Determination of genesis by Using geochemical and isotopic studies of iron and oxygen in magnetite ore in Gol-e-Gohar iron ore district, Sanandaj-Sirjan zone, Iran

The Gol-e-Gohar iron deposit in the Sanandaj-Sirjan zone of south-western Iran comprises six majorore bodies. The largest deposit is Gol-e-Gohar No. 3 (Gohar-Zamin) with about 643 Mt @ 53.1% Fe.Magnetite is formed in massive and brecciated shapes. Gol-e-Gohar magnetite contains Mg, Ca, and Siup to the percent range, V and Ti in the 100s ppm level, and low Cr, Co, Ni in the tens of ppm range,typical of Kiruna mineralization (especially Bafq mining district). But Chador-Malu magnetite is formedat a higher temperature than Gol-e-Gohar magnetite, therefore, hydrothermal high-T nature (magmatic ore-forming fluids), which are related to felsic magmatism (host meta-granites), and both of them are attributed to the Early Paleozoic. The oxygen isotope composition of magnetite is 4.9 ± 0.7‰ δ18 O (n = 9) and the iron isotope composition is 0.49 ± 0.05‰ δ56 Fe (n =17). These data suggest that the magnetite ore formed from a magmatic- hydrothermal (high-T) fluid in equilibrium with a granitic source. The Gol-e-Gohar iron ore district shows several similarities to the Bafq mining district, located about 400 km to the north, and seems to be a disrupted member of theKashmar-Kerman arc. Finally, according to the mentioned evidence and comparison of Gol-e-Gohar iron deposit with global samples, the genesis of mineralization in this deposit is most similar to Kiruna- type (Kiruna-type magnetite ± apatite mineralization).