Counter-clockwise P-T history deduced from kyanite-bearing pelitic gneiss in Tenmondai Rock, Lützow-Holm Complex, East Antarctica

Abstract

This paper first reports the counter-clockwise pressure-temperature (P-T) path for the Lützow-Holm Complex in East Antarctica. The metamorphic textures of kyanite-bearing pelitic gneisses from Tenmondai Rock including earlier spinel and ilmenite inclusions, geothermobarometric data, and pseudosection modeling indicate that the pressure increases prior to the peak metamorphic conditions at around 9 ± 0.5 kbar and 770-820 °C, followed by cooling to kyanite-stability field. We conclude that these gneisses underwent granulite-facies metamorphism with a counter-clockwise P-T path, but this contrasts with the widely recognized clockwise P-T path of the Lützow-Holm Complex basement rocks in general. One plausible hypothesis we proposed could be that this counter-clockwise P-T path originated from magmatism with late compression and the rocks of the different structural levels are juxtaposed, while acknowledging that this hypothesis conflicts with previous studies and that further work is needed to clarify these issues.