Petrological characterization of the Cenozoic igneous rocks of the Tafresh district, central Urumieh-Dokhtar Magmatic Arc (Iran)

Abstract

We report a petrographic and whole-rock geochemical characterization of the Cenozoic volcanic rocks cropping out in the Tafresh area of the central Urumieh-Dokhtar Magmatic Arc of Iran. The investigated rocks range mainly from basaltic andesite to dacite, and are considered to be genetically linked by (mostly) closed-system evolutionary processes involving fractionation of ferromagnesian minerals and plagioclase first, then of plagioclase and lesser amphibole (plus minor clinopyroxene) and finally of plagioclase with lesser alkali feldspar and minor amphibole. These represent a typical calcalkaline series emplaced in a subduction-related setting, producing the observed LILE-enriched and HFSE-depleted geochemical signature. The basaltic andesite compositions likely derived from an unsampled hydrous primitive melt equilibrated in a spinel-bearing metasomatized peridotite source, evolving at shallow to moderate crustal depths.