TitaniQ under pressure: The effect of pressure and temperature on the solubility of Ti in quartz

Jay Thomas, E. Bruce Watson, Frank S. Spear, Philip T. Shemella, Saroj K. Nayak, Antonio Lanzirotti

Research output: Contribution to journalArticle

227 Citations (Scopus)

Abstract

Quartz and rutile were synthesized from silica-saturated aqueous fluids between 5 and 20 kbar and from 700 to 940°C in a piston-cylinder apparatus to explore the potential pressure effect on Ti solubility in quartz. A systematic decrease in Ti-in-quartz solubility occurs between 5 and 20 kbar. Titanium K-edge X-ray absorption near-edge structure (XANES) measurements demonstrate that Ti4+ substitutes for Si4+ on fourfold tetrahedral sites in quartz at all conditions studied. Molecular dynamic simulations support XANES measurements and demonstrate that Ti incorporation onto fourfold sites is favored over interstitial solubility mechanisms. To account for the P-T dependence of Ti-in-quartz solubility, a least-squares method was used to fit Ti concentrations in quartz from all experiments to the simple expression, where R is the gas constant 8.3145 J/K, T is temperature in Kelvin, Xquartz Tio2 is the mole fraction of TiO2 in quartz and aTio2 is the activity of TiO2 in the system. The P-T dependencies of Ti-in-quartz solubility can be used as a thermobarometer when used in combination with another thermobarometer in a coexisting mineral, an independent P or T estimate of quartz crystallization, or well-constrained phase equilibria. If temperature can be constrained within ±25°C, pressure can be constrained to approximately ±1. 2 kbar. Alternatively, if pressure can be constrained to within ±1 kbar, then temperature can be constrained to approximately ±20°C.

Original languageEnglish (US)
Pages (from-to)743-759
Number of pages17
JournalContributions to Mineralogy and Petrology
Volume160
Issue number5
DOIs
StatePublished - 2010
Externally publishedYes

Fingerprint

Quartz
solubility
quartz
Solubility
temperature
Temperature
X ray absorption
effect
pressure effect
Pressure effects
least squares method
phase equilibrium
pressure effects
rutile
Crystallization
Titanium
pistons
Silicon Dioxide
Phase equilibria
Pistons

Keywords

  • Quartz
  • Solubility
  • Thermobarometry
  • Thermometry
  • Titanium
  • XANES

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

TitaniQ under pressure : The effect of pressure and temperature on the solubility of Ti in quartz. / Thomas, Jay; Watson, E. Bruce; Spear, Frank S.; Shemella, Philip T.; Nayak, Saroj K.; Lanzirotti, Antonio.

In: Contributions to Mineralogy and Petrology, Vol. 160, No. 5, 2010, p. 743-759.

Research output: Contribution to journalArticle

Thomas, Jay ; Watson, E. Bruce ; Spear, Frank S. ; Shemella, Philip T. ; Nayak, Saroj K. ; Lanzirotti, Antonio. / TitaniQ under pressure : The effect of pressure and temperature on the solubility of Ti in quartz. In: Contributions to Mineralogy and Petrology. 2010 ; Vol. 160, No. 5. pp. 743-759.
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