Geochemistry of Gharehdagh (Ordubad) batholith and its relation with molybdenum mineralization in Gharehchilar-Gharehdarreh (northeast of Kharvana- Eastern Azarbaidjan)


1 Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran

2 Department of Geology, Payame Noor University, 19395-3697 Tehran, I. R. of Iran

3 Department of Geology, Faculty of Sciences, University of Mohaghegh Ardabili, Ardabil, Iran


The study area is located in the north of Eastern Azarbaidjan (NW Iran). In this area, mineralization of molybdenum-copper is associated with intrusive bodies and developed in the center of Gharehdagh (Gharehchilar-Gharehdarreh) batholith. Petrological and petrographic investigations show that the intrusive bodies have compositions from diorite,through monzonite and granodiorite to granite. These bodies are I-type and mainly metaluminous and calc-alkaline with medium to high potassium belonging to volcanic arcs (VAG) tectonic setting. The principal alterations zones in the mineralized areas include silicic, potassic, phyllic and propylitic. Potassic and potassic-phyllic alterations are frequently seen around the molybdenum-bearing veins and veinlets. The proportions of Mo, Si, K, Rb, Ba and REE's are increased in differentiated biotite-bearing acidic intrusive bodies. Enrichment of K, Rb and Ba and depletion of Zr, Ta, Y, Yb and Nb in intrusive bodies indicate metasomatism of upper mantle materials with subducting oceanic crust and subsequent generation of magma and its passage through relatively thick crustal rocks.The intrusive bodies associated with Mo-mineralization have often quartz-monzonitic to granodioritic composition.