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Journal of Geochemical Exploration 184 (2018) 82–96 Contents lists available at ScienceDirect Journal of Geochemical Exploration journal homepage: www.elsevier.com/locate/gexplo Fluid inclusion and stable isotope geochemistry of the orogenic–type MARK Zinvinjian Cu–Pb–Zn–Au deposit in the Sanandaj–Sirjan metamorphic belt, Northwest Iran ⁎ Sina Asadia, Shojaeddin Niroomandb, , Farid Moorea a Department of Earth Sciences, Faculty of Sciences, Shiraz University, Shiraz 71454, Iran b Department of Geology, Faculty of Science, University of Tehran, Tehran 14155–64155, Iran ARTICLE INFO ABSTRACT Keywords: The Zinvinjian polymetallic deposit occurs as veins controlled by a NW–SE trending–structure within the Quartz veins Cretaceous metamorphosed limestone and dolomite, schist, and metavolcanic rocks, northwest of Iran. The Metamorphic fluid retrograde greenschist facies metamorphism was accompanied by large–scale transpressional faulting, crack–- Fluid unmixing seal veins, infiltration of large volumes of hydrous fluid with high XCO2, and is largely overlapped by the main Stable isotopes hydrothermal events. The metamorphism has resulted in two stages of mineralization in the Zinvinjian deposit. Zinvinjian These are early–stage polymetallic sulfides–quartz and late–stage pyrite–quartz veins. The early–stage veins Iran filled fractures and are undeformed, suggesting a tensional shear setting. The late–stage veins are also mainly open–space fissure–fillings that cut or replace earlier veins. Three types of fluid inclusions (FIs), including aqueous (type–I), mixed carbonic–aqueous (type–II), and carbonic (type–III), were identified in ore–related quartz veins. The early–stage quartz contained all three types of primary FIs homogenized at temperatures of range 197–300 °C and salinities of 2.5–15.2 wt% NaCl equivalent. In contrast, the late–stage quartz veins con- tained only type–I FIs with homogenization temperatures ranging between 192 and 210 °C, and salinities of 0.2–2.7 wt% NaCl equivalent. This indicates that the metallogenic system evolved from a carbonic–rich, me- tamorphic fluid to a carbonic–poor, one through input of meteoric fluids. All three types of FIs in the early–stage minerals displayed evidence of vein formation during an episode of fluid immiscibility. Quartz δ18O (+15.3 to +19.0‰) and sulfide δ34S(−9.4 to +11.6‰) indicate isotopic equilibrium with host metasediments (rock buffering) and a metasedimentary source of sulfur during early–stage. It is believed that ore mineralization is the result of a decrease in base–metal solubility during an episode of the fluid immiscibility. This study suggests that mineralization at the Zinvinjian deposit is metamorphogenic in style, probably related to a deep–seated orogenic system. 1. Introduction world scale; (2) orebodies occur as vein systems and are structurally controlled by faults including deep–crustal shear zones; (3) ore–forming Orogenic–type deposits almost provide one–third of the global gold fluids are rich in CO2 and/or CH4; (4) mineralization depths range from production (Goldfarb et al., 2001; Groves et al., 2003; Frimmel, 2008). 5 to 20 km; and (5) they form mainly during a tectonic transition phase The possibility and potential of exploring for Cu, Pb–Zn, Fe, Ag, Au and from compression to strike–slip or extension. other metallic commodities in geologically, geochemically and struc- Retrograde hydration and/or carbonation of metamorphic rocks turally similar orogenic gold deposits have also been proposed (Chen may show a similar spectrum of behavior on scales from local vein–- et al., 2004a, 2004b; Pirajno, 2009; Pirajno et al., 2011; Asadi et al., controlled alteration to more regionally pervasive retrogression (Asadi 2014). The orogenic–type deposits commonly display the following et al., 2013a, 2014). Retrograde alteration is often associated with characteristics (Groves et al., 2003; Goldfarb et al., 2005; Yardley, economic metalliferous mineralization. Base metal– and gold–bearing 2005; Chen, 2006; Pirajno, 2009): (1) an association with active con- vein systems are common to many metamorphic belts worldwide (e.g. tinental margins in orogenic belts and widespread throughout middle Nesbitt, 1991; Robert et al., 1995; Groves et al., 2003; Chen et al., Archean to Tertiary, which are located on the metamorphic belts in the 2004a, 2004b; Yardley, 2005; Deng et al., 2008; Li et al., 2008, 2011; ⁎ ⁎ Corresponding author. E-mail address: [email protected] (S. Niroomand). http://dx.doi.org/10.1016/j.gexplo.2017.10.013 Received 9 February 2017; Received in revised form 6 October 2017; Accepted 16 October 2017 Available online 20 October 2017 0375-6742/ © 2017 Elsevier B.V. All rights reserved. S. Asadi et al. Journal of Geochemical Exploration 184 (2018) 82–96 Pirajno, 2009; Zhang et al., 2012; Ni et al., 2012). The mineralization at Kharapeh deposit (3 km South of Zinvinjian) Mineralization is commonly controlled by fold or fault systems, with is described in detail by Niroomand et al. (2011), but this study re- fault movement regulating hydrothermal fluid flow (e.g. Anderson presents the first detailed description of the Zinvinjian Cu–Pb–Zn–Au et al., 2004; Pirajno, 2009; Craw et al., 2010; Zhengjie et al., 2015). The deposit in the northwestern part of the SSMB. majority of fault–hosted base metal– and gold–bearing vein systems are This work tried to better understand the chemical history of flui- believed to have formed late in the orogenic history of the host meta- d–rock interaction at the studied deposit, including the composition morphic complex, with uplift, cooling and subsequent onset of brittle and origin of the ore fluids, as well as the thermal and hydrodynamic fracture conditions promoting the migration of mineralizing fluids regime of ore formation. Also, it focuses on the origin and composition (Schmidt Mumm et al., 1997; Anderson et al., 2004; Craw et al., 2010; of the fluid and its evolution during the mineralization process. In order Goldfarb and Groves, 2015). Groves et al. (1989) believe that or- to achieve the main objective of this study, we report new data obtained ogenic–type deposits include epigenetic, structurally, controlled sulfide from field investigations, ore geology, microthermometry, and Raman ores (e.g. chalcopyrite–sphalerite–galena–pyrite), mostly in siliceous spectroscopy of fluid inclusoins, and stable isotope compositions of vein veins along fault zones (usually strike–slip faults with normal compo- minerals. nent of movement), preferentially hosted in metamorphosed volca- no–sedimentary series. According to Waring et al. (1998) and Mateus 2. Geotectonic setting and regional structural evolution et al. (2003), orogenic–type deposits can be grouped into three major types characterized by the following metal associations: 1) Cu (Pb, Zn, The SPMC is located between the Hamedan–Tabriz volcanic arc Ag, Au); 2) Cu (Fe, Zn, Sb, Hg); and 3) Au (Co, Ni, Cu). (HTV) along the eastern boundary of Sanandaj Cretaceous volcanic arc The most prospective region for metalliferous vein systems in Iran is (SCV) and the Sonqor–Baneh volcanic arc (SBV) on the western the Sanandaj–Sirjan metamorphic belt (SSMB), trending NW–SE boundary of Sanandaj–Sirjan metamorphic belt (Azizi and Moinevaziri, (Mohajjel et al., 2003), and affected by metamorphism (greenschist to 2009; Fig. 2). Geodynamically, a crustal thinning episode during Late amphibolite facies) and an obliquely thrusted wedge, with asymme- Paleozoic to Middle Triassic times has been suggested for occurrence of trical structures in the HP–LT metamorphic rocks (Sarkarinejad and volcano–sedimentary sequences in the SSMB (e.g. Rashid et al., 2002; Azizi, 2008). Alavi, 2004; Sheikholeslami et al., 2008). During the Early–Cimmerian The relationship between metalliferous vein systems and tectonic orogeny (Late Triassic), the Tethyan oceanic lithosphere in the south settings will be explored in greater detail with regard to the compre- margin of SSMB created along the accretion axis at SW and started to be hensive review on all aspects of the evolution of the SSMB. The SSMB is consumed by subduction under the central Iranian plate after the Late a highly endowed metallogenic province, hosted several major gold and Triassic (Sheikholeslami et al., 2008). Following the subduction, two base–metal deposits (Table 1) belonging to six main ore deposit types/ main regional metamorphic events and two co–axial stages of folding styles, including; orogenic gold deposits (e.g. Qolqoleh, Kervian, Qa- emerged in the Zinvinjian area (e.g. Niroomand et al., 2011; Ghorbani, baqloujeh, Kharapeh, Alut), epithermal gold–base metal deposits (e.g. 2013). These Mesozoic Barrovian–type metamorphic events Aghdarreh, Sari Gunay, Gozalbolagh), Carlin–type deposits (e.g. Zar- (Houshmandzadeh and Soheili, 1990) range from garnet–amphibolite shuran, Akhtarchi), intrusion-related gold ( ± base–metal) systems to kyanite–quartz–mica schist and greenschist facies (Sheikholeslami (e.g. Muteh, Astaneh–Sarband, Zartorosht), metamorphogenic base–- et al., 2008). The prograde metamorphic event during the Ear- metal deposits (e.g. Bavanat), and gold–rich volcanic–hosted massive ly–Cimmerian discordance recorded the onset of the compression re- sulfide (VMS) deposits (e.g. Barika) (Nezafati et al., 2005; Aliyari et al., lated to the peak of metamorphism (700 °C and 10 kbar; Sheikholeslami 2009, 2012; Fig. 1). The SSMB, with regard to orogenic gold and et al., 2008). Peak regional metamorphic mineral assemblages probably base–metal deposits, is comparable to

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