Mineral chemistry and formation conditions of calc-silicate minerals of Qozlou Fe skarn deposit, Zanjan Province, NW Iran

Abstract

The Qozlou Fe skarn deposit is located at the Abhar-Mahneshan belt of the Central Iranian Zone. It is associated with Upper Eocene porphyritic granite that intruded into the Upper Cretaceous impure carbonaceous rocks. The Qozlou granite has high-K calc-alkaline affinity and is classified as subduction-related metaluminous I-type granitoids. Skarn aureole in the Qozlou is composed of endoskarn and exoskarn zones, with the exoskarn zone being the main skarn and mineralized zone. It includes garnet skarn, garnet-pyroxene skarn, pyroxene skarn, epidote skarn, and pyroxene-bearing marble sub-zones. The Qozlou Fe deposit is 300 m long and 5-30 m wide. Magnetite is the main ore mineral associated to pyrite, chalcopyrite, and pyrrhotite. Garnet, clinopyroxene, actinolite, epidote, calcite, and quartz occur as gangue minerals. Covellite, hematite, and goethite were formed during the supergene processes. The ore and gangue minerals have massive, banded, disseminated, brecciated, veinveinlets, replacement, and relict textures. EPMA data indicate that garnets have andradite-grossularite compositions (Ad 39.97-100-Gr 0-49.62) and clinopyroxenes have diopsidic composition (En 29.43-42.5-Fs 14.31-20.99-Wo 43.08-50.17). Based on mineralogical and textural criteria, skarnification processes in the Qozlou skarn can be categorized into three discrete stages: (1) isochemical (metamorphic-bimetasomatic), (2) metasomatic prograde, and (3) metasomatic retrograde. Anhydrous calc-silicate minerals (garnet and clinopyroxene) were formed during the prograde metasomatic stage, while ore minerals and hydrous calc-silicate minerals were formed during the retrograde ore-forming sub-stage. Temperature and ƒO 2 conditions range between 430 and 550°C and 10 −26 and 10 −23 , respectively, for the metasomatic prograde stage. The retrograde metasomatizing fluids had likely ƒS 2 = 10 −6.5 and temperatures < 430°C at the beginning of the ore-forming sub-stage.

Genesis and Evolution of the Yolindi Cu-Fe Skarn Deposit in the Biga Peninsula (NW Turkey): Insights from Genetic Relationships with Calc-Alkaline Magmatic Activity

“…When these exsolved fluids penetrate country rocks, they cause abrupt and rapid hydrofracturing in the crystallizing magma (Şaroluk granitoid rocks) and the nearby wall or host rocks (Torasan Formation). This hydrofracturing is also a consequence of bimetasomatic and decarbonation alteration events [101], which form regions of distinct skarn zones in the study area: endoskarn and multiple exoskarn zones.…”

Mineralogical Studies of the Tanjung Iron Mine in the Bone, South Sulawesi: Implication for AMD Generation

“…Based on the textural relationship, it was indicated that magnetite was the first ore minerals formed, most likely through the hydrothermal process at relatively higher temperature environment [11]. The oxidation of magnetite has led to the formation of hematite and goethite via supergene process [12].…”

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

“…These deposits are commonly associated with subaerial volcanism and calc-alkaline to alkaline intrusions that formed in island arcs and continental arcs at convergent plate margins, as well as in intra-arc, back-arc, and postcollisional rift settings (White and Hedenquist, 1990;Cooke and Simmons, 2000;John, 2001;Sillitoe and Hedenquist, 2003;Simmons et al, 2005). The Alpine-Himalayan Orogenic Belt (AHOB) hosts numerous small-to large-sized porphyry Cu-Mo (Au), orogenic Au, epithermal Au, and Pb-Zn-Cu (Ag), and skarn Fe and polymetallic deposits (e.g., Hou and Wang, 2008;Xie et al, 2017;Richards, 2015;Hou and Zhang, 2015;Kouhestani et al, 2015;Moritz et al, 2016a, b;Searle et al, 2016;Mokhtari et al, 2019). The Tarom-Hashtjin Metallogenic Belt (THMB) is located in the central part of the AHOB (Figure 1A).…”