TY - JOUR
T1 - Diffusion anisotropy of Ti in zircon and implications for Ti-in-zircon thermometry
AU - Bloch, E. M.
AU - Jollands, M. C.
AU - Tollan, P.
AU - Plane, F.
AU - Bouvier, A. S.
AU - Hervig, R.
AU - Berry, A. J.
AU - Zaubitzer, C.
AU - Escrig, S.
AU - Müntener, O.
AU - Ibañez-Mejia, M.
AU - Alleon, J.
AU - Meibom, A.
AU - Baumgartner, L. P.
AU - Marin-Carbonne, J.
AU - Newville, M.
N1 - Funding Information:
We thank James Watkins, Tanya Ewing, Sumit Chakraborty, Daniela Rubatto, Jörg Hermann and Peter Reiners for constructive discussions throughout the course of this study, as well as Thierry Adatte, Bi Wen Hua and Arnaud Magrez for assistance with powder and single-crystal XRD measurements. We are grateful for a review by Aitor Cambeses and editorial handling by Rajdeep Dasgupta. This research was funded by Ambizione grant PZ00P2_173988 to EB from the Swiss National Science Foundation. The ASU SIMS lab is supported by the US National Science Foundation (EAR – 1819550). Part of this work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation – Earth Sciences (EAR – 1634415) and Department of Energy- GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Funding Information:
We thank James Watkins, Tanya Ewing, Sumit Chakraborty, Daniela Rubatto, Jörg Hermann and Peter Reiners for constructive discussions throughout the course of this study, as well as Thierry Adatte, Bi Wen Hua and Arnaud Magrez for assistance with powder and single-crystal XRD measurements. We are grateful for a review by Aitor Cambeses and editorial handling by Rajdeep Dasgupta. This research was funded by Ambizione grant PZ00P2_173988 to EB from the Swiss National Science Foundation . The ASU SIMS lab is supported by the US National Science Foundation (EAR – 1819550 ). Part of this work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation – Earth Sciences ( EAR – 1634415 ) and Department of Energy - GeoSciences ( DE-FG02-94ER14466 ). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357 .
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/1/15
Y1 - 2022/1/15
N2 - Ti-in-zircon thermometry has become a widely used tool to determine zircon crystallization temperatures, in part due to reports of extremely sluggish Ti diffusion perpendicular to the crystallographic c-axis in this mineral. We have conducted Ti-in-zircon diffusion experiments, focusing on diffusion parallel to the c-axis, at 1 atm pressure between 1100 and 1540 °C, with oxygen fugacities equivalent to air and the Ni-NiO buffer. There is no resolvable dependence of Ti diffusion in zircon upon silica or zirconia activity, or upon oxygen fugacity. The diffusion coefficient of Ti in zircon is found to be a weak function of its own concentration, spanning less than 0.5 log units across any profile induced below 1300 °C. Ti diffusion in zircon, parallel to the c-axis at 1 atm pressure, is well described using: [Formula presented] where R is the gas constant in J/(mol⋅K). In conjunction with diffusion coefficients for Ti in zircon perpendicular to the c-axis reported by Cherniak and Watson (2007), strong diffusion anisotropy for Ti in zircon is observed. Diffusion parallel to the c-axis is ∼4-5 orders of magnitude faster than diffusion perpendicular to the c-axis within the experimentally constrained temperature range shared between these two studies (1540-1350 °C). This difference increases if the data are extrapolated to lower temperatures and reaches ∼7.5-11 orders of magnitude between 950-600 °C, a typical range for zircon crystallization. Diffusion of Ti in natural zircons will predominantly occur parallel to the c-axis, and the Ti-in-zircon thermometer appears susceptible to diffusive modification under some crustal conditions. Temperatures calculated using this system should therefore be evaluated on a case-by-case basis, particularly when considering high-T, slowly cooled, reheated and/or small zircons.
AB - Ti-in-zircon thermometry has become a widely used tool to determine zircon crystallization temperatures, in part due to reports of extremely sluggish Ti diffusion perpendicular to the crystallographic c-axis in this mineral. We have conducted Ti-in-zircon diffusion experiments, focusing on diffusion parallel to the c-axis, at 1 atm pressure between 1100 and 1540 °C, with oxygen fugacities equivalent to air and the Ni-NiO buffer. There is no resolvable dependence of Ti diffusion in zircon upon silica or zirconia activity, or upon oxygen fugacity. The diffusion coefficient of Ti in zircon is found to be a weak function of its own concentration, spanning less than 0.5 log units across any profile induced below 1300 °C. Ti diffusion in zircon, parallel to the c-axis at 1 atm pressure, is well described using: [Formula presented] where R is the gas constant in J/(mol⋅K). In conjunction with diffusion coefficients for Ti in zircon perpendicular to the c-axis reported by Cherniak and Watson (2007), strong diffusion anisotropy for Ti in zircon is observed. Diffusion parallel to the c-axis is ∼4-5 orders of magnitude faster than diffusion perpendicular to the c-axis within the experimentally constrained temperature range shared between these two studies (1540-1350 °C). This difference increases if the data are extrapolated to lower temperatures and reaches ∼7.5-11 orders of magnitude between 950-600 °C, a typical range for zircon crystallization. Diffusion of Ti in natural zircons will predominantly occur parallel to the c-axis, and the Ti-in-zircon thermometer appears susceptible to diffusive modification under some crustal conditions. Temperatures calculated using this system should therefore be evaluated on a case-by-case basis, particularly when considering high-T, slowly cooled, reheated and/or small zircons.
KW - Ti-in-zircon
KW - diffusion
KW - diffusion anisotropy
KW - thermometry
KW - zircon
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U2 - 10.1016/j.epsl.2021.117317
DO - 10.1016/j.epsl.2021.117317
M3 - Article
AN - SCOPUS:85120639006
SN - 0012-821X
VL - 578
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 117317
ER -