Deciphering multiple metamorphic events in high-grade metamorphic terranes : A case from the Amery area of East Antarctica

It is very difficult to determine the nature, timing and P-T path of each metamorphic event in multiple high-grade metamorphic terranes. This is also a frontier issue in the field of metamorphic geology. Careful geochronology coupled with detailed structural analysis and petrographical observations remains the best way to correlate ages to metamorphic events. Using this method, researchers have successfully deciphered the Grenvillian and Pan-African high-grade metamorphic events in the Amery area of East Antarctica. The affecting ranges, ages and P-T evolutions of two metamorphic events are roughly revealed, but many scientific problems have been not solved yet. In general, the development of two- or multi-phase compressional-extensional deformation cycles with different structural orientations, the preservation of different (clockwise or anticlockwise) or discontinuous P-T paths, and the existence of two- or multigroups of metamorphic ages can be taken as indicators of multiple metamorphism occurring in a metamorphic terrane. There are two unsolved petrological problems on studies of multiple high-grade metamorphic overprinting. The first is what early metamorphism control on late metamorphic recrystallization. The second is how late metamorphism overprint on early metamorphic assemblages. It is obvious that searching the overprinting mechanism, metamorphic behavior and controlling factor of multiple high-grade metamorphic events is a tough task in future for petrologists.