Jump to ContentJump to Main Navigation
Show Summary Details
More options …

American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian

IMPACT FACTOR 2017: 2.645

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

See all formats and pricing
More options …
Volume 102, Issue 1


Experimental investigation into the substitution mechanisms and solubility of Ti in garnet

Michael R. Ackerson
  • Corresponding author
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
  • Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, United States of America
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ E. Bruce Watson
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Nicholas D. Tailby
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Frank S. Spear
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2017-01-03 | DOI: https://doi.org/10.2138/am-2017-5632


Garnet is a common and important mineral in metamorphic systems, but the mechanisms by which it incorporates Ti—one of the major elements in the crust—are not well constrained. This study draws upon garnets synthesized at a range of temperatures and pressures to understand Ti solubility and the substitution mechanisms that govern its incorporation into garnet at eclogite and granulite facies conditions. Garnets from these synthesis experiments can incorporate up to several wt% TiO2. Comparison of Ti content with deficits in Al and Si in garnet indicates that Ti is incorporated by at least two substitution mechanisms (VITi4+ + VIM2+ ↔ 2VIAl3+, and VITi4+ + IVAl3+VIAl3+ + IVSi4+). Increasing Ti solubility is correlated with increasing Ca and Fe/Mg ratios in garnet, clinopyroxene and melt. The complexity of the substitution mechanisms involved in Ti solubility in garnet makes practical Ti-in- garnet thermobarometry infeasible at present. However, a model fit to Ti partitioning between garnet and melt can be used to predict melt compositions in high-grade metamorphic systems. Additionally, the solubility and substitution mechanisms described here can help explain the presence of crystallographically aligned rutile needles in high-grade metamorphic systems.

Keywords: Garnet; titanium; UHP; UHT; experimental petrology

References cited

  • Ague, J.J., and Eckert, J.O. (2012) Precipitation of rutile and ilmenite needles in garnet: Implications for extreme metamorphic conditions in the Acadian Orogen, U.S.A. American Mineralogist, 97, 840–855.Google Scholar

  • Ague, J.J., Eckert, J.O., Chu, X., Baxter, E.F., and Chamberlain, C.P. (2013) Discovery of ultrahigh-temperature metamorphism in the Acadian Orogen, Connecticut, U.S.A. Geology, 41, 271–274.Google Scholar

  • Alifirova, T.A., Pokhilenko, L.N., Ovchinnikov, Y.I., Donnelly, C.L., Riches, A.J.V., and Taylor, L.A. (2012) Petrologic origin of exsolution textures in mantle minerals: Evidence in pyroxenitic xenoliths from Yakutia kimberlites. International Geology Review, 54, 1071–1092.Google Scholar

  • Armbruster, T., and Geiger, C. (1993) Andradite crystal chemistry, dynamic X-site disorder and structural strain in silicate garnets. European Journal of Mineralogy, 5, 59–72.Google Scholar

  • Auzanneau, E., Schmidt, M.W., Vielzeuf, D., and Connolly, J.A.D. (2009) Titanium in phengite: a geobarometer for high temperature eclogites. Contributions to Mineralogy and Petrology, 159, 1–24.Google Scholar

  • Axler, J.A., and Ague, J.J. (2015) Exsolution of rutile or apatite precipitates surrounding ruptured inclusions in garnet from UHT and UHP rocks. Journal of Metamorphic Geology, 33, 829–848.Google Scholar

  • Bastin, G.F., van Loo, F.J.J., Vosters, P.J.C., and Vrolijk, J.W.G.A. (1984) An iterative procedure for the correction of secondary fluorescence effects in electron-probe microanalysis near phase boundaries. Spectrochimica Acta, 39B, 1517–1522.Google Scholar

  • Baxter, E.F., Ague, J.J., and Depaolo, D.J. (2002) Prograde temperature–time evolution in the Barrovian type–locality constrained by Sm/Nd garnet ages from Glen Clova, Scotland. Journal of the Geological Society, 159, 71–82.Google Scholar

  • Blundy, J., and Wood, B. (1994) Prediction of crystal–melt partition coefficients from elastic moduli. Nature, 372, 452–454.Google Scholar

  • Boehnke, P., Watson, E.B., Trail, D., Harrison, T.M., and Schmitt, A.K. (2013) Zircon saturation re-revisited. Chemical Geology, 351, 324–334.Google Scholar

  • Boffa Ballaran, T., Carpenter, M.A., Geiger, C.A., and Koziol, A.M. (1999) Local structural heterogeneity in garnet solid solutions. Physics and Chemistry of Minerals, 26, 554–569.Google Scholar

  • Bosenick, A., Dove, M.T., and Geiger, C.A. (2000) Simulation studies on the pyrope-grossular garnet solid solution. Physics and Chemistry of Minerals, 27, 398–418.Google Scholar

  • Chakhmouradian, A.R., and McCammon, C.A. (2005) Schorlomite: A discussion of the crystal chemistry, formula, and inter-species boundaries. Physics and Chemistry of Minerals, 32, 277–289.Google Scholar

  • Chambers, J.A., and Kohn, M.J. (2012) Titanium in muscovite, biotite, and hornblende: Modeling, thermometry, and rutile activities of metapelites and amphibolites. American Mineralogist, 97, 543–555.Google Scholar

  • Cherniak, D.J., Watson, E.B., and Wark, D.A. (2007) Ti diffusion in quartz. Chemical Geology, 236, 65–74.Google Scholar

  • Dickinson, J.E. Jr., and Hess, P.C. (1985) Rutile solubility and titanium coordination in silicate melts. Geochimica et Cosmochimica Acta, 49, 2289–2296.Google Scholar

  • Ellis, D.J., and Green, D.H. (1979) An experimental study of the effect of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria. Contributions to Mineralogy and Petrology, 71, 13–22.Google Scholar

  • Feenstra, A., and Engi, M. (1998) An experimental study of the Mg-Fe exchange between garnet and ilmenite. Contributions to Mineralogy and Petrology, 131, 379–392.Google Scholar

  • Fournelle, J. (2007) Problems in trace element EPMA: Modeling secondary fluorescence with PENEPMA. AGU Fall Meeting Abstracts, 51, 0329.Google Scholar

  • (2007) The problem of secondary fluorescence in EPMA in the application of the Ti-in-zircon geothermometer and the utility of PENEPMA Monte Carlo Program. Microscopy and Microanalysis, 13, 1390–1391.Google Scholar

  • Grew, E.S., Marsh, J.H., Yates, M.G., Lazic, B., Armbruster, T., Locock, A., Bell, S.W., Dyar, M.D., Bernhardt, H.-J., and Medenbach, O. (2010) Menzerite-(Y), a new species, {(Y,REE)(Ca,Fe2+)2}[(Mg,Fe2+)(Fe3+,Al)](Si3)O12, from a felsin granulite, Parry Sound, Ontario, and a new garnet end-member, {Y2Ca}[Mg2] (Si3)O12. Canadian Mineralogist, 48, 1171–1193.Google Scholar

  • Grew, E.S., Locock, A.J., Mills, S.J., Galuskina, I.O., Galuskin, E.V., and Halenius, U. (2013) Nomenclature of the garnet supergroup. American Mineralogist, 98, 785–811.Google Scholar

  • Gwalani, L.G., Rock, N.M.S., Ramasamy, R., Griffin, B.J., and Mulai, B.P. (2000) Complexe;y zoned Ti-rich melanite-schorlomite garnets from Ambadungar carbonatite-alkalic complex, Deccan Igneous Province, Gujarat State, Western India. Journal of Asian Earth Sciences, 18, 163–176.Google Scholar

  • Harley, S.L. (1984) An experimental study of the partitioning of Fe and Mg between garnet and orthopyroxene. Contributions to Mineralogy and Petrology, 86, 359–373.Google Scholar

  • Hayden, L.A., and Watson, E.B. (2007) Rutile saturation in hydrous siliceous melts and its bearing on Ti-thermometry of quartz and zircon. Earth and Planetary Science Letters, 258, 561–568.Google Scholar

  • Hazen, R., Downs, R., Finger, L., and Conrad, P. (1994) Crystal chemistry of Ca- bearing majorite. American Mineralogist, 79, 581–584.Google Scholar

  • Henmi, C., Kusachi, I., and Henmi, K. (1995) Morimotoite, Ca3TiFe2+SiO12, a new titanian garnet form Fuka, Okayama Prefecture, Japan. Mineralogical Magazine, 59, 115–120.Google Scholar

  • Henry, D.J., Guidotti, C.V., and Thompson, J.A. (2005) The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms. American Mineralogist, 90, 316–328.Google Scholar

  • Huggins, F.E., Virgo, D., and Huckenholz, H.G. (1977) Titanium-containig silicate garnets. II. The crystal chemistry of melanites and schorlomites. American Mineralogist, 62, 646–665.Google Scholar

  • Hwang, S.L., Yui, T.F., Chu, H.T., Shen, P., Schertl, H.P., Zhang, R.Y., and Liou, J.G. (2007) On the origin of oriented rutile needles in garnet from UHP eclogites. Journal of Metamorphic Geology, 25, 349–362.Google Scholar

  • Jercinovic, M.J., Williams, M.L., and Lane, E.D. (2008) In-situ trace element analysis of monazite and other fine-grained accessory minerals by EPMA. Chemical Geology, 254, 197–215.Google Scholar

  • Kohn, M.J., and Spear, F.S. (1991a) Error propagation for barometers; 1, Accuracy and precision of experimentally located end-member reactions. American Mineralogist, 76, 128–137.Google Scholar

  • (1991b) Error propagation for barometers; 2, Application to rocks. American Mineralogist, 76, 138–147.Google Scholar

  • Koziol, A.M., and Bohlen, S.R. (1992) Solution properties of almandine-pyrope garnet as determined by phase equilibrium experiments. American Mineralogist, 77, 765–773.Google Scholar

  • Krawczynski, M.J., Sutton, S.R., Grove, T.L., Newville, M. (2009) Titanium oxidation state and coordination in the lunar high-titanium glass source mantle. Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois (U.S.A.).Google Scholar

  • Krenn, K., Bauer, C., Proyer, A., Mposkos, E., and Hoinkes, G. (2008) Fluid entrapment and reequilibration during subduction and exhumation: A case study from the high-grade Nestos shear zone, Central Rhodope, Greece. Lithos, 104, 33–53.Google Scholar

  • Krogh, E.J. (1988) The garnet-clinopyroxene Fe-Mg geothermometer—A rein-terpretation of existing experimental data. Contributions to Mineralogy and Petrology, 99, 44–48.Google Scholar

  • Kuhberger, A., Fehr, T., Huckenholz, H.G., and Amthauer, G. (1989) Crystal chemistry of a natural schorlomite and Ti-andradites synthesized at different oxygen fugacitites. Physics and Chemistry of Minerals, 16, 734–740.Google Scholar

  • Lanzirotti, A. (1995) Yttrium zoning in metamorphic garnets. Geochimica et Cosmochimica Acta, 59, 4105–4110.Google Scholar

  • Locock, A.J. (2008) An Excel spreadsheet to recast analyses of garnet into end-member components, and a synopsis of the crystal chemistry of natural silicate garnets. Computers & Geosciences, 34, 1769–1780.Google Scholar

  • Mahood, G., and Hildreth, W. (1983) Large partition coefficients for trace elements in high-silica rhyolites. Geochimica et Cosmochimica Acta, 47, 11–30.Google Scholar

  • Nakamura, D. (2009) A new formulation of garnet–clinopyroxene geothermometer based on accumulation and statistical analysis of a large experimental data set. Journal of Metamorphic Geology, 27, 495–508.Google Scholar

  • Novak, G.A., and Gibbs, G.V. (1971) The crystal chemistry of the silicate garnets. American Mineralogist, 56, 791–825.Google Scholar

  • Pattison, D.R.M., and Newton, R.C. (1989) Reversed experimental calibration of the garnet–clinopyroxene Fe-Mg exchange thermometer. Contributions to Mineralogy and Petrology, 101, 87–103.Google Scholar

  • Plank, T., and Langmuir, C.H. (1998) The chemical composition of subducting sediment and its consequences for the crust and mantle. Chemical Geology, 145, 325–394.Google Scholar

  • Proyer, A., Habler, G., Abart, R., Wirth, R., Krenn, K., and Hoinkes, G. (2013) TiO2 exsolution from garnet by open-system precipitation: evidence from crystallographic and shape preferred orientation of rutile inclusions. Contributions to Mineralogy and Petrology, 166, 211–234.Google Scholar

  • Pyle, J.M., and Spear, F.S. (2003) Four generations of accessory-phase growth in low-pressure migmatites from SW New Hampshire. American Mineralogist, 88, 338–351.Google Scholar

  • Qian, Q., and Hermann, J. (2013) Partial melting of lower crust at 10–15 kbar: Constraints on adakite and TTG formation. Contributions to Mineralogy and Petrology, 165, 1195–1224.Google Scholar

  • Råheim, A., and Green, D.H. (1974) Experimental determination of the temperature and pressure dependence of the Fe-Mg partition coefficient for coexisting garnet and clinopyroxene. Contributions to Mineralogy and Petrology, 48, 179–203.Google Scholar

  • Rapp, R.P., and Watson, E.B. (1995) Dehydration melting of metabasalt at 8–32 kbar: Implications for continental growth and crust-mantle recycling. Journal of Petrology, 36, 891–931.Google Scholar

  • Ravna, K. (2000) The garnet–clinopyroxene Fe2+–Mg geothermometer: An updated calibration. Journal of Metamorphic Geology, 18, 211–219.Google Scholar

  • Richter, F.M., Davis, A.M., DePaolo, D.J., and Watson, E.B. (2003) Isotope fractionation by chemical diffusion between molten basalt and rhyolite. Geochimica et Cosmochimica Acta, 67, 3905–3923.Google Scholar

  • Ryerson, F.J., and Hess, P.C. (1978) Implications of liquid-liquid distribution coefficients to mineral-liquid partitioning. Geochimica et Cosmochimica Acta, 42, 921–932.Google Scholar

  • Ryerson, F.J., and Watson, E.B. (1987) Rutile saturation in magmas: implications for TiNbTa depletion in island-arc basalts. Earth and Planetary Science Letters, 86, 225–239.Google Scholar

  • Schertl, H.-P., Schreyer, W., and Chopin, C. (1991) The pyrope-coesite rocks and their country rocks at Parigi, Dora Maira Massif, Western Alps: Detailed petrography, mineral chemistry and PT-path. Contributions to Mineralogy and Petrology, 108, 1–21.Google Scholar

  • Sclater, J.G., Jaupart, C., and Galson, D. (1980) The heat flow through oceanic and continental crust and the heat loss of the Earth. Reviews of Geophysics, 18, 269–311.Google Scholar

  • Scordari, F., Schingaro, E., Malitesta, C., and Pedrazzi, G. (2003) Crystal chemistry of Ti-bearing garnets with volcanic origin p. 5605. Presented at the EGS-AGU-EUG Joint Assembly.Google Scholar

  • Spear, F.S. (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths, 799 p. Mineralogical Society of America.Google Scholar

  • Tailby, N.D. (2009) New experimental techniques for studying: (i) trace element substitution in minerals, and (ii) determining S-L-V relationships in silicate- H2O systems at high pressure. Australian National University.Google Scholar

  • Taylor, J., Nicoli, G., Stevens, G., Frei, D., and Moyen, J.-F. (2014) The processes that control leucosome compositions in metasedimentary granulites: perspectives from the Southern Marginal Zone migmatites, Limpopo Belt, South Africa. Journal of Metamorphic Geology, 32, 713–742.Google Scholar

  • Thöni, M. (2002) Sm–Nd isotope systematics in garnet from different lithologies (Eastern Alps): Age results, and an evaluation of potential problems for garnet Sm-Nd chronometry. Chemical Geology, 185, 255–281.Google Scholar

  • Ungaretti, L., Leona, M., Merli, M., and Oberti, R. (1995) Non-ideal solid-solution in garnet: crystal-structure evidence and modelling. European Journal of Mineralogy, 7, 1299–1312.Google Scholar

  • Van Roermund, H.L.M., Drury, M.R., Barnhoorn, A., and De Ronde, A. (2000) Non-silicate inclusions in garnet from an ultra-deep orogenic peridotite. Geological Journal, 35, 209–229.Google Scholar

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

  • Watson, E.B. (1976) Two-liquid partition coefficients: Experimental data and geochemical implications. Contributions to Mineralogy and Petrology, 56, 119–134.Google Scholar

  • Watson, E.B., and Harrison, T.M. (1983) Zircon saturation revisited: Temperature and composition effects in various crustal magma types. Earth and Planetary Science Letters, 64, 295–304.Google Scholar

  • Waychunas, G.A. (1987) Synchrotron radiation XANES spectroscopy of Ti in minerals: Effects of Ti bonding distances, Ti valence, and site geometry on absorption edge structure. American Mineralogist, 72, 89–101.Google Scholar

  • Wentorf, R.H. (1956) The formation of Gore Mountain [New York] garnet and hornblende at high temperature and pressure. American Journal of Science, 254, 413–419.Google Scholar

  • Whitney, D.L., and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187.Google Scholar

  • Ye, K., Cong, B., and Ye, D. (2000) The possible subduction of continental material to depths greater than 200 km. Nature, 407, 734–736.Google Scholar

  • Yoder, H.S., and Tilley, C.E. (1962) Origin of basalt magmas: An experimental study of natural and synthetic rock systems. Journal of Petrology, 3, 342–532.Google Scholar

  • Zedlitz, O. (1933) Über titanreichen Kalkeisengranat I. Centralblatt für Mineralogie, Geologie und Paläontologie, Abt. A, 225–239.Google Scholar

  • Zen, E.-A. (1986) Aluminum enrichment in silicate melts by fractional crystallization: Some mineralogic and petrographic constraints. Journal of Petrology, 27, 1095–1117.Google Scholar

  • Zhang, R.Y., Zhai, S.M., Fei, Y.W., and Liou, J.G. (2003) Titanium solubility in coexisting garnet and clinopyroxene at very high pressure: The significance of exsolved rutile in garnet. Earth and Planetary Science Letters, 216, 591–601.Google Scholar

  • Zhang, R.Y., Liou, J.G., Zheng, J.-P., Griffin, W.L., Yui, T.-F., and O’Reilly, S.Y. (2005) Petrogenesis of the Yangkou layered garnet-peridotite complex, Sulu UHP terrane, China. American Mineralogist, 90, 801–813.Google Scholar

About the article

Received: 2015-11-19

Accepted: 2016-07-25

Published Online: 2017-01-03

Published in Print: 2017-01-01

Citation Information: American Mineralogist, Volume 102, Issue 1, Pages 158–172, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2017-5632.

Export Citation

© 2017 by Walter de Gruyter Berlin/Boston.

Comments (0)

Please log in or register to comment.
Log in