Evidence of porphyry copper-gold mineralization in the Zardkooh prospect area, Southeastern Iranshahr

Zardkooh procpect area is located in Sistan and Baluchestan Province in southeast of Iranshahr city. In terms of structural location, the study area is located on the boundary of Makran Arc Basin with the flysch zone of eastern Iran. The geology of the area is Upper Cretaceous volcano-sedimentary rocks, which is intruded by pyroxene diorite to monzodioritic units. The dioritic intrusion contains abundant quartz veinlets with a highly altered appearance. Mineralization in this area is mostly associated with silicification and argillic alterations with a large gossan zone surrounded by propylitic alteration. The primary minerals are pyrite and chalcopyrite and secondary minerals are goethite, hematite, limonite, jarosite, chalcocite, covellite, malachite and azurite, which seen as veinlet, disseminated, colloform, and replacement textures. The maximum amount of Au, Cu, Ag, As, and Zn elements are 1.1 ppm, 5%, 3.7 ppm, more than 100 ppm, and 759 ppm, respectively. Fluids inclusion study on quartz shows that the homogenization temperature is in the range of 188° to 365 °C and the salinity is between 14.5 to 18.2% eq. NaCl. Temperature and salinity data show the role of the mixing process of high temperature and salinity fluid (probable magmatic water) with meteoric low temperature and salinity fluid in the formation of mineral reserves. The type of alterations and their development, geochemical anomalies, temperature and salinity range, geological position, lithology, and mineralogy indicate that the mineralization of Zardkooh prospect area can be the upper part of a porphyry copper-gold type system.