Submicron polyphase inclusions in garnet from the Tananao Metamorphic Complex, Taiwan: a key to unravelling otherwise unrecognized metamorphic events

Kyanite and staurolite occur in the Tananao Metamorphic Complex as submicro n inclusions in almandine-rich garnet from a metamorphosed palaeosol weathe ring horizon. near Hoping, eastern Taiwan. Quartz, rutile/brookite and zirc on are also found as associated submicron inclusions in garnet. Employing t he reaction ilmenite + kyanite + quartz = almandine + rutile, and the break down of staurolite and quartz as thermo barometers., these submicron-scale minerals formed at >8.3-8.8 kbar and <660-690<degrees>C. This P-T estimate is different from that (i.e. 5-7 kbar and 530-550 degreesC) derived from ma trix minerals. which include almandine-rich garnet, muscovite. chlorite, ch loritoid, plagioclase, quartz and ilmenite. These results suggest that subm icron inclusions in garnet-like materials may record portions of the otherw ise undocumented prograde path or provide information about previous metamo rphic events and thus yield new insights into orogenic belts.