Petrology and Petrogenesis of Alkaline and Calc-Alkaline Lamprophyres in the NW Iran

In the northwestern Iran mica-and amphibole-rich lamprophyres crop out mainly as dyke and they cut Pre-Pliocene strata. They exposed in the Arasbaran, Eslamy Peninsula, and Mishu range. According to the mineralogy andmineral chemistry, amphibole-rich lamprophyres have kaersutite type amphiboles and diopside phenocrysts in the matrix of same mafic minerals,feldspars, and altered glass. These lamprophyres in some thin sections have olivine and phlogopite. Mica-rich lamprophyres include phlogopite and diopside phenocrysts in the matrix of same mafic minerals, abundant glass and secondary minerals. According to the mineralogy, mineral chemistry, and geochemistry, amphibolerichlamprophyres are alkaline and show camptonite-sannaite composition but mica-rich lamrophyres are calc-alkaline and represent minettecomposition. Alkaline lamprophyres represent characteristics of OIB type magma while calc-alkaline lamprophyres show characteristics of magmas originated in the subduction dominant tectonic setting. Sorkheh amphibole bearing lamprophyres show both alkaline and calc-alkaline type lamprophyres. Regarding to geochemical features both calc-alkaline and alkaline lamprophyres originated from heterogeneous mantle with different proportions of spinel, garnet and hydrous minerals (e.g. phlogopite and amphibole). Calc-alkaline lamprophyres originated from a mantle enriched in phlogopite and alkaline lamprophyres originated from lithospheric mantle that metasomatised by deep mantle and enriched in amphibole. Both mentioned mantles associated in the petrogenesis of the Sorkheh amphibole- bearing lamprophyres. The lamprophyres were emplaced in the post collisional tectonic setting.