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Solubility of TiO2 in garnet and orthopyroxene: Ti thermometer for ultrahigh-temperature granulites

Open-File Report 2007-1047-SRP-038

By:
and
DOI: 10.3133/ofr20071047SRP038

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Abstract

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.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Solubility of TiO2 in garnet and orthopyroxene: Ti thermometer for ultrahigh-temperature granulites
Series title:
Open-File Report
Series number:
2007-1047-SRP-038
DOI:
10.3133/ofr20071047SRP038
Year Published:
2007
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
4 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Antarctica: A Keystone in a Changing World--Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. Santa Barbara, California, U.S.A.--August 26 to September 1, 2007