SUMMARY

Permo-Triassic ultrahigh-temperature metamorphism
and continental collision in the Kon Tum massif?

Trần Ngọc Nam, Osanai Y.,
 Nakano N., Hoàng Hoa Thám

Ultrahigh-temperature metamorphic rocks in the Kon Tum massif consist of garnet-orthopyroxene-sillimanite-quartz gneisses (pelitic granulites) and garnet- clinopyroxene-orthopyroxene gneisses (mafic granulites) from the Kan Nack Complex and from the Ngọc Linh Complex as lenses and blocks, that are exposed along a NW-SE trending shear zone in Kan Nack and Đak To Kan areas. These granulite rocks were metamorphosed under ultrahigh-temperature conditions with peak conditions of T = 1050ºC and P = 12 kbar. The metamorphic P-T path is characterized by a nearly-isothermal decompression following by a nearly-isobaric cooling. Geochronological data by multi-method have been showing that the ultrahigh-temperature metamorphism of the Kon Tum massif occurred during Permo-Triassic times, ca. 245-260 Ma, similar to those of continent collision boundary between North and South China cratons. This opens a possibility that the Kon Tum massif could be a site of the Permo-Triassic collision boundary between South China and Indochina cratons.

Ngày nhận bài: 30-7-2004

Người biên tập: Phan Trường Thị