Crustal thickness and its role in the magma fertility by using zircon chemistry: A case study of the Sangan magmatic complex

The Iranian plateau is located in one of the most complex geodynamic settings within the Alpine-Himalayan belt. The Sangan mining area is the largest Cenozoic skarn iron ore district in the far eastern part of the Alborz magmatic arc in Iran. Granitoid intrusions in the Sangan mining area are subdivided into the fertile Sarnowsar intrusion composed of syenite, syenogranite, and granite; and the barren Sarkhar and Bermani intrusions composed of monzogranite and syenogranite. In this study, we used the zircon geochemical composition from eight samples of Sarnowsar, Sarkhar and Bermani granitoids as an important exploration tool for reconstructing the crustal thickness and its evolution in the Sangan magmatic arc. Zircon Eu/Eu* [chondrite normalized] correlates with whole rock La/Yb, has been used to estimate the crustal thickness. Our results reveal that fertile Sarnowsar granitoids formed in the thicker crust than barren Sarkhar and Bermani granitoids.