Iron mineralization in the Garagu Formation of Gara Mountain, Duhok Governorate, Kurdistan, NE Iraq: geochemistry, mineralogy and origin

The iron mineralization is hosted in carbonate beds of the Garagu Formation (Early Cretaceous) at Gara Mountain, Duhok Governorate, Kurdistan Region, NE Iraq. The Garagu Formation is composed of a series of limestone and siltstone beds with iron-rich beds in the middle part. The iron-rich limestones are iron-rich oolitic grainstone and bioclastic wackestone with hematite and goethite minerals. Geochemical results drawn from this study indicate that the percentage of iron in these beds reaches 19.73 %. Moreover, petrographical investigation of thin and polished sections reveals the presence of different types of fossils, indicating an open marine interior platform depositional environment. Different iron minerals, including hematite, goethite, siderite, pyrite and magnetite, were identified in the sections, and their geneses were related to syngenetic and diagenetic processes. The geochemical distribution of major and trace elements, as well as the V/Ni, V/(V+Ni), V/Cr and Sr/Ba ratios, indicates a reducing environment during the precipitation of carbonate sediments and a subsequent oxidizing condition during the concentration of iron minerals via diagenesis.