GEOTHERMOBAROMETRY OF Al2SiO5-BEARING METAPELITES IN THE ARDARA AUREOLE, NW IRELAND: AN IMPLICATION FOR P-T STABILITY FIELD OF ALUMINIUM SILICATE POLYMORPHS

Document Type: Regular Paper

Author

Faculty of Earth Sciences, Damghan University of Sciences, Cheshmeh-Ali Road, Damghan, I. R. of Iran.

Abstract

Andalusite, kyanite and sillimanite occur in well-defined zones in the Ardara aureole, NW
Ireland. Temperature and pressure conditions of the Al2SiO5-bearing pelites in this aureole were
estimated using ten different calibrations of garnet-biotite thermometry and five calibrations of garnetplagioclase-
Al2SiO5-quartz barometry. The different calibrations provide different estimates of
temperature and pressure. However, using the most recent, and the best reversed experimental data give
temperatures varying from 510 to 605 ºC, and a pressure of around 4 kbar across the Ardara aureole. The
calculated temperatures for the analyzed samples are compared with published andalusite=sillimanite
equilibria, and these equilibria are evaluated in the Ardara aureole.

Keywords