Polymetamorphosed gneisses of Proterozoic age crop out on Roan Mountain, North Carolina–Tennessee, near the western edge of the Blue Ridge belt. These gneisses display Grenville-age, granulite-facies assemblages, including two-pyroxene metabasites and gar-net-sillimanite-orthoclase metapelites. All gneisses were intruded by diabase dikes of the late Precambrian Bakersville Gabbro. Paleozoic amphibolite-facies metamorphism locally formed garnet and amphibole in mafic rocks and kyanite in metapelitic rocks.

Two pyroxene geothermometry and mineral stability curves define temperature-pressure ranges of 750–847 °C and 6.5–8.0 kbar for the granulite-facies metamorphism. This metamorphism probably occurred within the lower crust at depths of 23–28 km. Pressure-temperature conditions for the major Paleozoic metamorphism are not well constrained but are estimated to be 700–740 °C and 7.5–9.0 kbar.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page of A Proterozoic granulite-facies terrane on Roan Mountain, western Blue Ridge belt, North Carolina–Tennessee
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.