The Shah-Ali-Beiglou Zn-Pb-Cu (-Ag) Deposit, Iran: An Example of Intermediate Sulfidation Epithermal Type Mineralization

Abstract

The Shah-Ali-Beiglou epithermal base metal-silver deposit is located in the Tarom-Hashjin metallogenic province (THMP) in northwestern Iran. This deposit is hosted by quartz monzonite dikes of Oligocene age and surrounded by andesite to trachyandesite volcanic and volcaniclastic rocks of Eocene age. The subvolcanic rocks in the study area vary in composition from quartz-monzonite to monzonite and have metaluminous, calc-alkaline to shoshonitic affinity. These rocks have I-type geochemical characteristic and are related to post-collisional tectonic setting. The mineralization occurs as NE-SW and E-W-trending brecciated veins controlled by strike-slip and normal faults, which are associated to the Late Oligocene compressional regime. The mineral paragenesis of the vein mineralization is subdivided into pre-ore stage, ore stage, post-ore stage, and supergene stage. Pre-ore stage is dominated by quartz, sericite, and subhedral to anhedral pyrite as disseminated form. Ore-stage is represented by quartz, sphalerite (from 0.1 mol % to 4 mol % FeS), galena, chalcopyrite, tetrahedrite-tennantite, minor seligmannite and enargite, as vein-veinlet, cement and clast breccias. Post-ore stage is defined by deposition of quartz and carbonate along with minor barite, and supergene stage is characterized by bornite, chalcocite, covellite, hematite, goethite, and jarosite. The ore mineralization is associated with the silicic alteration. The styles of alteration are silicic, carbonate, sericitic, chloritic, and propylitic. Fluid inclusions in sphalerite have a wide range of salinities between 0.35 wt % and 21.4 wt % NaCl equivalent and homogenization temperatures range from 123 to 320 • C. The isotopic values of sulfides vary from 2.8 to 6.7 suggesting a magmatic source for the sulfur. In the present study, based on geological setting, alteration style of the host and wall rocks, main textures, mineral assemblages, composition of ore minerals, and structural features, it is suggested that the mineralization in the Shah-Ali-Beiglou is similar to intermediate-sulfidation style of epithermal deposits.

Petrography and Geochemistry of Hydrothermal Alteration in the Low-Sulfidation Epithermal Kestanelik Au Deposit, Biga Peninsula, NW Turkey

“…For example, the alteration mineral association of quartz ± calcite ± adularia ± illite in low-sulfidation deposits, including Au-Ag, or Ag-Pb-Zn ores [18,19]. Globally, the various alteration types occur at different intensities in the silicified vein [20][21][22][23], monzonite [24], diorite porphyry [5,6], granite-granodiorite porphyry [22,25,26], and metamorphic [22,27]-volcanic rocks [8,21,28].…”

Petrography and Geochemistry of Hydrothermal Alteration at the Low Sulphidation Epithermal Kestanelik Au Deposit, Biga Peninsula, Nw Turkey

“…The alterations in low and high sulphidation epithermal deposits are arranged as propylitic, argillic, advanced argillic, silicic, sericitic (phyllic), respectively [18]. In the world, the alterations occur at different intensities in the quartz vein [26][27][28][29], monzonite [30], diorite porphyry [8,9], granite-granodiorite porphyry [28,31,32], metamorphic [28,33], and volcanic rocks [11,27,34]. Compared to the wealth of publications in the literature on origin research of epithermal Au-Ag deposits, it can be seen that there are very few detailed clay mineralogy studies on the alteration zones of epithermal deposits [34][35][36][37][38][39][40][41][42].…”

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

“…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).…”