Geological Investigations of Main Intrusions of the Central Alborz

The intrusive bodies of Central Alborz constiute speciale distribution. And they are located near major faults, and also they are accompnied by pyroclastic rocks of the Karaj Formation.Moreover they display lithological diversity and they occur as sill, lopolith, stock and plug. These intrusive bodies blong to post upper Eocene and they are related to the Pyrenean- equivalent orogenic phase. Rregarding the geochemical results obtained by other researchers, as well as determining the nomenclature, definiton of granitoid and gabbroic bodies the composition of the above mentioned masses, fall within the calc - alkaline to alcaline range. However, most specimens are plotted in the field of type I granitoids.From the tectonic viewpoint, all of the intrusive bodies are Considered as syntectonic. Moreover, they are often of continental subduction Zone(CAG)origin, while other may be long to continental collision type(CCG), and a few are located to the island arcs(IAG).