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The Iju Cu porphyry is located in the NW part of the Kerman Magmatic Copper Belt (KMCB). It is related to a ~ 9 Ma granodiorite porphyry intrusion, with three main stages of hydrothermal activity. The homogenization temperatures for the fluid inclusions are in the ranges of 200–494 °C, and their salinities vary from 4.0 to 42.8 wt% NaCl equiv., which are typical magmatic-hydrothermal fluids. The δ34S values of sulfides range from −0.4 to +3.2 ‰ (V-CDT), and the δ34S values of anhydrite samples range from +11.6 to +16.8 ‰. The δ34S values of sulfides show a narrow range, implying a homogeneous sulfur source. The oxygen isotopic composition of hydrothermal water in equilibrium with quartz samples ranges from +3.4 to +6.0 ‰ (V -SMOW) consistent with the hydrothermal fluids having a magmatic signature, but diluted with meteoric waters in the main mineralizing stage. The most important factors responsible for metal precipitation in the Iju porphyry deposit are fluid boiling, oxygen fugacity decrease and cooling followed by dilution with meteoric water. The primary fluids of the Iju Cu deposit are characterized by relatively high temperature and moderate salinity, and are CO 2 -rich, indicating a typical post-collisional porphyry system. [ABSTRACT FROM AUTHOR]

The Kerman Cenozoic magmatic arc (KCMA), located on the southeast of the Central Iranian volcano-plutonic belt, hosts some world class porphyry copper deposits. Temporally, the deposits overlap with the Alpine–Himalayan collision, which has some key implications for the existence or lack of copper mineralization during orogenic arc system development. Transition from normal calc-alkaline arc magmatism in the Eocene-Oligocene (Jebal Barez-type) to adakite-like calc-alkaline magmatism (Kuh Panj-type) in the mid-late Miocene-Pliocene reflects the onset of collision between the Afro-Arabian and Eurasian plates in the Kerman Cenozoic arc segment. The aim of this review is to determine the role of Cenozoic magmatic events in the development of economic to sub-economic porphyry copper mineralization in the southeastern parts of the Central Iranian volcano-plutonic belt. In order to discriminate between the various magmatic systems (KCMA) involved in that development, a geochemical investigation is carried out using samples collected from all important deposits in the region (this study) and previous published data by earlier researchers in this region. It is evident from these data that the collisional Neogene Kuh Panj porphyry suite is distinctly more evolved than the pre-collisional Eocene-Oligocene Jebal Barez granitoids, with relative enrichments in incompatible elements, Sr/Y (> 55), and La/Yb (> 20), slightly positive Eu anomalies (Eu n /Eu* ≈ 1), and depletions in HFSE, with [La/Sm] n ≈ 4.6–6.6 and [Dy/Yb] n ≈ 1.0–2.0, and relatively non-radiogenic Sr isotope signatures ( 87 Sr/ 86 Sr = 0.7042–0.7047). In contrast, Jebal Barez granitoids exhibit low Sr/Y (< 21) and La/Yb (< 9) ratios, negative Eu anomalies (Eu n /Eu* ≈ 0.5), and enrichment in HFSE and radiogenic Sr isotope signatures ( 87 Sr/ 86 Sr = 0.7053–0.7075). The temporal along with lithogeochemical and isotopic changes, reflect a progressive transfer of the melting zone from the juvenile mafic lower crust (garnet–free amphibolite) into garnet–amphibolite. This transfer is the result of compressional stress along with tectonic shortening during Eocene-Oligocene (~ 30–35 km crustal thickness) to mid-late Miocene (~ 45–55 km thick or 12–15 kbar). The absence of volcanism, under prevailing compressional conditions (mid-late Miocene-Pliocene), prevented the escape of SO 2 from the adakite-like, sulfur-rich, highly oxidized magmas (“closed porphyry systems”), which allowed formation of several world-class to giant mineral deposits. Volcanic activity during formation of the subvolcanic Eocene-Oligocene porphyries allowed development of “open porphyry systems”, which, in turn to partial outgassing of volatiles, and therefore, far less significant mineral deposits. [ABSTRACT FROM AUTHOR]

This study presents copper isotope compositions of mineralized whole-rock samples from the Kerman porphyry copper belt (KPCB) southeast of the Urumieh Dokhtar magmatic arc. Samples for this study were specifically collected from the Sar Cheshmeh, Meiduk, Iju, SarKuh, Darreh Zar, Bagh Khoshk, and Jebal Barez deposits and investigated to study the application of Cu isotopes to mineral exploration. While in the leached cap zone of the deposits, δ65Cu values range between −3.41 to 5.82 ‰ (avg. 0.42 ‰), in the supergene enriched zone of these deposits the relatively higher δ65Cu content ranges from 5.18 to 8.71 ‰ (avg. 7.17 ‰), and in the hypogene zone, the intermediate δ65Cu values range from 1.49 to 7.31 ‰ (avg: 4.36 ‰). Most measured δ65Cu values in these investigated porphyry copper deposit are positive, which indicates the presence of a Cu − enriched zone. In the enriched leached cap zones, the δ65Cu of the Darreh Zar and Sar Cheshmeh deposits are overall higher relative to the Iju, Meiduk, SarKuh, and Bagh Khoshk deposits, and these higher δ65Cu values are associated with the highest Cu grade and tonnage in the Sar Cheshmeh and Darreh Zar deposits. It is therefore plausible to conclude that the higher δ65Cu value in the leached areas are diagnostic of the high concentration of copper. These findings are complemented by the presence of Cu (II) carbonates, silicates, and Fe − oxides in each sample that has resulted in the enrichment of 65Cu, relative to the remnant sulfides with a wider copper isotope range. In addition, there is a general shift toward higher δ65Cu isotope values relative to the inferred precursor minerals. The overall apparent weathering and oxidative dissolution is likely to have generated isotopically heavier fluids and lighter residual minerals. The elevated δ65Cu of the bulk samples from porphyry Cu deposits in KPCB is consistent with a preferential loss of 63Cu into fluids during the segregation of aqueous fluid–melt. This is best explained by several pulses of hypogene magmatic fluid which led to repeated enrichment in 65Cu in the magmatic system. It is plausible to conclude that copper isotope values in these mineralized samples can be used as an effective exploration tool to identify buried porphyry Cu systems. • Copper isotopic composition of whole rock samples shows a wide range up to 8 ‰. • High Cu isotope can be an indicator for the presence of an inherited Cu–enriched magma. • Oxidative dissolution generate isotopically heavier fluids and lighter residual minerals. • Whole-rock Cu isotope seem closely related to the Cu grade and tonnage of KPCB deposits. • Whole-rock Cu isotope is a helpful tool for prospecting means ore exploration. [ABSTRACT FROM AUTHOR]

Abstract This investigation of leached caps in Meiduk and Parkam porphyry copper deposits (PCD) in Kerman Cenozoic magmatic arc (KCMA) of SW Iran indicated that the fertility of supergene enrichment zones may be inferred from the mineralogical and geochemical characteristics of their associated leached caps. That is, the indigenous mature leached caps characterized by strong leaching of Cu, large ion lithophile elements (LILEs), and high field strength elements (HFSEs), commonly form above intrusions where supergene enrichment is strongly developed. Mineralogically, these leached caps (e.g., SE Meiduk) are characterized by abundant hematite and minor goethite (Hem:Gt ≈ 5.48), whereas immature leached caps (e.g., NW Meiduk and Parkam) are associated with poorly developed supergene enrichment zones characterized by abundant goethite (Hem:Gt ≈ 0.56 for NW Meiduk and 0.38 for Parkam), boxwork textures, secondary copper minerals and remnant pyrite. Calculated rock quality designation (RQD) from drilling cores in Meiduk deposit also revealed the relation between joint density and the extent of supergene enrichment. Moreover, increasing the rare earth elements (REEs) content in the immature and fewer REEs concentration in the mature leached caps also reflects the fertility of supergene enrichment zone in PCDs. Highlights • The fertility of supergene zone is reflected in the mineralogical and geochemical characteristics of their associated leached caps. • Calculated rock quality designation (RQD) revealed the extent of supergene enrichment. • REEs are the best geochemical indicators for supergene enrichment development. [ABSTRACT FROM AUTHOR]

The present work attempts to discriminate between the geochemical features of magmatic-hydrothermal systems involved in the early stages of mineralization in high grade versus low grade porphyry copper systems, using chemical compositions of silicate and sulfide minerals (i.e., plagioclase, biotite, pyrite and chalcopyrite). The data indicate that magmatic plagioclase in all of the porphyry copper systems studied here has high An% and Al content with a significant trend of evolution toward AlAl 3 SiO 8 and □Si 4 O 8 endmembers, providing insight into the high melt water contents of the parental magmas. Comparably, excess Al and An% in the high grade deposits appears to be higher than that of selected low grade deposits, representing a direct link between the amounts of exsolving hydrothermal fluids and the potential of metal endowment in porphyry copper deposits (PCDs). Also, higher Al contents accompanied by elevated An% are linked to the increasing intensity of disruptive alteration (phyllic) in feldspars from the high grade deposits. As calculated from biotite compositions, chloride contents are higher in the exsolving hydrothermal fluids that contributed to the early mineralization stages of highly mineralized porphyry systems. However, as evidenced by scattered and elevated log ( f H 2 O)/( f HF) and log ( f H 2 O)/( f HCl) values, chloride contents recorded in biotite could be influenced by post potassic fluids. Geothermometry of biotite associated with the onset of sulfide mineralization indicates that there is a trend of increasing temperature from high grade to low grade porphyry systems. Significantly, this is coupled with a sharp change in copper content of pyrite assemblages precipitated at the early stages of mineralization such that Cu decreased with increasing temperature. Based on EMPA and detailed WDS elemental mapping, trace elements do not exhibit complex compositional zoning or solid solution in the sulfide structure. Nevertheless, significant amounts of Cu and Au are contained in pyrite assemblages as micro- to nano-sized inclusions, especially in the high grade fertile porphyry deposits. However, unexpectedly high concentrations of Te, Se, and Re may be associated with early stage of sulfide mineralization, especially when there is no epithermal lithocap. This may highlight the significance of trace metals partitioning in the sulfides formed at the early stages of mineralization in PCDs. [ABSTRACT FROM AUTHOR]

The Miocene Sarkuh porphyry Cu deposit is located in the southwestern part of Urumieh-Dokhtar Magmatic Arc (UDMA) in Iran. Compared with the neighboring giant Sarcheshmeh porphyry Cu deposit, this is a low-grade sub-economic porphyry Cu system (110 million tons @ 0.26 % Cu) characterized by an unusual abundance of magnetite. The present work tried to answer the question of whether or not there are differences in the hydrothermal system of Sarkuh, resulting in the lack of considerable mineralization. In this way, the mineral associations and EMPA data of magnetite were considered to distinguish the different stages of magnetite crystallization reflecting the magmatic-hydrothermal evolution of the Sarkuh deposit. They include (1) magmatic stage magnetite, including magnetite inclusions within primary silicate minerals (i.e., plagioclase and biotite), (2) pre-ore stage magnetite associated with potassic alteration assemblages, (3) main ore stage magnetite tightly associated with sulfide mineralization, and (4) late stage magnetite forming overgrowths on the sulfides. The results of EPMA analysis confirm that magnetite of these four stages differ in Mn, Fe, Ti, Mg, Al, Cr, and V concentrations. Higher V concentrations are found in the magmatic and pre-ore stages, whereas Al and Si reach the highest in the ore and late stages. Our data show that increasing fluid-rock interaction and changes in the oxygen fugacity, especially during the main ore stage extending to the late stage, are key factors controlling the trace element partitioning of magnetite. Most of ore stage magnetite formed at temperatures >500 °C and high temperatures prevailed during it. Magnetite crystallization after the main stage of sulfide mineralization accompanied by (partial) martitization indicate the increase of oxygen fugacity towards the late hydrothermal stage. This could explain why the ore and late stage magnetites show chemical similarities to those from sulfur-poor iron oxide copper‑gold (IOCG) deposits rather than porphyry deposits. • Sarkuh porphyry Cu deposit is characterized by unusual abundance of magnetite. • Four stages of magnetite crystallization could reflect the magmatic-hydrothermal evolution. • Al and Si reach the highest in the ore and late stages. • Ore and late stage magnetites show chemical similarities to sulfur-poor IOCG deposits. [ABSTRACT FROM AUTHOR]