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American Mineralogist

Journal of Earth and Planetary Materials

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


IMPACT FACTOR 2017: 2.645

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1945-3027
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Volume 102, Issue 1

Issues

XAFS spectroscopic study of Ti coordination 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
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/ Nicholas D. Tailby
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
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/ E. Bruce Watson
  • Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States of America
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Published Online: 2017-01-03 | DOI: https://doi.org/10.2138/am-2017-5633

Abstract

Titanium can be incorporated either tetrahedrally (IVTi) or octahedrally (VITi) in most silicate minerals. Ti K-edge X-ray absorption fine structure (XAFS) spectroscopy enables observation of Ti coordination in minerals and melts. In this study, XAFS is used to determine the coordination of Ti in synthetic and natural garnets. Garnets grown synthetically at eclogite- and granulite-facies conditions can contain several wt% TiO2, most of which is incorporated as VITi. This observation aligns with major element trends in these garnets. In natural garnets grown at lower temperatures and pressures, on the other hand, Ti is observed to occupy both the octahedral and tetrahedral sites in garnet—in some cases Ti is almost entirely fourfold coordinated. Combined with previous research (see Ackerson et al. 2017, this issue) on substitution mechanisms for VITi, the results of this study demonstrate that Ti is incorporated on two crystallographic sites in garnet by at least three primary substitution mechanisms. In both natural and synthetic garnets, there is a discernible increase in VITi content in garnet with increasing temperature and pressure, suggesting a significant role for these two parameters in determining Ti solubility. However, a continuous increase in VITi with increasing grossular content also suggests that the Ca content of the garnet plays a critical role.

Keywords: Garnet; Ti substitution; XANES; XAFS

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, USA. Geology, 41, 271–274.Google Scholar

  • Antao, S.M. (2014) Schorlomite and morimotoite: what’s in a name? Powder Diffraction, 29, 346–351.Google Scholar

  • Bishop, F.C., Smith, J.V., and Dawson, J.B. (1978) Na, K, P and Ti in garnet, pyroxene and olivine from peridotite and eclogite xenoliths from African kimberlites. Lithos, 11, 155–173.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

  • Cottrell, E., Kelley, K.A., Lanzirotti, A., and Fischer, R.A. (2009) High-precision determination of iron oxidation state in silicate glasses using XANES. Chemical Geology, 268, 167–179.Google Scholar

  • Daniel, C.G., and Spear, F.S. (1998) Three-dimensional patterns of garnet nucleation and growth. Geology, 26, 503.Google Scholar

  • Ene, V.V., and Schulze, D.J. (2013) Major and trace element geochemistry of ilmenite suites from the Kimberley diamond mines, South Africa. AGU Fall Meeting Abstracts, 23, 2765.Google Scholar

  • Farges, F. (1997) Coordination of Ti4+ in silicate glasses: A high-resolution XANES spectroscopy study at the Ti K edge. American Mineralogist, 82, 36–43.Google Scholar

  • Farges, F., Brown, G.E. Jr., Navrotsky, A., Gan, H., and Rehr, J.J. (1996a) Coordination chemistry of Ti(IV) in silicate glasses and melts: II. Glasses at ambient temperature and pressure. Geochimica et Cosmochimica Acta, 60, 3039–3053.Google Scholar

  • Farges, F., Brown, G.E. Jr., and Rehr, J.J. (1996b) Coordination chemistry of Ti(IV) in silicate glasses and melts: I. XAFS study of titanium coordination in oxide model compounds. Geochimica et Cosmochimica Acta, 60, 3023–3038.Google Scholar

  • Farges, F, Brown, G.E., and Rehr, J.J. (1997) Ti K-edge XANES studies of Ti coordination and disorder in oxide compounds: Comparison between theory and experiment. Physical Review B, 56, 1809–1819.Google Scholar

  • Ferry, J.M., and Watson, E.B. (2007) New thermodynamic models and revised calibrations for the Ti-in-zircon and Zr-in-rutile thermometers. Contributions to Mineralogy and Petrology, 154, 429–437.Google Scholar

  • Flohr, M.J.K., and Ross, M. (1990) Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites. Lithos, 26, 67–98.Google Scholar

  • Hallett, B.W., and Spear, F.S. (2011) Insight into the cooling history of the Valhalla complex, British Columbia. Lithos, 125, 809–824.Google Scholar

  • Hirsch, D.M., Prior, D.J., and Carlson, W.D. (2003) An overgrowth model to explain multiple, dispersed high-Mn regions in the cores of garnet porphyroblasts. American Mineralogist, 88, 131–141.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

  • Mposkos, E.D., and Kostopoulos, D.K. (2001) Diamond, former coesite and supersilicic garnet in metasedimentary rocks from the Greek Rhodope: a new ultrahigh-pressure metamorphic province established. Earth and Planetary Science Letters, 192, 497–506.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 Tinkham, D.K. (2009) Interplay between equilibrium and kinetics in prograde metamorphism of pelites: an example from the Nelson aureole, British Columbia. Journal of Metamorphic Geology, 27, 249–279.Google Scholar

  • Pattison, D.R.M., and Vogl, J.J. (2005) Contrasting Sequences of Metapelitic Mineral-Assemblages in the aureole of the Tilted Nelson Batholith, British Columbia: Implications for phase equilibria and pressure determination in andalusite-sillimanite-type settings. Canadian Mineralogist, 43, 51–88.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

  • Ravel, B., and Newville, M. (2005) ATHENA, ARTEMIS, HEPHAESTUS: Data analysis for X-ray absorption spectroscopy using IFEFFIT. Journal of Synchrotron Radiation, 12, 537–541.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

  • Snoeyenbos, D.R., Williams, M.L., and Hanmer, S. (1995) Archean high-pressure metamorphism in the western Canadian Shield. European Journal of Mineralogy, 7, 1251–1272.Google Scholar

  • Spear, F.S. (2004) Fast cooling and exhumation of the Valhalla Metamorphic Core Complex, Southeastern British Columbia. International Geology Review, 46, 193–209.Google Scholar

  • Spear, F.S., and Daniel, C.G. (2001) Diffusion control of garnet growth, Harpswell Neck, Maine, USA. Journal of Metamorphic Geology, 19, 179–195.Google Scholar

  • Spear, F.S., and Parrish, R.R. (1996) Petrology and cooling rates of the Valhalla Complex, British Columbia, Canada. Journal of Petrology, 37, 733–765.Google Scholar

  • Spear, F.S., Hickmott, D.D., and Selverstone, J. (1990) Metamorphic consequences of thrust emplacement, Fall Mountain, New Hampshire. Geological Society of America Bulletin, 102, 1344–1360.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

  • Thomas, J.B., Watson, E.B., Spear, F.S., Shemella, P.T., Nayak, S.K., and Lanzirotti, A. (2010) TitaniQ under pressure: the effect of pressure and temperature on the solubility of Ti in quartz. Contributions to Mineralogy and Petrology, 160, 743–759.Google Scholar

  • Trail, D., Watson, E.B., and Tailby, N.D. (2012) Ce and Eu anomalies in zircon as proxies for the oxidation state of magmas. Geochimica et Cosmochimica Acta, 97, 70–87.Google Scholar

  • Tropper, P., Konzett, J., and Finger, F. (2005) Experimental constraints on the formation of high-P/high-T granulites in the Southern Bohemian Massif. European Journal of Mineralogy, 17, 343–356.Google Scholar

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

  • Watson, E.B., and Harrison, T.M. (2005) Zircon thermometer reveals minimum melting conditions on earliest Earth. Science, 308, 841–844.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

  • 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 173–183, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2017-5633.

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© 2017 by Walter de Gruyter Berlin/Boston.

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