Study of composition, source and tectonic setting of metapelite rocks from Mahneshan complex, NW, Iran

Abstract

The Precambrian rocks of Mahneshan Complex in Northwestern Iran were affected by regional and contact metamorphism. At the Mahneshan Complex different types of igneous and metamorphic rocks are exposed. Metamorphic rocks including metapelites, amphibolites, metavolcanite, para-gneiss, metaperidotites and serpentinites. Metapelites are foliated at two directions. Exact petrographic and petrofabric studies on them show that three metamorphic phases including two regional and one contact are affected the rocks. Andalusite, staurolite, kyanite and garnet minerals are crystallized during second regional metamorphic phase. Geochemistry studies of metapelites shows that, Composition of old meta-sedimentary rocks (source of metapelites), are shale and greywacke. Discrimination diagrams indicate an arc related tectonic setting for the source of Mahneshan metapelites. Sources of Mahneshan metapelites are intermediate felsic igneous rocks (rhyolite or andesite) base on Geochemistry of immobile elements.