HR: 09:30h
AN: V51E-07 [Abstracts]
TI: SiO2 Solubility in Rutile at High Pressure and Temperature
AU: Ren, Y
EM: y.ren@gl.ciw.edu
AF: Institute of Geology, CAGS, Key Laboratory of Continental Dynamics of the Ministry of Land and
Resources, Beijing, 100037
China
AU: * Fei, Y
EM: fei@gl.ciw.edu
AF: Carnegie Institution of Washington, Geophysical Laboratory
5251 Broad Branch Rd., NW, Washington, DC 20015
United States
AU: Yang, J
EM: yangjsui@ccsd.org.cn
AF: Institute of Geology, CAGS, Key Laboratory of Continental Dynamics of the Ministry of Land and
Resources, Beijing, 100037
China
AU: Bai, W J
EM: yangjsui@ccsd.org.cn
AF: Institute of Geology, CAGS, Key Laboratory of Continental Dynamics of the Ministry of Land and
Resources, Beijing, 100037
China
AU: Xu, Z Q
EM: yangjsui@ccsd.org.cn
AF: Institute of Geology, CAGS, Key Laboratory of Continental Dynamics of the Ministry of Land and
Resources, Beijing, 100037
China
AB:
Silicon-bearing rutile has been found in nature. The extent of SiO2 solubility in rutile and the nature of its origin
are still not clear. At high pressure, SiO2 takes rutile structure with 6-coordinated Si. The high-pressure phase of
SiO2 may enhance its solubility in rutile because possible isovalent exchange in octahedral site. In this study, we
report new experimental results on SiO2 solubility in rutile up to 23 GPa and 2273 K. Starting materials are mixtures of
powdered TiO2 and SiO2, with compositions of (Ti0.5Si0.5)O2, (Ti0.93Si0.07)O2, and
(Ti0.75Si0.25)O2. The mixtures were loaded into either a platinum capsules (for a 10/5 assembly) or a rhenium
capsules (for an 8/3 assembly). The experiments were carried out using multi-anvil high-pressure apparatus with rhenium
resistance heater. Sample temperatures were measured with a type-C thermocouple. The quenched samples were recovered and
prepared for electron microprobe analyses. TiO2-rich and SiO2-rich phases are produced in all the quenched samples.
The analyses showed that the solubility of SiO2 in rutile increases with increasing pressure, from 1.5 wt% SiO2
at 10 GPa to 3.8 wt% SiO2 at 23 GPa for a given temperature of 2073 K. The solubility also increases with increasing
temperature, from 0.5 wt% SiO2 at 1773 K to 4.5 wt% SiO2 at 2273 K for a given pressure of 18 GPa. On the other
hand, the solubility of TiO2 in coesite or stishovite is very limited, with an average of 0.6 wt% TiO2 over the
experimental P-T ranges. Lower oxygen fugacity decreases the solubility of SiO2 in rutile, whereas water has little
effect on the solubility of SiO2 in rutile. Our experimental data are extreme useful for determine the depth of origin
for the SiO2-bearing rutile in nature.
DE: 3612 Reactions and phase equilibria (1012, 8412)
DE: 3620 Mineral and crystal chemistry (1042)
DE: 3630 Experimental mineralogy and petrology
DE: 3652 Pressure-temperature-time paths
DE: 3654 Ultra-high pressure metamorphism
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005