Solubility of TiO2 in garnet and orthopyroxene: Ti thermometer for ultrahigh-temperature granulites
We report the TiO2 solubility in garnet and orthopyroxene coexisting with rutile calibrated from experimental data at pressures 7–20 kbar and temperatures 850–1300°C in two Antarctic granulite systems.The Ti would substitute for the tetrahedral Si, whereas we could not find positive evidence of the coupled substitution of M-Ti (M is Mg or Fe) for Al-Al in octahedral sites as well as the interstitial substitution of -Ti ( is avacancy)
for M-M in triangular-dodecahedral sites of garnet at ultrahigh-temperature (UHT) metamorphicconditions.The TiO2 content of garnet increases with temperature and decreases with pressure. In orthopyroxene Ti substitutes for atoms in the tetrahedral and octahedralsites.The Ti content of orthopyroxene increases with temperature and
increases with pressure.Titanium solubility in garnet and orthopyroxene is not so sensitive to pressure change as
compared with temperature dependence given by following empirical equations: ln (X Grt;IVTi/XGrt;IVSi)= -15366/T +5.962 and ln ( XOpx;IV
Ti/XOpx;IVSi)=-11367=T +3.107 where X is the mole fraction of Ti or Si on the tetrahedral sites and temperature is given in Kelvin.
Citation Information
Publication Year | 2007 |
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Title | Solubility of TiO2 in garnet and orthopyroxene: Ti thermometer for ultrahigh-temperature granulites |
DOI | 10.3133/ofr20071047SRP038 |
Authors | Toshisuke Kawasaki, Yoichi Motoyoshi |
Publication Type | Report |
Publication Subtype | USGS Numbered Series |
Series Title | Open-File Report |
Series Number | 2007-1047-SRP-038 |
Index ID | ofr20071047SRP038 |
Record Source | USGS Publications Warehouse |