Fluid inclusion and stable isotope study of the Lubin-Zardeh epithermal Cu-Au deposit in Zanjan Province, NW Iran: Implications for ore genesis

Fluid inclusion, zircon U-Pb geochronology, and O-S isotopic constraints on the origin and evolution of ore-forming fluids of the tashvir and varmazyar epithermal base metal deposits, NW Iran

“…Sulfide minerals from the Tashvir deposit show a wide range of δ 34 S H2S-CDT values from −17.8‰ to −5.1‰ (average −12.7‰), and those from the Varmazyar deposit fall into a narrow range from −8.6‰ to −3.8‰, averaging −6.1‰. These data are lower than the range of mantle/magmatic δ 34 S VCDT values (±3‰; Chaussidon and Lorand, 1990) and are similar to the sulfur isotope compositions of IS epithermal base metal deposits (e.g., Aliabad-Khanchy, Zajkan, Marshoun, Abbasabad, Armaqan Khaneh, and Lubin-Zardeh) in the THMB (Figure 10B), whose sulfur is interpreted to have been originated from the magmatic system (Kouhestani et al, 2018a;Kouhestani et al, 2019a;Kouhestani et al, 2019b;Zamanian et al, 2019;Kouhestani et al, 2020;Kouhestani et al, 2022). Compared with different types of epithermal systems, δ 34 S values of the Tashvir and Varmazyar deposits are mostly consistent with the HS and IS deposits (Figure 10B).…”

“…Based on these data and related trapping pressure estimations, we conclude that ore-stage quartzsulfide veins at Tashvir and Varmazyar essentially occurred at minimum hydrostatic pressures of 10-69 and 14-68 bars, respectively. Taking the average density of the FIs, the inferred minimum metallogenic paleodepths range from 103 to 706 m at Tashvir and 143-695 m at Varmazyar, which are comparable with those of mineralization depth of the epithermal deposits worldwide (<300-1,000 m, Cooke and Simmons, 2000;Albinson et al, 2001;Simmons et al, 2005), e.g., in the THMB of northwestern Iran (200-1,400 m, Kouhestani et al, 2018a;b, 2020Zamanian et al, 2019).…”

“…Comparison of oxygen (A) and sulfur (B) isotope compositions of the Tashvir and Varmazyar deposits (this study) with those from important geological reservoirs (Hoefs, 2018), typical high-, intermediate-and low-sulfidation epithermal deposits (Field and Fifarek, 1985;Hedenquist and Lowenstern, 1994;Arribas, 1995;Albinson et al, 2001;Oyman, 2019;Sun et al, 2021 and references therein) and major intermediate-sulfidation epithermal base metal deposits of the THMB (Kouhestani et al, 2018a;b, 2020Zamanian et al, 2019).…”

“…A similar scenario has been documented for several epithermal deposits within the THMB, including Aliabad-Khanchy, Zajkan, Marshoun, Abbasabad, Rashtabad, Jalilabad, Aqkand, and Lubin-Zardeh. These deposits have δ 18 O water values ranging from +9.6‰ to -3.4‰ (Kouhestani et al, 2018a;b, 2020Zamanian et al, 2019), suggesting that their oreforming fluids were most likely magmatic-derived in the early stages, but were mixed with meteoric water in the late stages. It is consistent with the geological characteristics of these deposits that are indicative of an IS epithermal origin for these deposits.…”

“…As a part of the AHOB, the THMB was formed associated with Cenozoic closures of the Neo-Tethyan oceanic branches, i.e., Khoy-Zanjan ocean, and related microcontinental collisions (e.g., Azizi and Jahangiri, 2008;Asiabanha and Foden, 2012;Castro et al, 2013). The THMB is one of the most significant metallogenic belts in northwestern Iran and hosts many epithermal precious and base metal deposits and occurrences, such as Nikoueieh, Marshoun, Zajkan, Zehabad, Khalyfehlou, Chargar, Abbasabad, Chodarchay, Tashvir, Aliabad-Khanchy, Lubin-Zardeh, Aqkand, Jalilabad, Gulojeh, Varmazyar, Chomalou, and Shah Ali Beiglou (Figure 1B; Esmaeli et al, 2015;Mehrabi et al, 2016;Kouhestani et al, 2017;2018a;b, 2020Yasami et al, 2017Yasami et al, , 2018Mikaeili et al, 2018;Yasami and Ghaderi, 2019;, 2021Shahbazi et al, 2019;Zamanian et al, 2019;Ghasemi Siani et al, 2022). These deposits are mostly hosted by Eocene volcanic-volcaniclastic rocks of the Karaj Formation and generally cluster around the late Eocene granitoid intrusions which are thought to be genetically related (Ghasemi Siani et al, 2015;Mehrabi et al, 2016;Kouhestani et al, 2018a).…”