Genesis of Sulfide Mineralization in the Gallala Area Kurdistan Region, Iraq: Constraints from Major and Trace Elements of Sulfide Ore Mineralization and their Host Rocks

Abstract

This article presents and interprets new geochemical data from the Gallala sulfide mineralization, situated in the Choman District of the Kurdistan Region of Iraq close to the Iraq and Iranian border. The host rocks belong to the Walash-Naopurdan Group, which developed in the Paleocene-Eocene age in the Zagros Suture Zone. The ore mineral assemblage of the Gallala area consists of pyrite, chalcopyrite, sphalerite, and magnetite. The mineral chemistry and geochemical analysis indicate that there is a significant variation in concentrations of pyrite, chalcopyrite, sphalerite, and magnetite from the Gallala mineralization. The trace element characteristics of the sulfide mineralization and their host rocks indicate that the ore-forming materials were derived from hydrothermal fluids being interacted with the igneous rocks. The trace element signatures and REE distributions of the studied samples, tectonically lead to suggest island-arc and back-arc environments in the Gallala area. Additionally, the REE patterns of the Gallala sulfides indicate the ore-forming fluids are related to arc-related hydrothermal systems. The integration of geochemical features along with the chemistry of ore mineralization such as the Selenium/Sulfur ratio of pyrite, Co/Ni ratios from both pyrite and chalcopyrite, the Zn/Cd values from the sphalerite, and the petrogenetic discriminate diagrams of magnetite reveal that the genesis of the sulfide mineralization can be attributed to volcanogenic to hydrothermal ore-formations with high to medium temperatures origin.