Abstract:

The trace element content in rutile was analyzed by both electron microprobe (EMP) and laser ablation inductively coupled plasma mass spectrometry (LAICPMS) for HP granulite in the Bashiwake area of the South Altun HPUHP metamorphic belt. Results indicate that Zr content in rutile from HP granulite measured by EMP coincides with these measured by LAICPMS within experimental error. Zrinrutile thermometry of Thomkins et al. (2007) yields temperatures that agree with previous results by traditional thermometry calibrations， and thus it is more suitable for temperature estimation for HP granulite in Bashiwake area， whereas the other two calibrations developed by Zack et al. (2004) and Watson et al. (2006) give systematically higher or lower temperatures. Calculated Zrinrutile temperatures in fresh HP granulite range from 890 ℃ to 962 ℃ at 20 GPa， representing the peak metamorphic temperature of high pressure granulite. Zrinrutile temperatures in retrogressed HP granulite yielded temperatures between 764 ℃ and 822 ℃. These results further show that HP granulites in the Bashiwake area of the South Altun HPUHP metamorphic belt experienced peak conditions at ultrahigh temperature and high pressure， followed by medium temperature granulite facies conditions related to retrogression.

Key words: South Altun, Bashiwake, HP granulite, Zrinrutile thermometry