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.
Highlights
A great number of important porphyry, epithermal, and base metal ore deposits are formed in the Tethyan Eurasian Metallogenic Belt (TEMB) [1,2,3,4]
The Shah-Ali-Beiglou area is situated in the northwestern part of the Tarom-Hashjin metallogenic province (THMP) and comprises a sequence of Eocene and Oligocene volcanic and volcaniclastic rocks, which were intruded by Oligocene plutonic rocks (Figure 3)
The Shah-Ali-Beiglou is an example of base metal-silver epithermal deposit in the Tarom-Hashjin metallogenic province, occurring in the breccia zones
Summary
A great number of important porphyry, epithermal, and base metal ore deposits are formed in the Tethyan Eurasian Metallogenic Belt (TEMB) [1,2,3,4]. In the Iranian part of the TEMB, Eocene and Oligocene base metal vein-type deposits formed in three belts: 1. The magmatic activity of the AAMB in the NW Iran initiated after Late Cretaceous compressional deformation related to the initial collision of the Arabia and Eurasia plates (e.g., [8,9,10,11]). The AAMB occurred in an extensional tectonic setting during Late Paleocene-Eocene [12,13]. The northwestern part of the AAMB includes two mineralized subzones named the Ahar-Arasbaran Belt (AAB)
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