The Tibbit Hill Formation is a group of metamorphosed volcanic rocks located in the Waterloo area of Quebec, Canada. The formation is predominantly metabasaltic, with these rocks enclosing a band of metafelsites 15 x 2.5 km. Protolith volcanics relate to the opening of the Iapetus Ocean, later metamorphosed to greenschist facies during the formation of the Appalachian foldbelt in which they reside. As a result, the primary igneous mineralogy has been wholly replaced, converting metafelsites to muscovite-quartz-albite schists. The mineralogy is consistent with rhyolitic compositions, with HFSE and REE chemistry suggesting the protoliths were peralkaline and comenditic. Agpaitic indices are <1, however this is explained by the loss of alkalis during metamorphism. Detailed major and trace element analysis can be found in Kumarapeli et al. (1989).
KUMARAPELI, P.S., DUNNING, G.R., PINTSON, H. & SHAVER, J., 1989. Geochemistry and U-Pb zircon age of comenditic metafelsites of the Tibbit Hill Formation, Quebec Appalachains. Canadian Journal of Earth Sciences 26 pp 1374-1383