Ti site occupancy in zircon

被引:69
作者
Tailby, N. D. [1 ,2 ]
Walker, A. M. [3 ]
Berry, A. J. [4 ]
Hermann, J. [2 ]
Evans, K. A. [5 ]
Mavrogenes, J. A. [2 ]
O'Neill, H. St C. [2 ]
Rodina, I. S. [6 ]
Soldatov, A. V. [6 ]
Rubatto, D. [2 ]
Sutton, S. R. [7 ,8 ]
机构
[1] Rensselaer Polytech Inst, Dept Earth & Environm Sci, Troy, NY 12180 USA
[2] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200, Australia
[3] Univ Bristol, Dept Earth Sci, Bristol BS8 1RJ, Avon, England
[4] Univ London Imperial Coll Sci Technol & Med, Dept Earth Sci & Engn, London SW7 2AZ, England
[5] Curtin Univ Technol, Dept Appl Geol, Bentley, WA 6845, Australia
[6] So Fed Univ, Ctr Nanoscale Struct Matter, Rostov Na Donu 344090, Russia
[7] Univ Chicago, CARS, Chicago, IL 60637 USA
[8] Univ Chicago, Dept Geophys Sci, Chicago, IL 60637 USA
基金
美国国家科学基金会;
关键词
RARE-EARTH-ELEMENTS; SILICATE-GLASSES; IN-ZIRCON; COORDINATION CHEMISTRY; XANES SPECTROSCOPY; CONTINENTAL-CRUST; SOLID-SOLUTION; CATHODOLUMINESCENCE; TITANIUM; RUTILE;
D O I
10.1016/j.gca.2010.11.004
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Ti site occupancy in zircon (ZrSiO4) is fundamental to thermobarometry because substitution mechanisms control Ti content temperature relations. Here we describe the results of three independent methods used to demonstrate that Ti substitutes for Si and not Zr in zircon. Zircon grains were synthesized from oxide powders held in a Na2WO4 flux at 1 bar and 1300 degrees C. Zircon grains equilibrated with rutile + cristobalite show Ti contents (1201 ppm) nearly half that of zircon grains equilibrated with srilankite ((Ti,Zr)O-2) + tetragonal zirconia (2640 ppm). The lower Ti content of zircon grains produced at silica-saturated conditions indicates that Ti substitution predominately occurs on the Si site. Moreover, the higher Ti contents of silica-saturated experiments at I bar (1201 ppm), relative to those at 1 GPa (457 ppm, Ferry and Watson, 2007), indicates a substantial pressure effect on Ti solubility in zircon. Measured Ti K-alpha edge X-ray Absorption Near Edge Structure (XANES) spectra of synthetic zircon grains show energies and normalized intensities akin to those seen among tetrahedrally coordinated Ti-bearing standard minerals, strongly suggesting that Ti occupies the Si site. Density functional theory (DFT) calculations confirm that Ti substitution is most likely to occur on the Si site and predict a Ti-O bond length of 1.797 angstrom (compared to an average of 2.160 angstrom for substitution on the Zr site), in excellent agreement with X-ray Absorption Fine Structure (EXAFS) spectra of experimentally grown zircon grains which indicate a value of 1.76(1) angstrom. The software FEFF 8.4 was used to simulate XANES spectra from the defect structures determined by DFT for Ti substituting on both the Si and Zr sites. The predicted spectrum for Ti on the Si site reproduces all the key features of the experimental zircon spectra, whereas Ti on the Zr site is markedly different. All applied methods confirm that Ti substitutes for Si in zircon. Consequently, the Ti content of zircon at a given pressure is not only a function of temperature, but will increase with decreasing silica activity. Because elements that activate or quench cathodoluminescence (CL) in zircon are incorporated into the Zr site, a decoupling of CL from Ti contents incorporated on the Si site in zircon is expected. This hypothesis has been verified by a systematic CL-trace element study of natural and experimental zircon. (C) 2010 Elsevier Ltd. All rights reserved.
引用
收藏
页码:905 / 921
页数:17
相关论文
共 59 条
  • [1] Early-middle Archaean crustal evolution deduced from Lu-Hf and U-Pb isotopic studies of single zircon grains
    Amelin, Y
    Lee, DC
    Halliday, AN
    [J]. GEOCHIMICA ET COSMOCHIMICA ACTA, 2000, 64 (24) : 4205 - 4225
  • [2] CRYSTALLIZATION AND SOLUBILITY OF ZIRCON AND PHENACITE IN CERTAIN MOLTEN SALTS
    BALLMAN, AA
    LAUDISE, RA
    [J]. JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 1965, 48 (03) : 130 - &
  • [3] Titanium substitution mechanisms in forsterite
    Berry, Andrew J.
    Walker, Andrew M.
    Hermann, Jorg
    O'Neill, Hugh St. C.
    Foran, Garry J.
    Gale, Julian D.
    [J]. CHEMICAL GEOLOGY, 2007, 242 (1-2) : 176 - 186
  • [4] CARUBA R, 1974, B SOC FR MINERAL CR, V97, P278
  • [5] Ti diffusion in zircon
    Cherniak, D. J.
    Watson, E. B.
    [J]. CHEMICAL GEOLOGY, 2007, 242 (3-4) : 473 - 483
  • [6] Atlas of zircon textures
    Corfu, F
    Hanchar, JM
    Hoskin, PWO
    Kinny, P
    [J]. ZIRCON, 2003, 53 : 469 - 500
  • [7] Degeling H.S., 2003, THESIS AUSTR NATL U
  • [8] ABINITIO CURVED-WAVE X-RAY-ABSORPTION FINE-STRUCTURE
    DELEON, JM
    REHR, JJ
    ZABINSKY, SI
    ALBERS, RC
    [J]. PHYSICAL REVIEW B, 1991, 44 (09) : 4146 - 4156
  • [9] Deposition and element fractionation processes during atmospheric pressure laser sampling for analysis by ICP-MS
    Eggins, SM
    Kinsley, LPJ
    Shelley, JMG
    [J]. APPLIED SURFACE SCIENCE, 1998, 127 : 278 - 286
  • [10] Compositional heterogeneity in NIST SRM 610-617 glasses
    Eggins, SM
    Shelley, JMG
    [J]. GEOSTANDARDS NEWSLETTER-THE JOURNAL OF GEOSTANDARDS AND GEOANALYSIS, 2002, 26 (03): : 269 - 286