Petrology and petrogenesis of Kamtal Intrusion Eastern Azarbaijan, NW Ian
The Kamtal Intrusion is located in Eastern Azarbaijan province, northwestern Iran, near the Armenian border. This body consists of an acidic part of monzogranitic composition, and an intermediate-basic part which is composed of quartz-monzonite and gabbro. The gabbro forms lenses within the intermediate rocks. Monzogranite has been intruded into the quartz-monzonite. Both monzogranites and quartz-monzonites are high-K calk-alkaline and metaluminous in composition and can be classified as I-type granitoids, while the gabbro has tholeiitic affinity. Monzogranite and quartz-monzonite are characterized by LREE-rich patterns and high LREE/HREE ratios. The similarities of their REE patterns suggest a genetic relationship among these rocks. The geochemical characters of the gabbro types indicate two different patterns: a flat pattern with low LREE/HREE ratio, and a steep pattern with high LREE/HREE ratio. The former was probably produced by high melting ratio of a depleted mantle source, and the steep pattern probably was the result of a low melting ratio of this mantle source. Negative anomalies of Nb and Ti can be seen in all rock types of the Kamtal Intrusion, which is indicative of subduction zones. The comparison of trace element variations with granitoid rocks of different tectonic settings allows observing a similarity between the Kamtal Intrusion and Andean volcanic arc granitoids. The Kamtal body is related to the VAG tectonic setting and was probably produced as a result of Khoy back-arc basin subduction beneath the Azerbaijan continental crust.