Characteristics of fluid inclusions in the Cenozoic volcanic-hosted Kushk-e-Bahram Manto-type Cu deposit of central Iran

Abstract

The Kushk-e-Bahram Manto-type Cu deposit is located in central Iran, within Eocene to Oligo-Miocene volcanic strata which occur in the central part of the Uremia-Dokhtar Magmatic Arc (UDMA). Propylitization, silicification, argillization and carbonatization are the main types of alteration to have affected the pyroclastic and volcanic rocks. There are high amounts of oxide minerals, including malachite, azurite, hematite, magnetite and goethite. Three types of primary FIs have been determined in the Kushk-e-Bahram deposit, namely; I: Two-phase liquid-rich FIs (L+V), II: Mono-phase liquid FIs, III: Two-phase vapour-rich FIs which have been identified based on petrographical studies. Based on FI studies of co-existing quartz and calcite, homogenization temperatures (Th) must have been between 67 and 228°C, with an average of 158°C. Moreover, salinity is between 14.0-30.3 wt% NaCl, equivalent to a 19.6% average. Fluid density values vary from 0.8 to 1.1 gr/cm3. Based on FI data and related diagrams, the depth of their trapping was estimated to be <200 m and ore formation occurred at pressures of <50 bars. Consequently, mineralogy, host rock and FIs character-istics in the Kushk-e-Bahram deposit are similar to the Manto-type Cu deposits in Mesozoic-Cenozoic volcanic belts of Iran and South America.