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The Miocene Dalli porphyry Cu–Au deposit in the central part of Urumieh–Dokhtar magmatic arc is the first reported Au-rich porphyry Cu deposit in the Zagros orogenic belt. The Cu–Au mineralization is mainly hosted in diorite and quartz diorite intrusions, presenting as numerous veinlets in the altered wall rocks, with potassic, phyllic, and propylitic alteration developed. Based on the mineral assemblages and crosscutting relations of veinlets, hydrothermal mineralization–alteration occurred in at least three stages, characterized by veinlets of (1) Qtz + Kfs + Mag ± Ccp, (2) Qtz + Py + Ccp ± Bn ± Cv ± Cc and, (3) Qtz + Chl + Bt. The ore-bearing intrusions exhibit typical geochemical characteristics of subduction zone magmas, including LREE fractionated pattern, strong enrichment in LILE (Cs, Rb, Ba, Pb, and U), and depletion of HFSE, with marked negative Ti and Nb anomalies. The adakite-like ore-hosting porphyry intrusions are characterized by a systematic gradual decreasing and increasing of Y and Eu/Eu ∗ with increasing SiO 2 content, respectively. Moreover, they exhibit a significant increasing trend of Sr/Y with decreasing of Y, which indicates progressive hornblende fractionation and suppression of plagioclase fractionation during the evolution toward high water content of parental magma. A relatively flat HREE pattern with low Dy n /Yb n and Nb/Ta values may represent that amphibole played a more important role than garnet in the generation of the adakitic melts in the thickened lower crust. Based on the phase assemblages confirmed by detailed laser Raman spectroscopy analyses and proportion of solid, liquid, and gaseous components, five types of fluid inclusions were recognized, which are categorized as; (1) liquid-rich two phase (liquid H2O + vapor H2O ) (IIA), (2) vapor-rich two phase (vapor H2O/CO2 + liquid H2O ) (IIB), (3) high saline simple fluids (IIIA; liquid H2O + vapor H2O + Hl), (4) high saline opaque mineral-bearing fluids (IIIB; liquid H2O + vapor H2O + Hl + Hem + Ccp + Py) and (5) multi-phase type (IIIAB; liquid H2O + vapor H2O + Hl + Anh + Hem + Mag + Ccp). In early stage veins, the homogenization temperature of multiphase inclusions as high as 620 °C, with corresponding salinities of up to 75 wt.% NaCl equivalent represent the initial ore-forming fluids. From early to late stage veins, the gradual decrease of homogenization temperature of saline inclusions (IIIAB, IIIA, and IIIB) from 620 to 340 °C (corresponding salinities of 75–35 wt.% NaCl equivalent) may reflect fluid boiling and mixing of the early magmatic fluids with circulating groundwater. The common association of hematite and anhydrite daughter phases with the most primitive inclusions (IIIAB) in early-stage veins and the lack of CO 2 -bearing inclusions in the middle to late stage veins reveal CO 2 content and oxygen fugacity of the fluids was significantly decreased from early to main stage of sulfide mineralization (second generation of veins). It seems that magnetite crystallization and CO 2 -escape have a decisive role in oversaturation of S 2− and subsequent rapid and large-scale precipitation of sulfides in second generation of veins at the Dalli deposit. [ABSTRACT FROM AUTHOR]

Abstract: The NW–SE trending Central Iranian Volcanic Belt hosts many well-known porphyry copper deposits in Iran. It becomes an interesting area for remote sensing investigations to explore the new prospects of porphyry copper and vein type epithermal gold mineralization. Two copper mining districts in southeastern segment of the volcanic belt, including Meiduk and Sarcheshmeh have been selected in the present study. The performance of Principal Component Analysis, band ratio and Minimum Noise Fraction transformation has been evaluated for the visible and near infrared (VNIR) and, shortwave infrared (SWIR) subsystems of ASTER data. The image processing techniques indicated the distribution of iron oxides and vegetation in the VNIR subsystem. Hydrothermal alteration mineral zones associated with porphyry copper mineralization identified and discriminated based on distinctive shortwave infrared (SWIR) properties of the ASTER data in a regional scale. These techniques identified new prospects of porphyry copper mineralization in the study areas. The spatial distribution of hydrothermal alteration zones has been verified by in situ inspection, X-ray diffraction (XRD) analysis, and spectral reflectance measurements. Results indicated that the integration of the image processing techniques has a great ability to obtain significant and comprehensive information for the reconnaissance stages of porphyry copper exploration in a regional scale. The results of this research can assist exploration geologists to find new prospects of porphyry copper and gold deposits in the other virgin regions before costly detailed ground investigations. Consequently, the introduced image processing techniques can create an optimum idea about possible location of the new prospects. [Copyright &y& Elsevier]

Abstract: The Sar-Cheshmeh porphyry Cu–Mo deposit is located in Southwestern Iran (∼65km southwest of Kerman City) and is associated with a composite Miocene stock, ranging in composition from diorite through granodiorite to quartz-monzonite. Field observations and petrographic studies demonstrate that the emplacement of the Sar-Cheshmeh stock took place in several pulses, each with associated hydrothermal activity. Molybdenum was concentrated at a very early stage in the evolution of the hydrothermal system and copper was concentrated later. Four main vein Groups have been identified: (I) quartz+molybdenite+anhydrite±K-feldspar with minor pyrite, chalcopyrite and bornite; (II) quartz+chalcopyrite+pyrite±molybdenite±calcite; (III) quartz+pyrite+calcite±chalcopyrite±anhydrite (gypsum)±molybdenite; (IV) quartz±calcite±gypsum±pyrite±dolomite. Early hydrothermal alteration produced a potassic assemblage (orthoclase-biotite) in the central part of the stock, propylitic alteration occurred in the peripheral parts of the stock, contemporaneously with potassic alteration, and phyllic alteration occurred later, overprinting earlier alteration. The early hydrothermal fluids are represented by high temperature (350–520°C), high salinity (up to 61wt% NaCl equivalent) liquid-rich fluid inclusions, and high temperature (340–570°C), low-salinity, vapor-rich inclusions. These fluids are interpreted to represent an orthomagmatic fluid, which cooled episodically; the brines are interpreted to have caused potassic alteration and deposition of Group I and II quartz veins containing molybdenite and chalcopyrite. Propylitic alteration is attributed to a liquid-rich, lower temperature (220–310°C), Ca-rich, evolved meteoric fluid. Influx of meteoric water into the central part of the system and mixing with magmatic fluid produced albitization at depth and shallow phyllic alteration. This influx also caused the dissolution of early-formed copper sulphides and the remobilization of Cu into the sericitic zone, the main zone of the copper deposition in Sar-Cheshmeh, where it was redeposited in response to a decrease in temperature. [Copyright &y& Elsevier]

Abstract: The Reagan Porphyry System in southeastern Iran (Kerman Province) is associated with diorite/granodiorite to quartz-monzonitic rocks of Miocene age. Three stages of hydrothermal alteration and associated mineralization have produced new minerals, created new textural relationships and in many cases obliterated the primary character of the rocks. Potassic, phyllic and propylitic are the main hydrothermal alteration types within the intrusive stock. The early hydrothermal alteration produced a potassic assemblage in the central part of the stock; propylitic alteration occurred contemporaneously with potassic alteration, but in the peripheral parts, phyllic alteration which contains the main copper mineralization, occurred later, overprinting the earlier alteration. Phyllic is also the major alteration in the Reagan system. The early hydrothermal fluids are represented by high temperature (487–598°C), high salinity (up to 61.1wt% NaCl equiv.) liquid-rich fluid inclusions, and high temperature (397–401°C), low-salinity, vapor-rich inclusions, which are interpreted to originate from very hot orthomagmatic fluids. The brines are interpreted to have caused potassic alteration, producing first generation chalcopyrite. Propylitic alteration is attributed to a lower temperature, liquid- and Ca-rich, evolved meteoric fluid. Influx of meteoric water into the system, and mixing with magmatic fluid produced deep albitization, and shallow phyllic alteration. This influx also caused dissolution of early formed copper sulfides and remobilization of Cu into the phyllic zone. The following data indicate that the mineralizing fluid temperature was too high to produce an economic porphyry copper deposit at the studied area. Supergene alteration was restricted to a very thin blanket with uneconomic levels of Cu in the form of Cu-sulfides and oxides. [Copyright &y& Elsevier]

The porphyry copper deposit (PCD) at Sungun is located in East Azarbaidjan, NW of Iran. The magmatic suites in the Sungun area are a part of the NW–SE trending Cenozoic magmatic belt of Iran. The Sungun porphyries occur as stocks and dikes. The stocks are divided into two groups, I and II. Porphyry Stock II, ranging in composition from quartz monzonite through granodiorite to granite, hosts the Sungun PCD. Four distinct types of hypogene alterations were recognized at Sungun: (1) potassic; (2) potassic–phyllic; (3) phyllic; and (4) propylitic. Stable isotope (S, O, H, and C) studies were restricted to within the phyllic and potassic–phyllic alteration zones, where numerous cross-cutting quartz, sulfides, carbonates, and sulfate veinlets are present. The objective of these studies was to determine the origin of the ore-forming solutions, and their important components (e.g. sulfur and carbon). Twenty sulfide and four sulfate samples were taken from sulfide and gypsum veinlets within Porphyry Stock II and the associated skarn zone for sulfur isotopic analyses. The δ34S values of sulfides (pyrite, chalcopyrite, molybdenite, galena, sphalerite) and sulfate (gypsum) range from −4.6 to −0.2‰ (mean of −1.5‰) and from 10.9 to 14.4‰ (mean of 12.9‰), respectively. These values are almost analogous to those from El Salvador (Chile) and Ajo (Arizona), and Twin Buttes (Arizona), and strongly suggest a magmatic source for the sulfur at Sungun. Twenty-eight fluid inclusion-rich quartz samples from quartz veinlets beneath the supergene zones of the Porphyry Stock II were chosen for O and H isotopic analyses. The δ18O (of quartz) and δD (of fluid inclusions in quartz) values range from 8.3 to 10.2‰ (mean of 9.2‰) and −58 to −75‰ (mean of −66‰) relative to Standard Mean Ocean Water (SMOW), respectively. The calculated δ18O values of the fluids range from 4.4‰ (T=375 °C) to 7.6‰ (T=570 °C) with a mean of 6.4‰. The δ18O and δD values of the fluids lie within the typical range of magmatic waters. Based upon the lowest obtained δD values, the calculated maximum exchangeable meteoric water that might be involved in the phyllic and potassic–phyllic alteration processes was ∼20%. Fourteen calcite samples from carbonate veinlets in the Porphyry Stock II and two samples from associated marble aureole were collected for carbon and oxygen isotopic analyses. The δ13C(calcite) from Porphyry Stock II and associated marble aureole varies from −0.4 to 2.9‰ and 0.06 to 2‰ relative to the PDB Standard of the University of Chicago, respectively. The corresponding δ18O(calcite) values range from 6 to 13.2‰ relative to SMOW. The δ13C values lie within the sedimentary range, suggesting that there was little or almost no magmatic carbon in the hydrothermal system. In contrast, The δ18O(calcite) values are far lower than that of Cretaceous sedimentary carbonates which suggest that the values were influenced by those of magmatic fluids through isotopic re-equilibration. These isotopic investigations demonstrated that: (1) in contrast to some well-known PCDs, about 80% of the fluids involved in the phyllic and potassic–phyllic alterations at Sungun had a magmatic O and H isotopic signature; (2) the Upper Cretaceous limestone was the potential source of C; and (3) the sulfur had a magmatic origin. [Copyright &y& Elsevier]

[Display omitted] • Porphyry Cu deposits in the UDMB occur along the magnetic structures in high magnetic blocks. • Pb-Zn deposits in Central Iran mostly occur at boundaries between high magnetic blocks. • Most deposits in Central Iran occur in regions with thickened crust. • Newly identified hidden structures in Central Iran have potential for further exploration. Regional-scale magnetic and gravity data have been enhanced to identify major structures and distinguish geophysical blocks in order to evaluate the distribution of major mineral deposits and prospects in Central Iran. Major structures and coherent magnetic blocks have been defined from magnetic data enhanced using a combination of upward continuation and edge enhancement filters. Broad-scale regional structural architecture and coherent density blocks have been defined from gravity data enhanced using the tilt angle. Crustal thickness was calculated from Bouguer gravity data. Integration of the structures, magnetic, density and depth characteristics derived from the complementary geophysical techniques have been used to correlate and interpret the regional distribution of mineral deposits and occurrences to assist future exploration. Porphyry Cu deposits in the Kerman metallogenic zone are shown to be closely associated with major structures in high magnetic and gravity blocks that are coincident with the Tertiary volcanic units, and in areas where the crustal zone was interpreted to be more than 50 km thick. Pb–Zn deposits in Central Iranian Microcontinent are shown to be spatially associated with major structures, predominantly outside of the high magnetic response blocks, and commonly overlay the low gravity and thick crustal zones. In the north of the study area, one group of Fe deposits display a close correlation to blocks with both a high magnetic and high gravity response. Along strike to the southeast, a second group cluster is seen in an area with a moderate magnetic and a low gravity response. [ABSTRACT FROM AUTHOR]

• Quaternary volcanism near Dehaj in Kerman Province, Iran, generated high-K and adakitic suites. • High-K suite derived from melting of the thick metasomatised mantle lithosphere. • Adakite suite from melting of eclogitized lower Iranian crust, not the subducting Tethyan slab. • Mixing relationship between suites confirmed by field, petrographic and geochemical observation. • Adakitic signatures modified by garnet or amphibole FC; the latter correlated with mineralisation. Research into Arabia-Eurasia collision zone magmatism in Kerman Province, SE Iran, has largely focused on Late Cenozoic adakitic stocks or domes, with debate around lower crustal or subducted slab origins. Contemporary hawaiite-trachyandesite lava flows have been overlooked. New analyses for domes and lavas from near Dehaj show major and trace element distributions relating to two distinct compositional series. One contains medium-K domes with SiO 2 > 60 wt%, high Sr/Y and La/Yb and generally low MgO, Ni and Cr, showing high-silica adakite affinity. The other series has high-K affinity and includes both lavas and dome samples. The two suites partially mixed in the shallow crust, confirmed by fieldwork and petrography. Isotopically the two suites are indistinguishable, implying a geologically 'young' age for the source of the adakites. Given its geochemical signatures and non-relationship with the more mafic, mantle-derived high-K series, we consider the adakite series to be derived from melting of eclogitized mafic lower crust. The high-K series relates to dehydration melting of mantle deeper within the ~220 km thick lithosphere. We also explore adakitic magmas across Iran and their relationship to porphyry copper deposits. At Dehaj and several other Iranian centres, adakites are chemically controlled by garnet as a source or fractionating phase, and are barren, whereas the presence of amphibole as a key phase seems to correlate with Cu mineralisation. This study also shows the need for evidence from multiple datasets to constrain adakite genesis and warns of avoiding sampling bias towards felsic lithologies. [ABSTRACT FROM AUTHOR]

• The Haftcheshmeh Cu-Mo porphyry deposit formed from H 2 O-NaCl-CO 2 hydrothermal fluids. • Fluid inclusions record repeated CO 2 fluxes and fluid boiling. • Fluid inclusions have elevated Na, K, Fe, Mn, Cu and Mo content. • Molybdenite precipitation predates chalcopyrite. • Lithostatic to hydrostatic metal deposition occurred at 450–250 °C and 3.0–1.0 km. The Haftcheshmeh Cu-Mo porphyry deposit is located in the NW part of the Arasbaran Metallogenic-Magmatic Zone, NW Iran. Ore mineralisation is generally hosted within the gabbro-diorite and granodiorite porphyry stocks, presenting various types of hydrothermal quartz veins and veinlets associated with potassic to sericitic alteration. Stage I corresponds to barren quartz-K-feldspar-biotite-anhydrite veins (A veins), with minor metal sulphides (pyrite ± chalcopyrite), surrounded by K-feldspar and biotite halos related to potassic alteration. Stage II is described with quartz-molybdenite-chalcopyrite-pyrite-bornite-magnetite-hematite-biotite veins, predominantly occurring in the potassic alteration halos (B veins). Stage III shows pyrite-quartz-chalcopyrite ± molybdenite-galena-sphalerite associated with sericitic alteration halos (D veins). The coexistence of halite-saturated aqueous-rich and low-salinity vapour-rich fluid inclusions in the H 2 O-NaCl-CO 2 system is evidence of fluid boiling in each alteration/mineralising stage. This process was subsequently followed by meteoric water input diluting the CO 2 -bearing ore-forming fluid. LA-ICPMS data of fluid inclusions associated with the successive stages reveal elevated Na, K, Fe, Mn, Cu and Mo content. The metal content of fluid inclusions of Stages II and III is in large part due to accidentally trapped minerals. Molybdenite and chalcopyrite started precipitating between stages I and II from a metal-poor fluid. The long-duration (>1 Ma) of the magmatic-hydrothermal activity and associated CO 2 fluxes and repeated fluid boiling events lead to ore deposition at temperatures of 450 to 250 °C and at depths between 3.0 and 1.0 km from near-lithostatic to near-hydrostatic conditions. [ABSTRACT FROM AUTHOR]