Geochemistry, Petrogenesis and dating of lamprophyric dykes in the Kaleybar area, NW Iran

In the south and south east of Kaleybar city, lamprophyric dykes associated with basanitic and andesitic dykes intruded in the Cretaceous-Paleocene flysch-type and volcanic rocks. The lamprophyric dykes show typical lamprophyric texture with biotite and pseudomorphs of clinopyroxene phenocrysts. According to mineralogy and geochemistry, the studied lamprophyres belong to calc-alkaline group and are minette. The studied lamprophyres show enrichment in the large ion lithophile and light rare elements and depletion in the high field strength elements. Geochemical features of the studied lamprophyres confirm that they are originated from 1-3 % partial melting of a garnet lherzolite mantle source with phlogopite veinlets that previously have been metsomatized by subduction related melts. According to biotite crystals Ar-Ar dating, the studied lamprophyres emplaced during Middle Oligocene (31-32 Ma.) in a volcanic arc tectonic setting.