. The main foci of our current research are (1) widespread Mid-Miocene silicic volcanism and calderas associated with the Columbia River flood basalts; (2) controls on the pre-eruptive concentrations of energy-critical elements in silicic magmas as evidenced by melt inclusions; (3) petrologic evidence for volcanic hazards in the Long Valley--Mammoth Mountain--Mono Craters--Mono Basin region; and (4) volcanic hazards of western Saudi Arabia at Harrat Rahat and petrologic study of the origin of trachytes associated with young basaltic lavas. I also have an interest in geoarchaeology, especially in the application of petrologic and geochemical techniques to determining the provenance of obsidian and ceramics.

Teaching
I teach an introductory physical geology course that culminates in a field trip to Death Valley and the eastern Sierra Nevada. My upper-division-level course on volcanology includes a field trip to young volcanism of the eastern Sierra Nevada (Long Valley, Mammoth Mountain, Mono Craters, Mono Lake). I teach a graduate-level course on igneous petrogenesis, and field seminars in physical volcanology of the southern Cascade arc and transform-related volcanism in the Coast Range of California, as well as specialized graduate seminars in petrology and physical volcanology from time to time.

Professional Activities
Associate Vice Provost for Graduate Education (2006-07); Associate Dean for Graduate Policy (2005-06); Member, Faculty Steering Committee, Campaign for Undergraduate Education (2000-05); Member, Executive Committee, Interdisciplinary Program in Archaeology (2000-2008); Faculty leader, Stanford Alumni trip to Mongolia

Projects


  • Volcanic hazards of Harrat Rahat, western Saudi Arabia, cooperative study with the U.S. Geological Survey and the Saudi Geologic Survey

    Location

    Medinah, Saudi Arabia

  • Magma mixing as a trigger for silicic eruptions in Long Valley and Mono Basin, Stanford University, U.S. Geological Survey

    Location

    Mammoth Lakes, CA

  • Widespread Mid-Miocene rhyolitic magmatism associated with flood basalts in western U.S., Stanford University

    Location

    Denio, Nevada

  • Controls on concentrations of energy-critical elements in rhyolitic magmas, Stanford University, U.S. Geological Survey

    Location

    Stanford, CA

  • Timing of Mid-Miocene climate events relative to flood basalt and rhyolite eruptions in the Pacific Northwest, Stanford University

    Location

    southeastern Oregon, northern Nevada, western Idaho

2018-19 Courses


All Publications


  • Lithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins NATURE COMMUNICATIONS Benson, T. R., Coble, M. A., Rytuba, J. J., Mahood, G. A. 2017; 8: 1-9

    Abstract

    The omnipresence of lithium-ion batteries in mobile electronics, and hybrid and electric vehicles necessitates discovery of new lithium resources to meet rising demand and to diversify the global lithium supply chain. Here we demonstrate that lake sediments preserved within intracontinental rhyolitic calderas formed on eruption and weathering of lithium-enriched magmas have the potential to host large lithium clay deposits. We compare lithium concentrations of magmas formed in a variety of tectonic settings using in situ trace-element measurements of quartz-hosted melt inclusions to demonstrate that moderate to extreme lithium enrichment occurs in magmas that incorporate felsic continental crust. Cenozoic calderas in western North America and in other intracontinental settings that generated such magmas are promising new targets for lithium exploration because lithium leached from the eruptive products by meteoric and hydrothermal fluids becomes concentrated in clays within caldera lake sediments to potentially economically extractable levels.Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.

    View details for DOI 10.1038/s41467-017-00234-y

    View details for PubMedCentralID PMC5559592

  • Geology of the High Rock caldera complex, northwest Nevada, and implications for intense rhyolitic volcanism associated with flood basalt magmatism and the initiation of the Snake River Plain-Yellowstone trend GEOSPHERE Coble, M. A., Mahood, G. A. 2016; 12 (1): 58-113

    View details for DOI 10.1130/GES01162.1

    View details for Web of Science ID 000369539200005

  • Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH Benson, T. R., Mahood, G. A. 2016; 309: 96-117
  • Initial impingement of the Yellowstone plume located by widespread silicic volcanism contemporaneous with Columbia River flood basalts GEOLOGY Coble, M. A., Mahood, G. A. 2012; 40 (7): 655-658

    View details for DOI 10.1130/G32692.1

    View details for Web of Science ID 000305818900020

  • Silicic calderas in arc settings: Characteristics, distribution, and tectonic controls GEOLOGICAL SOCIETY OF AMERICA BULLETIN Hughes, G. R., Mahood, G. A. 2011; 123 (7-8): 1577-1595

    View details for DOI 10.1130/B30232.1

    View details for Web of Science ID 000291248800020

  • Strontium Isotopic Evidence for Prehistoric Transport of Gray-Ware Ceramic Materials in the Eastern Grand Canyon Region, USA GEOARCHAEOLOGY-AN INTERNATIONAL JOURNAL Carter, S. W., Wiegand, B., Mahood, G. A., Dudas, F. O., Wooden, J. L., Sullivan, A. P., Bowring, S. A. 2011; 26 (2): 189-218

    View details for DOI 10.1002/gea.20348

    View details for Web of Science ID 000287371900002

  • New Ar-40/Ar-39 ages reveal contemporaneous mafic and silicic eruptions during the past 160,000 years at Mammoth Mountain and Long Valley caldera, California GEOLOGICAL SOCIETY OF AMERICA BULLETIN Mahood, G. A., Ring, J. H., Manganelli, S., McWilliams, M. O. 2010; 122 (3-4): 396-407

    View details for DOI 10.1130/B26396.1

    View details for Web of Science ID 000274210600004

  • Tectonic controls on the nature of large silicic calderas in volcanic arcs GEOLOGY Hughes, G. R., Mahood, G. A. 2008; 36 (8): 627-630

    View details for DOI 10.1130/G24796A.1

    View details for Web of Science ID 000258017700009

  • New ages for the climactic eruptions at Yellowstone: Single-crystal Ar-40/Ar-39 dating identifies contamination GEOLOGY Gansecki, C. A., Mahood, G. A., McWilliams, M. 1998; 26 (4): 343-346
  • Seeing past the effects of re-equilibration to reconstruct magmatic gradients in plutons: La Gloria Pluton, central Chilean Andes CONTRIBUTIONS TO MINERALOGY AND PETROLOGY CORNEJO, P. C., Mahood, G. A. 1997; 127 (1-2): 159-175
  • Ar-40/Ar-39 geochronology of rhyolites erupted following collapse of the Yellowstone caldera, Yellowstone Plateau volcanic field: Implications for crustal contamination EARTH AND PLANETARY SCIENCE LETTERS Gansecki, C. A., Mahood, G. A., McWilliams, M. O. 1996; 142 (1-2): 91-107
  • Zoning patterns and petrologic processes in peraluminous magma chambers: Hall canyon pluton, Panamint mountains, California GEOLOGICAL SOCIETY OF AMERICA BULLETIN Mahood, G. A., Nibler, G. E., Halliday, A. N. 1996; 108 (4): 437-453
  • ISOTOPIC CONSTRAINTS ON THE PRODUCTION-RATES, CRYSTALLIZATION HISTORIES AND RESIDENCE TIMES OF PRE-CALDERA SILIC MAGMAS, LONG VALLEY, CALIFORNIA EARTH AND PLANETARY SCIENCE LETTERS Davies, G. R., Halliday, A. N., Mahood, G. A., Hall, C. M. 1994; 125 (1-4): 17-37
  • THE OCCURRENCE AND DISTRIBUTION OF MO AND MOLYBDENITE IN UNALTERED PERALKALINE RHYOLITES FROM PANTELLERIA, ITALY CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Lowenstern, J. B., Mahood, G. A., Hervig, R. L., Sparks, J. 1993; 114 (1): 119-129
  • FLUID INCLUSIONS IN XENOLITHS YIELD EVIDENCE FOR FLUID EVOLUTION IN PERALKALINE GRANITIC BODIES AT PANTELLERIA (ITALY) JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH DeVivo, B., Frezzotti, M. L., Mahood, G. 1992; 52 (4): 295-301
  • EVIDENCE FOR ASCENT OF DIFFERENTIATED LIQUIDS IN A SILICIC MAGMA CHAMBER FOUND IN A GRANITIC PLUTON 2ND HUTTON SYMP ON THE ORIGIN OF GRANITES AND RELATED ROCKS Mahood, G. A., CORNEJO, P. C. ROYAL SOC EDINBURGH. 1992: 63–69
  • PETROGENESIS OF HIGH-SILICA RHYOLITE ON THE ALASKA PENINSULA GEOPHYSICAL RESEARCH LETTERS Lowenstern, J. B., Mahood, G. A. 1991; 18 (8): 1565-1568
  • EVIDENCE FOR EXTREME PARTITIONING OF COPPER INTO A MAGMATIC VAPOR-PHASE SCIENCE Lowenstern, J. B., Mahood, G. A., Rivers, M. L., Sutton, S. R. 1991; 252 (5011): 1405-1409

    Abstract

    The discovery of copper sulfides in carbon dioxide- and chlorine-bearing bubbles in phenocryst-hosted melt inclusions shows that copper resides in a vapor phase in some shallow magma chambers. Copper is several hundred times more concentrated in magmatic vapor than in coexisting pantellerite melt. The volatile behavior of copper should be considered when modeling the volcanogenic contribution of metals to the atmosphere and may be important in the formation of copper porphyry ore deposits.

    View details for Web of Science ID A1991FP86800027

    View details for PubMedID 17772911

  • DEVELOPMENT OF THE LONG VALLEY, CALIFORNIA, MAGMA CHAMBER RECORDED IN PRECALDERA RHYOLITE LAVAS OF GLASS MOUNTAIN CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Metz, J. M., Mahood, G. A. 1991; 106 (3): 379-397
  • TRACE-ELEMENT PARTITIONING IN PANTELLERITES AND TRACHYTES GEOCHIMICA ET COSMOCHIMICA ACTA Mahood, G. A., Stimac, J. A. 1990; 54 (8): 2257-2276
  • EVIDENCE FOR LONG RESIDENCE TIMES OF RHYOLITIC MAGMA IN THE LONG VALLEY MAGMATIC SYSTEM - THE ISOTOPIC RECORD IN PRECALDERA LAVAS OF GLASS MOUNTAIN EARTH AND PLANETARY SCIENCE LETTERS Halliday, A. N., Mahood, G. A., Holden, P., Metz, J. M., Dempster, T. J., Davidson, J. P. 1989; 94 (3-4): 274-290
  • MECHANICAL MODELS FOR CORRELATION OF RING-FRACTURE ERUPTIONS AT PANTELLERIA, STRAIT OF SICILY, WITH GLACIAL SEA-LEVEL DRAWDOWN BULLETIN OF VOLCANOLOGY WALLMANN, P. C., Mahood, G. A., Pollard, D. D. 1988; 50 (5): 327-339
  • PHYSICAL AND CHEMICAL-MODELS OF ZONED SILICIC MAGMAS - THE LOMA SECA TUFF AND CALABOZOS CALDERA, SOUTHERN ANDES JOURNAL OF PETROLOGY Grunder, A. L., Mahood, G. A. 1988; 29 (4): 831-867
  • GENERATION OF HIGH-SILICA RHYOLITE - A ND, SR, AND O ISOTOPIC STUDY OF SIERRA-LA-PRIMAVERA, MEXICAN NEOVOLCANIC BELT CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Mahood, G. A., Halliday, A. N. 1988; 100 (2): 183-191
  • FIELD, CHEMICAL, AND PHYSICAL CONSTRAINTS ON MAFIC-FELSIC MAGMA INTERACTION IN THE LAMARCK GRANODIORITE, SIERRA-NEVADA, CALIFORNIA GEOLOGICAL SOCIETY OF AMERICA BULLETIN FROST, T. P., Mahood, G. A. 1987; 99 (2): 272-291
  • COMPOSITIONAL LAYERS IN THE ZONED MAGMA CHAMBER OF THE GRIZZLY PEAK TUFF GEOLOGY Fridrich, C. J., Mahood, G. A. 1987; 15 (4): 299-303
  • STRONG COMPOSITIONAL ZONATION IN A SILICIC MAGMATIC SYSTEM - LOS-HUMEROS, MEXICAN NEOVOLCANIC BELT JOURNAL OF PETROLOGY FERRIZ, H., Mahood, G. A. 1987; 28 (1): 171-209
  • RING-FRACTURE ERUPTION OF THE BISHOP TUFF GEOLOGICAL SOCIETY OF AMERICA BULLETIN Hildreth, W., Mahood, G. A. 1986; 97 (4): 396-403
  • RISE AND FALL OF A BASALT-TRACHYTE-RHYOLITE MAGMA SYSTEM AT THE KANE-SPRINGS WASH CALDERA, NEVADA CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Novak, S. W., Mahood, G. A. 1986; 94 (3): 352-373
  • EXPERIMENTAL CONSTRAINTS ON DEPTHS OF FRACTIONATION OF MILDLY ALKALIC BASALTS AND ASSOCIATED FELSIC ROCKS - PANTELLERIA, STRAIT OF SICILY CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Mahood, G. A., Baker, D. R. 1986; 93 (2): 251-264
  • PERALKALINE AND METALUMINOUS MIXED-LIQUID IGNIMBRITES OF THE GUADALAJARA REGION, MEXICO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH Mahood, G. A., Gilbert, C. M., Carmichael, I. S. 1985; 25 (3-4): 259-271
  • CORRELATION OF ASH-FLOW TUFFS GEOLOGICAL SOCIETY OF AMERICA BULLETIN Hildreth, W., Mahood, G. 1985; 96 (7): 968-974
  • VOLCANIC STRATIGRAPHY OF THE LOS AZUFRES GEOTHERMAL AREA, MEXICO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH Dobson, P. F., Mahood, G. A. 1985; 25 (3-4): 273-287
  • PRECURSORS TO THE BISHOP TUFF ERUPTION - GLASS MOUNTAIN, LONG VALLEY, CALIFORNIA JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS Metz, J. M., Mahood, G. A. 1985; 90 (NB13): 1121-1126
  • ERUPTION RATES AND COMPOSITIONAL TRENDS AT LOS-HUMEROS-VOLCANIC-CENTER, PUEBLA, MEXICO JOURNAL OF GEOPHYSICAL RESEARCH FERRIZ, H., Mahood, G. A. 1984; 89 (NB10): 8511-8524
  • REVERSE ZONING IN THE RESURGENT INTRUSIONS OF THE GRIZZLY PEAK CAULDRON, SAWATCH RANGE, COLORADO GEOLOGICAL SOCIETY OF AMERICA BULLETIN Fridrich, C. J., Mahood, G. A. 1984; 95 (7): 779-787
  • PYROCLASTIC ROCKS AND CALDERAS ASSOCIATED WITH STRONGLY PERALKALINE MAGMATISM JOURNAL OF GEOPHYSICAL RESEARCH Mahood, G. A. 1984; 89 (NB10): 8540-8552
  • LARGE PARTITION-COEFFICIENTS FOR TRACE-ELEMENTS IN HIGH-SILICA RHYOLITES GEOCHIMICA ET COSMOCHIMICA ACTA Mahood, G., Hildreth, W. 1983; 47 (1): 11-30
  • NESTED CALDERAS AND TRAPDOOR UPLIFT AT PANTELLERIA, STRAIT OF SICILY GEOLOGY Mahood, G., Hildreth, W. 1983; 11 (12): 722-726
  • A RECONNAISSANCE GEOCHEMICAL STUDY OF LA-PRIMAVERA GEOTHERMAL AREA, JALISCO, MEXICO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH Mahood, G. A., Truesdell, A. H., TEMPLOS, L. A. 1983; 16 (3-4): 247-261
  • K-AR DATING YOUNG RHYOLITIC ROCKS - A CASE-STUDY OF THE SIERRA-LA-PRIMAVERA, JALISCO, MEXICO GEOLOGICAL SOCIETY OF AMERICA BULLETIN Mahood, G. A., Drake, R. E. 1982; 93 (12): 1232-1241
  • A SUMMARY OF THE GEOLOGY AND PETROLOGY OF THE SIERRA LA PRIMAVERA, JALISCO, MEXICO JOURNAL OF GEOPHYSICAL RESEARCH Mahood, G. A. 1981; 86 (NB11): 137-152
  • CHEMICAL EVOLUTION OF A PLEISTOCENE RHYOLITIC CENTER - SIERRA-LA-PRIMAVERA, JALISCO, MEXICO CONTRIBUTIONS TO MINERALOGY AND PETROLOGY Mahood, G. A. 1981; 77 (2): 129-149