The Sarcheshmeh porphyry copper deposit, Kerman, Iran: A mineralogical analysis of the igneous rocks and alteration zones including halogen element systematics related to Cu mineralization processes (original) (raw)
Related papers
Journal of Geochemical Exploration, 2009
Miduk hypogene and supergene porphyry Cu-Mo mineralization occurs within the Miocene porphyritic quartz-diorite and host Eocene plagioclase-hornblende phyric andesitic pyroclastic and flow sequence. Both the host rocks were extensively altered by hydrothermal fluids to dominantly potassic, phyllic, and argillic with interstitial to distal propylitic types. Biotite-bearing assemblages from the proximal potassic zone are dark to light brown and have X phl from 0.56 to 0.68; F contents range from 0.15 to 1.8 wt.% and Cl contents range from 0.19 to 0.28 wt.%. Fluorine contents in the biotite negatively correlate with X phl and X Ti and Cl contents, and positively correlate with X phl and SiO 2 . Calculated log (fH 2 O/fHF), log (fH 2 O/fHCl), and log (fHF/fHCl) values of fluid in equilibrium with these biotites ranging from 5.5 to 6.40, 4.64 to 4.79, and − 2.54 to − 1.68, respectively. Established halogen fugacity ratio contour lines are transected by the steeper slope of measured values of biotite composition; this suggests the fluid composition, fO 2 and fS 2 of the fluids, and reaction between wall rock and hydrothermal fluids play a key role in the resultant halogen fugacities recorded in biotite that is critical to interpreting metal complexing behaviour during magmatic-hydrothermal evolution. The intercept values of F [IV(F)] and Cl [IV(Cl)] for biotite from the potassic zone are similar to those of related plutonic rocks and other porphyry Cu deposits; the IV(Cl) tend to be more Cl-rich than comparable values of common igneous rocks. F-rich to Fpoor biotite crystals from the Miduk deposit show a narrow range of F/Cl intercept values [IV(F/Cl)] consistent with porphyry Cu ore-forming fluids. ). The timing of fluid-vapour saturation affects the partitioning of F and Cl between granitic magmas, minerals, and magmatic hydrothermal fluids, which strongly controls metal complexing, and mass transport to the site of hydrothermal ore deposition . The temperature, salinity, and pH of F-and Cl-bearing fluids are also responsible for the alteration associated with porphyry emplacement
International Geology Review, 2012
Copper and gold mineralization in the Maher-Abad area, eastern Iran, is closely related to multiple episodes of emplacement of a late Eocene granodiorite into a quartz-monzonitic stock and andesitic volcaniclastic rocks. Hypogene and supergene porphyry Cu-Au mineralization occurred within the porphyritic granodiorite and quartz-monzonite host rocks extensively altered into dominantly potassic, propylitic, phyllic, and argillic assemblages. Temperature and pressure estimates using the plagioclase-hornblende thermometer and Al-in-hornblende barometer indicate that the granodiorite intruded at 758 ± 10 • C and 1.4 ± 0.2 kbar.
Ore Geology Reviews
The Sungun Porphyry copper-molybdenum deposit, in the northwestern part of the post-collisional Urumieh-Dokhtar magmatic arc, developed as a consequence of hydrothermal alteration related to the emplacement of the Sungun quartz monzonite porphyry stock into Eocene volcanic rocks. Based upon petrographic characteristics, back-scattered electron images, and compositional attributes, biotite from the Sungun Porphyry copper-molybdenum deposit was grouped into least-altered magmatic biotite (LA-Mbt), least-altered equilibrated magmatic biotite (LA-Eq Mbt), equilibrated magmatic biotite (Eq-Mbt), and secondary hydrothermal biotite (S-Hbt) types. The LA-Mbt from the mineralized zone have high TiO 2 (3.92-4.33 wt%) compared to LA-Eq Mbt (3.81-4.20 wt %), Eq-Mbt (2.75-3.85 wt%), and S-Hbt (0.27-3.00 wt%). The LA-Mbt of the barren dike is also characterized by high TiO 2 (4.17 wt% on average). Na 2 O, SiO 2 , and MnO (wt%) of biotite are systematically different between mineralized intrusions and barren ones. The highest amounts of Na 2 O (0.39-0.58 wt%) and MnO (0.11-0.18 wt %) are found in the LA-Mbt of the barren dike, which contrast with LA-Mbt of the mineralized zone having 0.08-0.15 wt% Na 2 O and 0.03-0.14 wt% MnO. Low SiO 2 values (36 wt% on average) are characteristic of LA-Mbt from the barren dike in comparison with LA-Mbt of the mineralized zone (37 wt% on average). The SO 3 contents in LA-Mbt of the mineralized zone (0.03-0.12 wt%) are much higher than those for LA-Mbt of the barren dike (0.01-0.04 wt%). The fluctuations in SO 3 content of S-Hbt reflect a complex history of formation of S-Hbt in two stages. One group of S-Hbt has SO 3 > 0.04 wt% and are principally related to the potassic (medium-high)/phyllic (low) assemblage, forming with magnetite at high oxygen fugacity, whereas the second group has SO 3 < 0.04 wt% and is related to the phyllic (high)/argillic (low) assemblage, having formed during a stage of sulfide mineralization. The calculated oxygen fugacities (ƒO 2) of 10 −15.4-10 −13.8 for the mineralized zone of the Sungun Porphyry Cu-Mo deposit lie completely within the domain of logƒO 2 > ΔFMQ+2 (where FMQ is the fayalite-magnetite-quartz oxygen buffer), typical of oxygen fugacities associated with Cu-Mo porphyry mineralization. Altered biotite types have higher Cl contents than the least altered varieties, indicating that Cl may be used as an indicator of post-magmatic hydrothermal processes. The range of F contents (0.336-0.621 wt%) for the LA-Mbt of the mineralized zone is higher than those of the LA-Mbt types of the barren dike (0.219-0.347 wt%). Fluorine in biotite may be used as an exploration vector to characterize mineralized versus subeconomic porphyry Cu-Mo systems. 1975; Parry and Jacobs, 1975); and (iii) investigating the physicochemical features of ore fluids, as well as their evolution through the entire mineralization process (Munoz, 1984; Lentz, 1992, 1994; Selby and Nesbitt, 2000). Several previous studies of biotite chemical compositions from porphyry Cu systems focused on the calculation of F and Cl contents, with the objective of identifying mineralized and barren plutons (e.g.,
Journal of Geochemical Exploration
The geochemical characteristics of four biotite types comprising least-altered magmatic biotite (LA-Mbt), leastaltered equilibrated magmatic biotite (LA-Eq Mbt), equilibrated magmatic biotite (Eq-Mbt), and secondary hydrothermal biotite (S-Hbt) types from a subeconomic low-grade porphyry Cu system named Sonajil are compared with the economic high-grade Sungun porphyry Cu-Mo deposit situated in the Western Alborz-Azerbaijan structural zone of Iran; the proximity of the two porphyry copper deposits helps to evaluate mineralization potential of the intrusive bodies. The classification scheme for biotite types is based on petrographic data, back-scattered electron images, and compositional attributes. Whereas both of the S-Hbt types at Sonajil and Sungun are related to the overlapping alteration zones of high potassic / low phyllic, the S-Hbt types at Sungun are Mg-rich and fall within the compositional field confined by two endmembers of eastonite and phlogopite. The S-Hbt types at Sonajil are Fe-rich plotting in the compositional field enclosed by two endmembers of eastonite and siderophyllite. The mean of MgO, MnO, TiO 2 , Na 2 O, SiO 2 , and F (wt%) contents of the biotites help in characterizing the geochemical features of the mineralized magmatic rocks contrasted with subeconomic intrusions. Biotite types of the Sungun Porphyry stock display much higher SO 3 contents (0.06 wt% on average) compared to those of biotite types of the Sonajil Porphyry stock (< 0.01 wt% on average). Fluorine contents (0.9 wt% F on average) in the Sungun Porphyry biotites are the highest ones, whereas the biotite types of the Sonajil Porphyry stock have 0.8 wt% F (on average). Biotite types of the Sonajil and Sungun Porphyry stocks exhibit approximately equal Cl contents (0.15 wt% on average). Magmatic biotites of the productive Sungun Porphyry stock were characterized by higher temperatures (760°C on average) compared to those of unproductive Sonajil Porphyry stock (747°C on average). The LA-Mbt types of the Sonajil Porphyry point to oxygen fugacities (ƒO 2) with values ranging from 10 −16.27 to 10 −14.40 bars, while LA-Mbt types at Sungun deposit were formed under oxygen fugacities between 10 −15.4 to 10 −13.8 bars. There is a positive correlation between the amount of Cu (wt%) in the Porphyry stocks and the wt% SO 3 in the biotites of Porphyry stocks. The hydrothermal fluids related to alteration zones in the subeconomic Sonajil have approximately the same range of log(ƒH 2 O)/(ƒHCl) and log(ƒHF)/(ƒHCl) values to those of fluids associated with other economic deposits, such as Los Pelambres and Casino. Therefore, it can be recommended that evaluating of log(ƒH 2 O)/(ƒHCl) and log(ƒHF)/ (ƒHCl) ratios of fluids in equilibrium with biotites alone cannot be a discriminating parameter. Confirmation by SO 3 (wt%) content of the biotite types, by linkage between SO 3 content of biotites and Cu grade, by halogen (wt % F and Cl) chemistry of biotite types, by halogen intercept values of F, Cl, and F/Cl, and by hydrothermal fluid halogen fugacity ratios, all illustrate the capacity of SO 3 content (wt%) of biotites to be a reliably exploration index and highlight the critical role of fluorine compared to chlorine in discrimination of unproductive and productive porphyry Cu systems.
Exploration and Mining Geology, 2007
Darreh-Zerreshk and Ali-Abad are two relatively small porphyry copper-type deposits in Yazd Province in central Iran. They are located within the central Iranian volcano-plutonic belt, formed above the collisional convergent margin of the Iranian lithospheric plate from the late Eocene to the Miocene. This paper discusses the geochemical characteristics of the igneous rocks, and 40 Ar/ 39 Ar geochronology of plutons and alteration phases associated with the Darreh-Zerreshk and Ali-Abad deposits. The deposits are spatially associated with igneous complexes that consist of older and barren granites intruded by intermediate-composition granitoids, which are the carriers of Cu mineralization. The granites have relatively high content of Nb, Y, and K, a prominent negative Eu anomaly, and were probably derived from melting of, or contamination of mantle-derived magmas by, continental crust. Porphyritic diorites, quartz monzodiorites, and granodiorites show enrichment in light rare earth and large-ion lithophile elements, depletion in middle rare earth elements, and have no negative Eu anomaly. These intermediate-composition granitoids were derived from melting of the upper mantle or lower crust, and their differentiation was controlled partly by fractionation of hornblende.
The porphyry copper deposit at Sungun is located in East Azarbaidjan, NW of Iran. The Sungun porphyries (Oligo-Miocene) occur as stocks and dikes and intruded a series of Oligocene pyroclastics and lavas, Eocene arenaceous-argillaceous rocks, and Upper Cretaceous carbonates. The porphyry stocks are divided into two groups, 1) porphyry stocks I (quartz monzo-diorite) and 2) porphyry stock II (quartz monzonite, granodiorite, and granite). Porphyry stock II hosts the copper and molybdenum ores. Numerous and various cross-cutting veinlets and micro-veinlets of quartz, sulfides, sericite, carbonates, and sulfates were developed in porphyry stock II. Three distinct types of hydrothermal alterations and sulfide mineralizations are recognized at Sungun; 1) hypogene, 2) contact metasomatic, and 3) supergene. The vertical variations in concentration of 12 elements (S, Cu, Mo, K, Rb, Ca, Sr, Na, Mg, Fe, Al, and Si) across various hypogene alteration zones at Sungun demonstrate that S, Cu, Mo, Fe, K, and Rb are mainly concentrated in the phyllic and potassic-phyllic zones where the abundance of Ca, Sr, Mg, and Na are appreciably low relative to the potassic zone. The values of Al and Si are relatively high in the supergene zones and their abundance gradually decrease downward toward the potassic zone. The copper and molybdenum are substantially localized in the phyllic and potassic-phyllic zones particularly in the central part of the mineralized porphyry stock where the rocks underwent severe stockwork-type fracturing and micro-fracturing. Their concentrations are relatively low in the potassic zone.
Journal of Asian Earth Sciences, 2003
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 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 d 34 S values of sulfides (pyrite, chalcopyrite, molybdenite, galena, sphalerite) and sulfate (gypsum) range from 2 4.6 to 20.2‰ (mean of 21.5‰) 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 d 18 O (of quartz) and d D (of fluid inclusions in quartz) values range from 8.3 to 10.2‰ (mean of 9.2‰) and 258 to 2 75‰ (mean of 2 66‰) relative to Standard Mean Ocean Water (SMOW), respectively. The calculated d 18 O values of the fluids range from 4.4‰ ðT ¼ 375 8CÞ to 7.6‰ ðT ¼ 570 8CÞ with a mean of 6.4‰. The d 18 O and d D values of the fluids lie within the typical range of magmatic waters. Based upon the lowest obtained d D 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 d 13 C (calcite) from Porphyry Stock II and associated marble aureole varies from 2 0.4 to 2.9‰ and 0.06 to 2‰ relative to the PDB Standard of the University of Chicago, respectively. The corresponding d 18 O (calcite) values range from 6 to 13.2‰ relative to SMOW. The d 13 C values lie within the sedimentary range, suggesting that there was little or almost no magmatic carbon in the hydrothermal system. In contrast, The d 18 O (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 potassicphyllic 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. q
TURKISH JOURNAL OF EARTH SCIENCES, 2014
The Chahfiruzeh deposit is a newly discovered porphyry-style copper deposit in the southern part of the Cenozoic Urumieh-Dokhtar magmatic arc of Iran. Mineralization is associated with a Miocene quartz-diorite to quartz-monzodiorite porphyritic intrusion (Chahfiruzeh porphyry) intruded into older basaltic and andesitic lava flows and pyroclastic rocks. Alteration assemblages and alteration zoning, typical of porphyry copper deposits, are well developed. Mineralization occurs in quartz-sulfide stockworks and as sulfide disseminations in the porphyritic intrusion and the immediate wall rocks. Pyrite and chalcopyrite are the main hypogene sulfide minerals; bornite and molybdenite are rare. Representative magmatic and alteration minerals, including plagioclase, amphibole, biotite, sericite, and chlorite, are analyzed, and the data are used to constrain the crystallization conditions of the magmas and the nature and evolution of the hydrothermal fluids. The fluorine-chlorine fugacity in the magma during crystallization of the Chahfiruzeh porphyry, represented by log (fH 2 O)/(fHF)-log (fH 2 O)/(fHCl) and determined from the chemical composition of magmatic biotite, ranges between 5.23 and 6.80 and between 5.05 and 5.13, respectively. A comparison to several other intrusions associated with porphyrystyle mineralization suggests that the Chahfiruzeh intrusion crystallized at relatively high fH 2 O/fHCl ratios. The intercept value (F/ Cl) of the magmatic biotite in the Chahfiruzeh porphyry ranges from 5.5 to 7.02. The calculated F/Cl intercept values for the biotite are consistent with those reported from many other porphyry copper systems. The secondary reequilibrated biotite in the intrusion is distinguished from the primary magmatic biotite by a slightly higher Mg component (X Mg = 0.53-0.68 compared to 0.62-0.66). This can be explained by the consumption of Fe to form pyrite and chalcopyrite. Chlorite occurs as an alteration product replacing magmatic biotite and hornblende, as well as hydrothermal biotite. Chlorite geothermometry indicates a narrow range between 212 and 246 °C for the formation of chlorites from various alteration zones, implying that the whole system equilibrated with a common fluid at low temperatures.
Open Geosciences
The Sungun copper–molybdenum porphyry deposit is located in the north of Varzaghan, northwestern Iran. The Sungun quartz-monzonite is the oldest mineralized intrusive body in the region and was emplaced during the Early Miocene. Eight categories of the late and unmineralized dykes, which include quartz diorite, gabbrodiorite, diorite, dacite, microdiorite and lamprophyre (LAM), intrude the ore deposit. The main mineral phases in the dykes include plagioclase, amphibole and biotite, with minor quartz and apatite and secondary chlorite, epidote, muscovite and sericite. The composition of plagioclase in the quartz diorite dykes (DK1a, DK1b and DK1c) varies from albite-oligoclase to andesine and oligoclase to andesine; in the diorite, it varies from andesine to labradorite; in the LAM, from albite to oligoclase; and in the microdiorite (MDI), it occurs as albite. Amphibole compositions are consistent with classification as hornblende or calcic amphibole. Based on their AlIV value (less ...
Ore Geology Reviews, 2014
The Khopik porphyry copper (Au, Mo) prospect in Eastern Iran is associated with a succession of Middle to Late Eocene I-type, high-K, calc-alkaline to shoshonite, monzonitic to dioritic subvolcanic porphyry stocks emplaced within cogenetic volcanic rocks. Laser-ablation U-Pb zircon ages indicate that the monzonite stocks crystallized over a short time span during the Middle Eocene (39.0 ± 0.8 Ma to 38.2 ± 0.8 Ma) as result of subduction of the Afghan block beneath the Lut block. Porphyry copper mineralization is hosted by the monzonitic intrusions and is associated with a hydrothermal alteration that includes potassic, sericitic-potassic, quartz-sericite-carbonate-pyrite (QSCP), quartz-carbonate-pyrite (QCP), and propylitic zones. Mineralization occurs as disseminated to stockwork styles, and as minor hydrothermal breccias. Some mineralization occurs in fault zones as quartz-sulfide veins telescoped onto the porphyry system. The main ore minerals are chalcopyrite and bornite with minorpyrite and magnetite and the highest Cu (0.01-0.9 wt. %), Au (N2 ppm), and Mo (b80 ppm) grades are closely associated with potassic alteration zones. Unidirectional, pre-ore stage solidification texture (UST) represented by comb-quartz layers within the potassic alteration zone formed from a hypersaline brine (57-73 wt. % NaCl equiv.), low density vapor-rich fluids (4-22 wt. % NaCl equiv.) at temperatures of 482°C to over 600°C. The isotopic composition of oxygen (δ 18 O water = 8.7-8.9 ‰) suggests that the quartz layers crystallized from magmatic-hydrothermal fluids that exsolved in the upper part of the monzonitic intrusions. Potassic alteration formed from high salinity fluids (51-73 wt. %) at temperatures between 432-592°C, and low salinity vapor-rich solutions with 11-19 wt. % NaCl equiv. Later veinlets in the QSCP zone formed from lower salinity fluids (b47 wt. % NaCl equiv.) at temperatures between 332°-400°C. The oxygen isotopic data for the early alteration zones (δ 18 O water = 9-9.3 ‰ for potassic and 7.3 ‰ for QSCP) also indicate a magmatic origin for the ore fluids. The widespread presence of Middle Eocene to Lower Oligocene magmatism and mineralization in Eastern Iran suggests the presence of another important porphyry copper belt in addition to the northwest-southeast Urumieh-Dokhtar copper belt of Iran.