Genesis of the Shams-Abad carbonate-replacement sideritic-ankeritic iron deposit, South Arak, Malayer-Esfahan metallogenic belt (MEMB), Iran: constraints from geology, fluid inclusions, and C–O isotope geochemistry

An introduction to Irish-type Zn-Pb deposits in early Cretaceous carbonate rocks of Iran

“…Barite is an important gangue mineral, replaced by coarse-grained galena and sphalerite (e.g., Irankuh and Tiran mining districts, Robat and Kuhkolngeh deposits) and some of the barite ores are economic (e.g., Robat II deposit). However, dolomitization is common in these deposits, but silicification is the major hydrothermal alteration at the Emarat (Ehya et al, 2010), Lakan, Robat, Kuhkolangeh (Peernajmodin et al, 2018;Niroomand et al, 2019), Khanabad and Eastern Haft-Savaran deposits (Mahmoodi, 2018;Rajabi et al, 2019a). Fe-rich dolomite is also a frequently observed alteration in these deposits (Boveiri et al, 2018;Mahmoodi et al, 2019).…”

“…(1) deposition of volumetrically minor, early, fine-grained, disseminated (to laminated in some of them, Fig. 6) sulphides and euhedral barite in unconsolidated sediments (Rajabi et al, 2012a;Boveiri et al, 2017;Mahmoodi et al, 2019), which in most deposits are associated with a large content of framboidal pyrite (Yarmohammadi et al, 2016;Boveiri et al, 2017;Mahmoodi et al, 2019;Peernajmodin et al, 2018;Rajabi & Mahmoodi, 2023). These sulphides and barite are followed by (2) the main coarse-grained sulphide mineralization and extensive replacement of barite, carbonates, and early sulphide laminae/bands by sphalerite, pyrite and galena, and hydrothermal minerals such as quartz and Fe-bearing dolomite within the host siltstone and/or limestone units (Fig.…”

“…Rajabi et al (2012a) relied on tectono-sedimentary and textural evidence to describe the metallogeny and origin of the Cretaceous-hosted Zn-Pb (±Ag±Ba) deposits and proposed that most of these deposits formed as a result of SedEx-like (Irish-type) ore-forming processes, related to the early Cretaceous back-arc basins which formed southwest of the Central Iranian Microcontinent (Nain-Baft basin). Recent geological and geochemical studies in these belts (Yarmohammadi et al, 2016;Boveiri et al, 2015;Mahmoodi, 2018;Peernajmodin, 2018;Peernajmodin et al, 2018;Niroomand et al, 2019;Maghfouri et al, 2019) provided evidence of unusual Zn-Pb (±Ag±Ba) mineralizing processes, by sub-seafloor replacement in an extensional environment, akin to those of the sediment-hosted Irish-type deposits.…”