Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter June 20, 2019

A low-aluminum clinopyroxene-liquid geothermometer for high-silica magmatic systems

Karalee K. Brugman and Christy B. Till
From the journal American Mineralogist


Several geothermobarometric tools have focused on clinopyroxene due to its prevalence in igneous rocks, however clinopyroxene produced in high-silica igneous systems is high in iron and low in aluminum, causing existing geothermometers that depend on aluminum exchange to fail or yield overestimated temperatures. Here we present a new clinopyroxene-liquid geothermometer recommended for use in natural igneous systems with bulk SiO2 ≥ 70 wt%, which contain clinopyroxene with Mg# ≤ 65 and Al2O3 ≤ 7 wt%.


The new geothermometer lowers calculated temperatures by ~85 °C on average relative to Putirka (2008, Eq. 33) and reduces the uncertainty by a factor of two (standard error of estimate ±20 °C). When applied to natural systems, we find this new clinopyroxene-liquid geothermometer reconciles many inconsistencies between experimental phase equilibria and preexisting geothermometry results for silicic volcanism, including those from the Bishop Tuff and Yellowstone caldera-forming and post-caldera rhyolites. We also demonstrate that clinopyroxene is not restricted to near-liquidus temperatures in rhyolitic systems; clinopyroxene can be stable over a broad temperature range, often down to the solidus. An Excel spreadsheet and Python notebook for calculating temperature with this new geothermometer may be downloaded from GitHub at

  1. Funding

    This work was supported by the National Park Services research permit YELL-2015-SCI-6078 and by the U.S. National Science Foundation under Graduate Research Fellowship no. 026257-001 to K.K.B. and CAREER EAR-1654584 to C.B.T. The EPMA facilities at ASU are in part supported by the National Nanotechnology Coordinated Infrastructure grant ECCS-1542160. Thank you to Julia Hammer and David Neave whose reviews helped to improve this manuscript.


Special thanks to Tim Grove for the use of the experimental petrology lab at MIT, and to Wes Hildreth for sharing his unpublished probe data. Additional thanks to Axel Wittmann, Kayla Iacovino, Jessica Noviello, Crystylynda Fudge, and the EPIC group at ASU. Great appreciation to Keith Putirka whose thoughtful questions and insights have helped guide this research.

References cited

Almeev, R.R., Bolte, T., Nash, B.P., Holtz, F., Erdmann, M., and Cathey, H.E. (2012) High-temperature, low-H2O silicic magmas of the Yellowstone Hotspot: an experimental study of rhyolite from the Bruneau-Jarbidge Eruptive Center, Central Snake River Plain, USA. Journal of Petrology, 53, 1837–1866.Search in Google Scholar

Anderson, A.T., Davis, A.M., and Lu, F. (2000) Evolution of Bishop Tuff rhyolitic magma based on melt and magnetite inclusions and zoned phenocrysts. Journal of Petrology, 41, 449–473.Search in Google Scholar

Anderson, D.J., Lindsley, D.H., and Davidson, P.M. (1993) QUILF: A pascal program to assess equilibria among Fe, Mg, Mn, Ti oxides, pyroxenes, olivine, and quartz. Computers & Geosciences, 19, 1333–1350.Search in Google Scholar

Bartels, K.S., Kinzler, R. J., and Grove, T.L. (1991) High pressure phase relations of primitive high-alumina basalts from Medicine Lake volcano, northern California. Contributions to Mineralogy and Petrology, 108, 253–270.Search in Google Scholar

Befus, K.S., and Gardner, J.E. (2016) Magma storage and evolution of the most recent effusive and explosive eruptions from Yellowstone Caldera. Contributions to Mineralogy and Petrology, 171, 30.Search in Google Scholar

Befus, K.S., Bruyere, R.H., and Manga, M. (2018) Lava Creek Tuff Love. Presented at the Goldschmidt, Boston, U.S.A.Search in Google Scholar

Bindeman, I.N., and Valley, J.W. (2002) Oxygen isotope study of the Long Valley magma system, California: Isotope thermometry and convection in large silicic magma bodies. Contributions to Mineralogy and Petrology, 144, 185–205.Search in Google Scholar

Bindeman, I.N., Fu, B., Kita, N.T., and Valley, J.W. (2008) Origin and evolution of silicic magmatism at yellowstone based on ion microprobe analysis of isotopically zoned zircons. Journal of Petrology, 49, 163–193.Search in Google Scholar

Bolte, T., Holtz, F., Almeev, R., and Nash, B. (2015) The Blacktail Creek Tuff: an analytical and experimental study of rhyolites from the Heise volcanic field, Yellowstone hotspot system. Contributions to Mineralogy and Petrology, 169, 15.Search in Google Scholar

Cashman, K.V., and Giordano, G. (2014) Calderas and magma reservoirs. Journal of Volcanology and Geothermal Research, 288, 28–45.Search in Google Scholar

Chamberlain, K.J., Morgan, D.J., and Wilson, C.J.N. (2014) Timescales of mixing and mobilisation in the Bishop Tuff magma body: perspectives from diffusion chronometry. Contributions to Mineralogy and Petrology, 168, 1034.Search in Google Scholar

Christiansen, R.L. (2001) The Quaternary and Pliocene Yellowstone Plateau volcanic field of Wyoming, Idaho, and Montana, 145 p. U.S. Geological Survey, Reston, Virginia.Search in Google Scholar

Christiansen, R.L., Lowenstern, J.B., Smith, R.B., Heasler, H., Morgan, L.A., Nathenson, M., Mastin, L.G., Muffler, L.J.P., and Robinson, J.E. (2007) Preliminary Assessment of Volcanic and Hydrothermal Hazards in Yellowstone National Park and Vicinity, p. 94. U.S. Geological Survey.Search in Google Scholar

Elkins, L.T., and Grove, T.L. (1990) Ternary feldspar experiments and thermodynamic models. American Mineralogist, 75, 544–559.Search in Google Scholar

Elthon, D., and Scarfe, C.M. (1984) High-pressure phase equilibria of a high-magnesian basalt and the genesis of primary oceanic basalts. American Mineralogist, 69, 1–15.Search in Google Scholar

Feig, S.T., Koepke, J., and Snow, J.E. (2006) Effect of water on tholeiitic basalt phase equilibria: an experimental study under oxidizing conditions. Contributions to Mineralogy and Petrology, 152, 611–638.Search in Google Scholar

Feig, S.T., Koepke, J., and Snow, J.E. (2010) Effect of oxygen fugacity and water on phase equilibria of a hydrous tholeiitic basalt. Contributions to Mineralogy and Petrology, 160, 551–568.Search in Google Scholar

Frost, B.R., and Lindsley, D.H. (1992) Equilibria among Fe-Ti oxides, pyroxenes, olivine, and quartz: Part II. Application. American Mineralogist, 77, 1004–1020.Search in Google Scholar

Gardner, J.E., Befus, K.S., Gualda, G.A.R., and Ghiorso, M.S. (2014) Experimental constraints on rhyolite-MELTS and the Late Bishop Tuff magma body. Contributions to Mineralogy and Petrology, 168, 1051.Search in Google Scholar

Ghiorso, M.S., and Evans, B.W. (2008) Thermodynamics of rhombohedral oxide solid solutions and a revision of the Fe-Ti two-oxide geothermometer and oxygen-barometer. American Journal of Science, 308, 957–1039.Search in Google Scholar

Ghiorso, M.S., and Gualda, G.A.R. (2013) A method for estimating the activity of titania in magmatic liquids from the compositions of coexisting rhombohedral and cubic iron–titanium oxides. Contributions to Mineralogy and Petrology, 165, 73–81.Search in Google Scholar

Girard, G., and Stix, J. (2009) Magma recharge and crystal mush rejuvenation associated with early post-collapse Upper Basin Member Rhyolites, Yellowstone Caldera, Wyoming. Journal of Petrology, 50, 2095–2125.Search in Google Scholar

Girard, G., and Stix, J. (2010) Rapid extraction of discrete magma batches from a large differentiating magma chamber: the Central Plateau Member rhyolites, Yellowstone Caldera, Wyoming. Contributions to Mineralogy and Petrology, 160, 441–465.Search in Google Scholar

Grove, T.L., and Juster, T. C. (1989) Experimental investigations of low-Ca pyroxene stability and olivine-pyroxene-liquid equilibria at 1 -atm in natural basaltic and andesitic liquids. Contributions to Mineralogy and Petrology, 103, 287–305.Search in Google Scholar

Grove, T.L., Kinzler, R.J., and Bryan, W.B. (1992) Fractionation of mid-ocean ridge basalt (MORB). Geophysical Monograph, 71, 281–310.Search in Google Scholar

Gualda, G.A.R., and Ghiorso, M.S. (2013) The Bishop Tuff giant magma body: an alternative to the Standard Model. Contributions to Mineralogy and Petrology, 166, 755–775.Search in Google Scholar

Gualda, G.A.R., and Ghiorso, M.S. (2015) MELTS_Excel: A Microsoft Excel-based MELTS interface for research and teaching of magma properties and evolution. Geochemistry, Geophysics, Geosystems, 16, 315–324.Search in Google Scholar

Gualda, G.A.R., and Sutton, S.R. (2016) The year leading to a supereruption. PLOS One, 11, e0159200.Search in Google Scholar

Gualda, G.A.R., Ghiorso, M.S., Lemons, R.V., and Carley, T.L. (2012) Rhyolite-MELTS: a modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Journal of Petrology, 53, 875–890.Search in Google Scholar

Hervig, R.L., and Dunbar, N.W. (1992) Cause of chemical zoning in the Bishop (California) and Bandelier (New Mexico) magma chambers. Earth and Planetary Science Letters, 111, 97–108.Search in Google Scholar

Hildreth, E.W. (1977) The magma chamber of the Bishop Tuff: Gradients in temperature, pressure, and composition. Ph.D. thesis, University of California, Berkeley.Search in Google Scholar

Hildreth, W. (1981) Gradients in silicic magma chambers: Implications for lithospheric magmatism. Journal of Geophysical Research: Solid Earth, 86, 10153–10192.Search in Google Scholar

Hildreth, W., and Wilson, C.J.N. (2007) Compositional zoning of the Bishop Tuff. Journal of Petrology, 48, 951–999.Search in Google Scholar

Hildreth, W., Christiansen, R.L., and O’Neil, J.R. (1984) Catastrophic isotopic modification of rhyolitic magma at times of caldera subsidence, Yellowstone Plateau Volcanic Field. Journal of Geophysical Research: Solid Earth, 89, 8339–8369.Search in Google Scholar

Horn, S., and Schmincke, H.-U. (2000) Volatile emission during the eruption of Baitoushan Volcano (China/North Korea) ca. 969 AD. Bulletin of Volcanology, 61, 0537–0555.Search in Google Scholar

Huang, R., and Audétat, A. (2012) The titanium-in-quartz (TitaniQ) thermobarometer: A critical examination and re-calibration. Geochimica et Cosmochimica Acta, 84, 75–89.Search in Google Scholar

Huebner, J.S. (1980) Pyroxene phase equilibria at low pressure. Reviews in Mineralogy, 7, 213–288.Search in Google Scholar

Iacovino, K., Kim, J.S., Sisson, T.W., Lowenstern, J.B., Jang, J.N., Song, K.H., Ham, H.H., Ri, K.H., Donovan, A.R., Oppenheimer, C., and others. (2015) New Constraints on the Geochemistry of the Millennium Eruption of Mount Paektu (Changbaishan), Democratic People’s Republic of Korea/China. In 2015 AGU Fall Meeting. San Francisco, U.S.A.Search in Google Scholar

Iacovino, K., Kim, J.-S., Sisson, T., Lowenstern, J., Ri, K.-H., Jang, J.-N., Song, K.-H., Ham, S.-H., Oppenheimer, C., Hammond, J.O.S., and others. (2016) Quantifying gas emissions from the “Millennium Eruption” of Paektu volcano Democratic People’s Republic of Korea/China. Science Advances, 2, 1–11.Search in Google Scholar

Juster, T.C., Grove, T.L., and Perfit, M.R. (1989) Experimental constraints on the generation of FeTi basalts, andesites, and rhyodacites at the Galapagos Spreading Center, 85°W and 95 °W. Journal of Geophysical Research, 94, 9251.Search in Google Scholar

Kinzler, R.J., and Grove, T.L. (1992) Primary magmas of mid-ocean ridge basalts 1. Experiments and methods. Journal of Geophysical Research, 97, 6885.Search in Google Scholar

Liang, Y., Sun, C., and Yao, L. (2013) A REE-in-two-pyroxene thermometer for mafic and ultramafic rocks. Geochimica et Cosmochimica Acta, 102, 246–260.Search in Google Scholar

Lindsley, D.H. (1983) Pyroxene thermometry. American Mineralogist, 68, 477–493.Search in Google Scholar

Lindsley, D.H., and Andersen, D.J. (1983) A two-pyroxene thermometer. Journal of Geophysical Research, 88, A887.Search in Google Scholar

Lofgren, G.E., Huss, G.R., and Wasserburg, G.J. (2006) An experimental study of trace-element partitioning between Ti-Al-clinopyroxene and melt: Equilibrium and kinetic effects including sector zoning. American Mineralogist, 91, 1596–1606.Search in Google Scholar

Masotta, M., Mollo, S., Freda, C., Gaeta, M., and Moore, G. (2013) Clinopyroxene–liquid thermometers and barometers specific to alkaline differentiated magmas. Contributions to Mineralogy and Petrology, 166, 1545–1561.Search in Google Scholar

Matthews, N.E., Vazquez, J.A., and Calvert, A.T. (2015) Age of the Lava Creek supereruption and magma chamber assembly from combined 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals. Geochemistry, Geophysics, Geosystems, 16, 2508–2528, doi: 10.1002/2015GC005881.10.1002/2015GC005881Search in Google Scholar

Mollo, S., and Hammer, J.E. (2017) Dynamic crystallization in magmas. In W. Heinrich and R. Abart, Eds., Mineral Reaction Kinetics: Microstructures, Textures, Chemical and Isotopic Signatures, vol. 16, p. 378–418. Mineralogical Society of Great Britain & Ireland.Search in Google Scholar

Mollo, S., Del Gaudio, P., Ventura, G., Iezzi, G., and Scarlato, P. (2010) Dependence of clinopyroxene composition on cooling rate in basaltic magmas: Implications for thermobarometry. Lithos, 118, 302–312.Search in Google Scholar

Myers, M.L., Wallace, P.J., Wilson, C.J.N., Morter, B.K., and Swallow, E.J. (2016) Prolonged ascent and episodic venting of discrete magma batches at the onset of the Huckleberry Ridge supereruption, Yellowstone. Earth and Planetary Science Letters, 451, 285–297.Search in Google Scholar

Pamukcu, A.S., Gualda, G.A.R., and Anderson, A.T. (2012) Crystallization stages of the Bishop Tuff magma body recorded in crystal textures in pumice clasts. Journal of Petrology, 53, 589–609.Search in Google Scholar

Pamukcu, A.S., Ghiorso, M.S., and Gualda, G.A.R. (2016) High-Ti, bright-CL rims in volcanic quartz: a result of very rapid growth. Contributions to Mineralogy and Petrology, 171, 105.Search in Google Scholar

Putirka, K.D. (2008) Thermometers and barometers for volcanic systems. Reviews in Mineralogy and Geochemistry, 69, 61–120.Search in Google Scholar

Putirka, K.D., Mikaelian, H., Ryerson, F., and Shaw, H. (2003) New clinopyroxene-liquid thermobarometers for mafic, evolved, and volatile-bearing lava compositions, with applications to lavas from Tibet and the Snake River Plain, Idaho. American Mineralogist, 88, 1542–1554.Search in Google Scholar

Reid, M.R., Vazquez, J.A., and Schmitt, A.K. (2011) Zircon-scale insights into the history of a Supervolcano, Bishop Tuff, Long Valley, California, with implications for the Ti-in-zircon geothermometer. Contributions to Mineralogy and Petrology, 161, 293–311.Search in Google Scholar

Sack, R.O., and Ghiorso, M.S. (1994) Thermodynamics of multicomponent pyroxenes: II. Phase relations in the quadrilateral. Contributions to Mineralogy and Petrology, 116, 287–300.Search in Google Scholar

Salviulo, G., Secco, L., Marzoli, A., Piccirillo, E.M., and Nyobe, J.B. (2000) Ca-rich pyroxene from basic and silicic volcanic rocks from the Cameroon Volcanic Line (West-Africa): crystal chemistry and petrological relationships. Mineralogy and Petrology, 70, 73–88.Search in Google Scholar

Shaffer, J.S., and Till, C.B. (2016) New temperature and H2O estimates for Post Caldera Yellowstone Rhyolite Lavas using feldspar geothermometry and rhyolite-MELTS. In 2016 AGU Fall Meeting. San Francisco, U. S.A.Search in Google Scholar

Shamloo, H.I., and Till, C.B. (2019) Decadal transition from quiescence to supereruption: petrologic investigation of the Lava Creek Tuff, Yellowstone Caldera, WY. Contributions to Mineralogy and Petrology, 174, 32.Search in Google Scholar

Sisson, T.W. (1991) Pyroxene-high silica rhyolite trace element partition coefficients measured by ion microprobe. Geochimica et Cosmochimica Acta, 55, 1575–1585.Search in Google Scholar

Swallow, E.J., Wilson, C.J.N., Myers, M.L., Wallace, P.J., Collins, K.S., and Smith, E.G.C. (2018) Evacuation of multiple magma bodies and the onset of caldera collapse in a supereruption, captured in glass and mineral compositions. Contributions to Mineralogy and Petrology, 173, 33.Search in Google Scholar

Till, C.B., Vazquez, J.A., and Boyce, J.W. (2015) Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming. Geology, 43, 695–698.Search in Google Scholar

Vazquez, J.A., Kyriazis, S.F., Reid, M.R., Sehler, R.C., and Ramos, F.C. (2009) Thermochemical evolution of young rhyolites at Yellowstone: Evidence for a cooling but periodically replenished postcaldera magma reservoir. Journal of Volcanology and Geothermal Research, 188, 186–196.Search in Google Scholar

Wark, D.A., and Watson, E.B. (2006) TitaniQ: a titanium-in-quartz geothermometer. Contributions to Mineralogy and Petrology, 152, 743–754.Search in Google Scholar

Wark, D.A., Hildreth, W., Watson, E.B., and Cherniak, D.J. (2004) Origin of thermal and compositional zoning in the Bishop Magma Reservoir: Insights from zoned quartz phenocrysts p. 3. Presented at the 2004 AGU Fall Meeting, San Francisco, California, U.S.A.Search in Google Scholar

Wark, D.A., Hildreth, W., Spear, F.S., Cherniak, D. J., and Watson, E.B. (2007) Pre-eruption recharge of the Bishop magma system. Geology, 35, 235.Search in Google Scholar

Warshaw, C.M., and Smith, R.L. (1988) Pyroxenes and fayalites in the Bandelier Tuff, New Mexico: temperatures and comparison with other rhyolites. American Mineralogist, 73, 1025–1037.Search in Google Scholar

Wilcock, J., Goff, F., Minarik, W.G., and Stix, J. (2013) Magmatic recharge during the formation and resurgence of the Valles Caldera, New Mexico, USA: Evidence from quartz compositional zoning and geothermometry. Journal of Petrology, 54, 635–664.Search in Google Scholar

Wilson, C.J.N., and Hildreth, W. (1997) The Bishop Tuff: New insights from eruptive stratigraphy. The Journal of Geology, 105, 407–440.Search in Google Scholar

Zhang, Y. (2008) Geochemical Kinetics, 631 p. Princeton University Press, New Jersey.Search in Google Scholar

Received: 2018-10-08
Accepted: 2019-03-28
Published Online: 2019-06-20
Published in Print: 2019-07-26

© 2019 Walter de Gruyter GmbH, Berlin/Boston