Marginal basin type metavolcanites of the Hersjø Formation, eastern Trondheim District, Central Norwegian Caledonides.

Abstract

Forkortet.The more than 300 km long greenstone belt of the eastern Trondheim districtin the Caledonian Upper Allochthon displays considerable heterogeneity inlithology as well as metavolcanite geochemistry. A largely bimodal mafic-felsic volcanic assemblage comprises submarine flows, agglomerates, tuffs andtuffites. In many areas, especially in the south, these are intimately rela-ted to interlayered metapelitic units, graphitic phyllites, thin marbles andconglomerates. The metavolcanites in the investigated central area, in theHersjø Formation, show a conspicuous tripartite subdivision in theirgeochemical traits.