Search

The Urumieh-Dokhtar magmatic arc (UDMA), Iran, hosts giant to small porphyry Cu ± Au deposits associated with Miocene post-collisional magmatism. Previous studies suggested that the ore-bearing suites are derived from chalcophile element-rich juvenile lower crustal igneous rocks, and that metal contents in the magmas play an important role in the formation of porphyry Cu ± Au deposits in this region. This study investigates the whole-rock major, trace, and platinum group element (PGE) geochemistry, as well as zircon trace element geochemistry, of six porphyry Cu ± Au ore-bearing suites and three barren suites in the central and southeastern UDMA. The aim is to revisit their petrogenesis and understand the factors controlling the formation of post-collisional porphyry Cu ± Au deposits. The high Mg# and Cr and Ni contents of the most mafic variants of ore-bearing and barren rocks suggest that they are primarily derived from the mantle. However, the ore-bearing magmas from the small Dalli Cu–Au porphyry and barren magmas from central to southeastern UDMA experienced substantial crustal assimilation during evolution. The evolved ore-bearing magmas exhibit high La/Yb and Sr/Y ratios, along with concave upward chondrite-normalized REE patterns and high zircon Ce/Nd and Eu/Eu* values, suggesting that they have undergone amphibole dominant differentiation under hydrous and oxidized conditions. In contrast, the barren magmas are characterized by lower whole-rock La/Yb and Sr/Y and zircon Ce/Nd and Eu/Eu* values with flatter REE patterns, implying plagioclase dominant differentiation. The ore-bearing suites, except for the Dalli suite, have systematically higher Pd and Pt contents than barren suites with highly fractionated PGE patterns (high Pd/Ir). The chalcophile element fertility of the ore-bearing suites, as indicated by high Pd/MgO and Pd/Pt ratios, is comparable to that observed in porphyry Cu deposits found elsewhere. This similarity suggests that the Cu contents of the magma likely played acrucial role in the formation of the porphyry Cu deposits in the central and southeastern UDMA. Late sulfide saturation or small amounts of sulfide segregation may have led to the high Cu and moderate Pd contents of the ore-bearing magmas until the late stage of differentiation. In contrast, early sulfide saturation resulted in significant depletion in all PGE and Cu in the barren magma. The fractionated PGE patterns of the ore-bearing magmas could have arisen due to two potential processes. Firstly, they may have resulted from fractional crystallization of Cr-spinel in the early sulfide undersaturated differentiation. Secondly, the patterns might have been inherited from partial melting of metasomatized lithospheric mantle. The systematic geochemical differences between ore-bearing and barren suites suggest that the more hydrous and oxidized nature and higher Cu contents of the ore-bearing magmas substantially increase the porphyry Cu ore potential in the central and southeastern UDMA. [ABSTRACT FROM AUTHOR]

The Kighal porphyry Cu deposit, in the Arasbaran magmatic belt (AMB), is hosted by Late Eocene to Oligocene volcanic rocks and Miocene high–K calc–alkaline subvolcanic intrusions. The Miocene quartz monzonite stocks host porphyry–style Cu mineralization characterized by potassic, phyllic, argillic, and propylitic alteration zones and an advanced argillic lithocap. The Ar–Ar dating of secondary biotite from the potassic alteration and alunite from the lithocap yields precise ages of 20.10 ± 0.18 Ma and 19.15 ± 0.21 Ma, respectively, documenting the evolution of the hydrothermal system over ~ 1 Myr. Hydrothermal rutile occurs in the deposit from the proximal potassic to distal propylitic alteration zones, and their Ti–Fe–Cr–V–W contents can be used as a fertility indicator which suggests a decrease from the proximal zones towards the distal zones. The geochemical fingerprints of the Kighal (and in general the AMB) igneous rocks reflect a post–collisional arc setting. Their distinctly high Th/Yb and Ta/Yb ratios are typical of high–K calc–alkaline intrusions, suggesting that their parental melts were derived from an enriched upper mantle source modified by slab–derived components. Their 87Sr/86Sr(i) (0.70427 to 0.70452) and 143Nd/144Nd(i) (0.512712 to 0.512754) ratios reveal that the magmas experienced moderate crustal assimilation during their magmatic evolution, also supported by increasing Th/La and 87Sr/86Sr(i) and decreasing εNd(i) values with increasing SiO2 content. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the intrusions (18.67 to 18.84, 15.60 to 15.66, and 38.83 to 39.06, respectively) reveal a crustal origin. Hence, a post–collisional arc setting is proposed for NW Iran, in which mantle–derived mafic melts underwent a MASH process and ascended into shallow magma chambers in the upper crust associated with moderate crustal contamination, which account for the formation of large–scale porphyry Cu mineralization in the AMB. [ABSTRACT FROM AUTHOR]

This comprehensive research has been conducted to consider the distribution of PTEs in the surface sediments of a recently developed Dar-e-Allo copper mine in dependence on the potential ecological and human health risks. Field sampling was carried out discreetly at preselected sampling spots including the natural background, the streams around the mine, waste rock drainages, evaporative deposits, sediments containing Fe oxy-hydroxides and secondary phases. Distribution of target elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Se, and Zn) showed high levels of crustal elements. As regards, Fe, Al, and S are identified to exist as the most copious elements in the earth's crust, so have the major portion of potentially toxic elements (PTEs) in the sediment concentrations. Evaluating environmental indices reflected that in general, Cu, S, and Mo have a higher quota of contamination in sedimentary systems. the pollution load index (PLI), modified contamination degree (mCd), Contamination factor (Cf), Sediment potential index (SPI), Geo-accumulation index (Igeo) and Contamination degree (Cd) confirm that sedimentary systems of mining area are heavily contaminated by PTEs and were not found within the guideline acceptable values. The potential ecological risk index (PERI) displayed a high or severe risk level for Cu with a peak in green–blue sediments containing secondary minerals. The results of total carcinogenic risk (TCRs) show that As has high toxicity level and carries a risk of carcinogenicity among children and adults. The TCRs for Cd, Cr, Ni, and Pb with carcinogenic potential are found only in children and they are classified as the prime concern elements that have serious dangers to children's public health. The results of contamination source presumed that the sources of PTEs contamination were principally geogenic along with the anthropogenic sources in the study area. Therefore, the present study has highlighted the implication of human health risks of PTEs in sedimentary systems of copper mining, also will grant advice for prime stakeholders, including mine managers, Environmental Protection Agency, the government and public organizations in connection to protecting the environment, aquatic biota and consumer's health. [ABSTRACT FROM AUTHOR]

Obtaining spatial correlation between estimated physical parameters and corresponding lithological features is always challenging in geophysical exploration. This research provides various estimated geophysical models at two porphyry centers in the Dalli Cu–Au deposit in central Iran to characterize hydrothermal alteration zones, host lithologies, and mineralization. The dataset used in this research consists of ground magnetic and direct current electrical resistivity and induced polarization data and core drilling geochemical analyses. Constraints such as appropriate depth weighting via calculation of the power spectrum and Euler deconvolution of the magnetic data were used to relieve the non-uniqueness nature of magnetic data inversion. The resulting estimated models from 3D inversion of magnetic data to 2D inversion of direct current electrical resistivity and induced polarization data inversion indicated that higher chargeability zones and strong copper and Au mineralization zones are spatially associated with a significant modulus of magnetic susceptibility gradient. The models also confirm the presence of a U-shape pyrite shell at the Dalli porphyry deposit. Overlaying the geochemical drilling data on this shell showed that the inner boundaries correspond well with the zones of significant Cu–Au mineralization. Comparing the geophysical models with the host lithologies indicated that the inner part of the primary quartz diorite porphyry as the host rock dominantly has potassic alteration, with lower Cu–Au grades, higher magnetic susceptibility, and lower resistivity. In contrast, the main Cu–Au mineralization concentration occurs between the quartz diorite intrusion and the pyrite shell that is located mainly in the wall rock andesite porphyries, where magnetic susceptibility is decreased. [ABSTRACT FROM AUTHOR]

This study was planned with the aim of identifying the nature and circumstances of the high-graded central core and increasing trend of copper content through depth of 1000 m in Miduk PCD. Mechanisms of high-grading, refer to hypogene enrichment (HE), in PCDs poorly understood. Two main hypotheses for hypogene enrichment formation assumed addition of extra copper to the system, alternatively hypogene leaching and enrichment. In order to obtain alteration-mineralization-geochemical pattern both horizontally and vertically, all macroscopic data extracted from relogging of 6800 m' drill core along an east–west profile, compiled with microscopic observations from studying of 550 thin-polished sections and copper grades of 3400 samples analyzed by XRF and ICP-OES. Our findings proved hypogene enrichment events at deposit. HE evidences in macroscopic and microscopic scales identified almost as various replacement textures between Fe-Cu sulphides and also vein-reopening by later Cu-mineralization and new generation of disseminated or vein type mineralization. In addition, appearance of dark halo, as consuming intermediate chalcocite phase, around pyrite and chalcopyrite which gradually evolves as bornite, also extruding extra iron as fibrous hematite at the outer edge of bornite product replaced chalcopyrite, partially replacement of bornite and chalcopyrite to hypogene chalcocite and covellite-digenite in deep potassic are other HE evidences in the case study. Here, we draw on microscopic observations and SEM-BSE-EDS results, secondary hypogene genesis for some of bornite and chalcopyrite as a hypogene enrichment evidence. Observations from relogging show that potassic alteration has a relatively good preservation in the center of the deposit from depth to surface, but affected by intense overprinting of subsequent alterations towards margins. Evident function of ore-leaching at margins, also elevated copper grades in central parts of the deposit strongly suggest leaching-fixation mechanism. Where buffer potential of the rock is preserved copper fixation and where it totally eliminated almost complete leaching of copper happened. Consequently, we introduce leaching-fixation as index processes in hypogene enrichment at the case study. We suggest that identifying the nature of hypogene enrichment processes and its characterizations not only improve understanding about PCD's hydrothermal evolution, but also achieve exploration indicators, furthermore, industrial benefits in the production line. [ABSTRACT FROM AUTHOR]

Gardaneh Salavat porphyry copper system is located in the northwest of Iran. It comprises a quartz diorite to diorite porphyritic intrusion that created extensive alteration haloes in the host rocks. Despite all technical considerations, the exploration activities did not yield to ore discovery. As the matter of fact, all of the geological, geophysical, and geochemical characteristics of a porphyry Cu-Au deposit exist but there is no economic mineralization. Detailed examinations suggest that the only reasonable explanation can be related to the infertility or low metal endowment of the porphyritic intrusion. The reasons include (1) anomalous ranges of Cu, Au, and Mo rather than economic ore grades, (2) weakly development of potassic alteration, (3) probably sulfur saturation of magma that occurred before intrusion emplacement in the host rocks, and (4) probably low metal endowment in the regional scale and the lack of known porphyry copper deposits in close neighborhoods. It is tried to test the proposed hypothesis with the introduced fertility indicators based on major and trace element geochemistry. However, current fertility indicators could not prove or reject the proposed hypothesis for Gardaneh Salavat porphyritic intrusion because of the high-K calc-alkaline to shoshonitic nature of the intrusive rocks together with the unavailability of relatively fresh/unaltered samples. This case study is notable to examine because (1) it shows that characterization of fertile from barren intrusions seems to be as important as vectoring towards concealed porphyry copper deposits, especially while dealing with deep exploration targets that are associated with high financial risks, and (2) it highlights the inefficiencies and uncertainties in introduced magma fertility indicators for porphyry copper intrusions. As a result, it is of high importance to conduct an overarching investigation on other possible fertility indicators as a fundamental need for the future of the exploration industry. [ABSTRACT FROM AUTHOR]

The Kighal and Bormolk porphyry copper deposits (PCDs) are known subeconomic deposits and are ~10 km south of Sungun, the world-class copper mine in NW Iran. The deposits are located in the Azerbaijan plateau, within Alborz, Zagros, and Caucasus Mountain ranges, having undergone active tectonics, including uplift and thrust-folding from the Cimmerrian Orogeny. The sub-economic nature of the Kighal and Bormolk deposits, despite their relatively close distance and age and lithologic similarity to those of the Sungun deposit, has been discussed. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Landsat 8 Operational Land Imager (OLI) imagery were used to map alteration patterns and lineaments associated with these deposits. In order to discriminate alteration minerals of the deposits in comparison with those in the Sungun deposit, the ASTER image was processed using False Color Composite (FCC), Band Ratio (BR), Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), and Mixture-Tuned Matched-Filtering (MTMF) techniques, which recognize seven alteration types in the Kighal‒Bormolk area and three types in the Sungun area, including its more intense alteration systems. The results were verified by field observations, mineralogical, and X-ray diffraction (XRD) studies. Also, lineament extraction of DEM and Landsat 8 OLI data by Envi 5.1, Geomatica, ArcGIS 10.6, and Rockworks 16, displayed a lower density of fault intersections in the Kighal‒Bormolk area. Additionally, NW‒SE trending lineaments of the Sungun deposit, which is in accordance with most of the valuable porphyry copper deposits in Iran, are taken into account. [ABSTRACT FROM AUTHOR]

This paper reports microthermometric and noble gas isotope data for fluid inclusion assemblages (FIAs) with evidence of phase separation, i.e. coexisting vapor-rich and halite-saturated inclusions, hosted in the early-formed quartz stockwork veins and post-magmatic quartz eye crystals in two economic porphyry Cu deposits (PCDs; Sar Cheshmeh and Miduk) and two sub-economic prospects (Sar Kuh and Abdar) from the Kerman porphyry copper belt (KPCB), Iran. The multiphase halite-saturated inclusions (i.e., Type I) in all studied PCDs and prospects had the highest homogenization temperature (Th = 525–594 °C) and salinities (63–73 wt% NaClequiv), whereas vapor-rich inclusions (Type II) had lower Th (362–460 °C). Fluid inclusion data show that like economic PCDs, the sub-economic prospects were formed in a fertile hydrothermal system and benefited from a mineralizing fluid, which evolved from a primary hot (mostly > 400 °C), metal-rich and oxidized fluid (as evidenced by the presence of opaque- and hematite-bearing fluid inclusions) of unknown salinity, which underwent a phase separation process to form both brine and vapor phases in the early stage of mineralization. The helium abundance and its isotopic composition document a mantle-derived magmatic source for the primary ore fluid in the formation of the studied PCDs and prospects (3He/4He ratios ranging from 0.46 to 2.8 Ra, corresponding to a mantle He contribution in ore fluids between ~ 7 and 45%). However, subsequent hydrothermal processes, i.e., vapor–brine phase separation, fluid-rock interaction with crustal rocks, and mixing with meteoric pore water containing dissolved atmospheric (e.g., Ne and Xe) and some crustal noble gases (e.g., Ar), changed the initial noble gas composition of the magmatic ore fluid to predominantly atmospheric- and crustal-like compositions. A significant proportion of mantle-derived He (up to 45%) in high-temperature (513–594 °C) and high-salinity (61.5–73 wt% NaClequiv) FIAs may indicate the existence of buried, economic, porphyry Cu mineralization in the Abdar prospect; therefore, it is suggested to be a possible target for further exploration. Comparing the He and Ar noble gas isotope composition in porphyry copper systems of different size and economic importance in this study showed that the ore-forming fluids of the outsized PCD (i.e., Sar Cheshmeh) have higher contributions of crustal-derived fluids characterized by predominantly radiogenic noble gas signatures (4He and 40Ar) than the smaller PCDs. This could have been achieved by a prolonged hydrothermal circulation in a large volume of crustal rocks containing radiogenic noble gases under a long-lived heat regime resulting from a deeply emplaced and slowly cooled composite intrusive body. [ABSTRACT FROM AUTHOR]

The Masjed Daghi porphyry-epithermal Cu-Au-Mo deposit in the northern Arabian-Eurasian collision zone of the Alborz Magmatic Assemblage, NW Iran, is hosted by an early Miocene quartz monzodiorite to diorite intrusion that intruded Eocene volcanic rocks. Potassic, phyllic, argillic, and propylitic alterations associated with four stages of porphyry mineralization (I to IV) are distinguished. Late high-sulfidation epithermal veins of mainly quartz or quartz-barite are enclosed in concentric zones of advanced argillic, argillic, silicic, and propylitic alterations. Poly-phase brine inclusions from the stage ΙΙ porphyry mineralization have homogenization temperatures (Th) between 305 and 600 ºC, with salinity from 30.2 to 73.9 wt% NaCl equivalent. Brines inclusions of stages ΙΙΙ and ΙV have Th from 192 to 466 ºC and salinity from 20.6 to 59.2 wt% NaCl equivalent. These brine inclusions were trapped with vapor-rich inclusions, which have Th from 122 to 318 ºC and low-moderate salinity of 0.3 to 22.3 wt% NaCl equivalent. Fluid inclusions from quartz and sphalerite in epithermal veins yielded Th ranges of 123–298 °C and 121–218 °C, and salinity ranges of 1.9–12.8 and 1.9–11.2 wt% NaCl equivalent, respectively. The δ34S values of sulfide minerals from stages ΙΙ and ΙΙΙ porphyry mineralization vary from + 0.9 to + 2.3‰, whereas the δ34S values of sulfides from the late epithermal veins range from + 1.2 to -1.1‰. These characteristics are consistent with a similar magmatic source for both the fluids of porphyry mineralization and subsequent high-sulfidation epithermal veins. The Masjed Daghi deposit that represents a telescoped porphyry-epithermal system of copper–gold mineralization in the center and peripherals of the early Miocene intrusive stocks shows both similarities and differences to other Tethyan deposits in the Alpine-Himalayan orogenic belt. [ABSTRACT FROM AUTHOR]

Copper is an essential material for electrical conductivity and is a good conductor for heat. The porphyry copper deposits (PCD) are one of the most important resources of copper, where the determination of copper grade is one of the most important issues. The finding complex relationship between copper grade and kind of rocks is a major change for modelers. This study employed the adaptive neuro-fuzzy interface system (ANFIS) and multi-layer perceptron (MLP) to estimate the copper grade in PCDs. The Henry gas solubility optimization (HGSO), weed algorithm (WA), and moth flame optimization (MFO) were applied to set the parameters of the MLP and ANFIS models. The Iju PCD, as one of the important copper deposits in the Kerman province of Iran, was chosen as a case study for predicting the copper grade. Three scenarios were used as input to the models. The first scenario used the latitude and altitude of boreholes as input and the second scenario used the longitude and altitude of boreholes as input. The third scenario used the latitude, longitude, and altitude of boreholes as input. Results of the first scenario indicated that the percent bias of the ANFIS model was 0.26, while it was 0.19, 0.22, and 0.24 for the ANFIS-HGSO, ANFIS-MFO, and ANFIS-WA models. The accuracy of models indicated that the integration of ANFIS and HGSO decreased the root mean square error (RMSE)of the ANFIS-MFO, ANFIS-WA, and ANFIS models about 14%, 21%, and 27%, respectively, in the training phase in the second scenario. The RMSE for the ANFIS-HGSO was 1.98 in the training phase, while it was 2.31, 2.45, and 2.67 for the ANFIS-MFO, ANFIS-WA, and ANFIS models, respectively, in the third scenario. The accuracy of three input scenarios was compared with that of ANFIS-HSGO. The Mean absolute error of ANFIS-HSGO for the third input scenario was 67% and 40% less than for the first and second input scenarios in the testing phase. The third scenario was the best input scenario. Uncertainty analysis for all the models showed that the least value of uncertainty belonged to the ANFIS-HGSO. This study also used an inclusive multiple model to estimate copper grade based on providing a synergy among multiple models. The utilization of an inclusive multiple model based on the outputs of the hybrid and standalone ANFIS and MLP models could increase the accuracy of individual models. The inclusive multiple model and the comprehensive uncertainty analysis are the innovations of the current study. [ABSTRACT FROM AUTHOR]

The Tethyan metallogenic domain (TMD), as one of the three major domains in the world, extends over 10000 km from east to west, and has developed several world-class metallogenic belts, such as the Gangdese porphyry Cu belt, the Sanjiang metallogenic belt, the Iran porphyry Cu belt, the Pakistan porphyry Cu belt, the southeastern European epithermal gold deposit belt, and the Southeast Asian Sn belt. The formation and evolution of the TMD is mainly controlled by the multi-stage subduction of Tethys oceanic slabs, the opening and closing of several small ocean basins, and continent-continent collision. The Tethys oceans include the Proto-Tethys (Cambrian-Silurian), Paleo-Tethys (Carbonaceous-Triassic) and Neo-Tethys (Jurassic to Cretaceous), which in turn are formed by rifting from the Gondwana land at different times in different micro-continents. With a series of geological processes such as oceanic opening and closing, continental collision and post-collisional reworking with intraplate deformation, various types of ore deposits are developed in the TMD, including porphyry deposits, epithermal deposits, VMS deposits, chromite deposits, Sn deposits and orogenic gold deposits. The metallogenic processes of the TMD can be categorized into three stages. (1) Oceanic subduction: With the subduction of the oceanic slab and dehydration of basalt and sediments, the asthenospheric mantle was metasomatized with preliminary enrichment in metals under oxidized condition. (2) Continental subduction: Continental collision induced partial melting of the mantle wedge enriched the metals and water in mafic melts, which ascended from subarc depths to the lower crust, locally to the shallow crust for hydrothermal mineralization. (3) Post-collisional reworking: Partial melting of the mafic intrusives in the lower crust produced felsic melts under oxidized and water-rich conditions, which underwent crystal fractionation and transferred water and metals into hydrothermal fluids for mineralization. The large-scale porphyry mineralization in the TMD mainly occurs in the Miocene, which is an important scientific issue worthy of further study in the future. How is the metal enriched in the processes of gradual maturity of the crust, and how does large-scale mineralization occur in a collisional orogen where there is no subduction and dehydration of oceanic slabs anymore to supply S and Cl? These are still important questions in the study of porphyry mineralization in the Tethyan orogen. The application of hyperspectral and mineralogical studies of alteration assemblages is beneficial for prospecting and exploration in the TMD. [ABSTRACT FROM AUTHOR]

Copper mineralization in Kahang porphyry mining district as a tectonically active region in the center of Iran, at the middle of Urmia–Dokhtar magmatic assemblage (UDMA), has been drastically controlled by structural lineaments. Determination of these footprint features is a good guide to identify the location of ore occurrences. One way to recognize lineaments is to process satellite imagery along with geophysical data. Although the visual extraction of lineaments from such data set is the most common method, automatic methods for detecting lineaments can highly reduce user errors and runtime. The most efficient automated methods in this regard are those that simultaneously take edge detection filters with lineament extraction algorithms into consideration. In this work, the CANNY algorithm was employed as an edge-detector filter at first and later Hough transform was used to extract linear features from satellite imagery and geophysical magnetometry data. The proposed methods were implemented on the high-resolution imagery data collected by QuickBird satellite along with ground-based magnetometry data to extract the shallow and deep-seated lineaments. After investigating and plotting this structural controller in a map, the dominant orientation was in the NE–SW direction perpendicular to the UDMA. Generated lineament density map also indicated that the eastern, southeast, and western portions of the area had high potential for porphyry copper mineralization. [ABSTRACT FROM AUTHOR]

There are several statistical methodologies presented for separating anomalous values from background leading to determination of anomalous areas. These methods range from simple approaches to complicated ones. A common objective method for anomaly detection in geochemical exploration is target delineation by discriminant function analysis. Discriminant analysis (DA) is a multivariate statistical technique that classifies each observation into a specific group based on observed predictor variables and predefined groups. In the present study, to achieve this target, two populations of anomaly and background were determined using combination of Mahalanobis distance (MD) and median absolute deviation (MAD) method, using borehole data set. For this purpose, in the first step, Mahalanobis distance values should be determined and then MAD method should be applied on Mahalanobis distance values of boreholes data (grade of copper and molybdenum). Thus for separating anomaly from background of surface samples and determining anomaly areas, algorithm of DA method is applied on grade of Cu and Mo (surface samples). Results show that samples indicated by the DA methods as anomalous are more regular; less dispersed and are more accurate than other multivariate methods (e.g., MD method) and other univarite methods since anomalous samples are determined based on several variables. Finally, bivariate lithogeochemical map of the study area is provided for copper and molybdenum which has been prepared using DA method. In this map, the delineated Cu-Mo mineralization is closely associated with the defined zone of potassic alteration, which is also consistent with the field and microscopic observation of the Cu mineralization in this alteration zone. Moreover, it is associated with the phyllic alteration and is spatially conformable with the zone defined for it. [ABSTRACT FROM AUTHOR]

The Davarzan-Abbasabad Eocene Volcanics (DAEV) is located at the northeastern edge of the volcanic-plutonic belt of the Central Iran structural zone. DAEV start with continental to shallow marine sediments of the Paleocene-Eocene and then continue extensively with shallow submarine to sub-aerial basaltic and andesitic volcanics, related volcaniclastics and sedimentary rocks during the Middle-Upper Eocene. The volcanics are olivine basalts, basaltic andesites and andesites in composition and show porphyric, hyaloporphyritic, glomeroporphyric, fluidal, and seriate textures. The geochemistry of DAEV points to a fractional series from olivine basalt to andesite with transitional and medium to high K calc-alkaline nature. Their primitive mantle and chondrite-normalized trace element patterns show that these rocks have high light- and low heavy rare earth elements and are enriched in large-ion lithophile elements and depleted in high field strength elements (Nb, Ti, P, and Zr). Integration of geochemical and petrological data with regional studies indicates that the magma(s) forming the DAEV rocks were derived from 14 to 16 % partial melting of an enriched mantle source in 70-100 km depths during Middle-Upper Eocene time in an intra-arc extensional setting. This mantle source had been previously metasomatized by fluids derived from Sabzevar Neo-Tethyan-subducted slab during the Upper Cretaceous-Paleocene. [ABSTRACT FROM AUTHOR]

This paper presents chemical fractionation and contamination intensities of trace elements in stream sediments at the Sarcheshmeh mine, southeastern Iran, which is one of the world's largest Oligo-Miocene porphyry copper deposits. Evaluation of environmental pollution indices and maximum probable background concentrations revealed that As, Cu, Cd, Mo, Pb, Sb, Se, S, and Zn are highly concentrated in the contaminated sediments, while Cr, Co, Ni, Fe, and Mn show lower enrichment values. Discharges of industrial effluents (especially those contaminated by tailings), reject waste from the semi-autogenous mill, and rock waste drainages are the main anthropogenic contaminant sources. High values of As, Cu, Fe, Mo, Pb, and Zn were associated with the oxidizable, primary sulfide, and residual sediment fractions. Relatively high percentages of Co (>92 %), Cr (>58 %), Cu (>79 %), Fe (>40 %), Mn (>97 %), Ni (>87 %), and Zn (>83 %) in the sediments associated with the rock waste drainages were readily released during the extraction of water-soluble, exchangeable, and carbonate fractions. Sediments that received reject waste drainages were also polluted by As (>351.7 mg kg), Cu (>1.58 %), Mo (>91.8 mg kg), Pb (>291.8 mg kg), and Zn (>762.4 mg kg). A large percentage of these contaminants were found to be adsorbed and co-precipitated with amorphous Fe-oxides and carbonate phases. The chemical fractionation pattern of the potentially hazardous trace elements corresponded well with the mineralogical composition of the contaminated sediments. [ABSTRACT FROM AUTHOR]

Multivariate statistical techniques, i.e., correlation coefficient analysis, principal components analysis (PCA), and hierarchical cluster analysis (CA), were applied to the total and water-soluble concentrations of potentially hazardous metals in sediments associated with the Sarcheshmeh mine, one of the largest Oligo-Miocene porphyry copper deposits in the world. The samples were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method. Results indicate that the contaminant metals As, Cd, Cu, Mo, S, Sb, Sn, Se, Pb, and Zn were positively correlated with the total concentrations. These hazardous metals also have strong association in the PCA and CA results. Different anthropic versus natural sources of contaminant metals were distinguished by using CA method. Water-soluble fraction of hazardous metals showed that the hydro-geochemical behavior of these metals in sediments is different considerably. Elements such as Cd, Co, Cr, Cu, Fe, Mn, Ni, S, and Zn are readily water soluble from contaminated samples, especially from evaporative mineral phases, while the release of As, Mo, Sb, and Pb into the water is limited by adsorption processes. Results obtained from the application of multivariate techniques on the water-soluble fraction data set show that the hazardous metals are categorized into three groups including (1) Ni, S, Co, Cu, Cr, and Fe; (2) Se, Mn, Cd, and Zn; and (3) Sb, As, Mo, and Sn. This classification describes the hydro-geochemical behavior of hazardous metals in water-sediment environments of the Sarcheshmeh porphyry copper mine and can be used as a basis in remedial and treatment strategies. [ABSTRACT FROM AUTHOR]

The Sungun porphyry copper deposit is located 100 km northeast of Tabriz in the Azarbaijan province of Iran. The total concentration and chemical fractionation of metals and metalloids (As, Se, Cd, Cr, Ni, Co, and Zn) in sediment downstream of the Sungun mine was investigated. The degree of contamination was evaluated using the sediment pollution index (SPI) and enrichment factor. The concentrations of As, Cd, Se, and Zn in the contaminated sediments were elevated due to anthropogenic activities. According to the SPI, surface sediments in the ephemeral rivers flowing in the vicinity of the Sungun porphyry copper deposit are classified as natural sediment with no ecological risk, while sediments that received contaminated effluents are classified as slightly polluted. Sequential extraction indicated that Co was principally associated with the iron and manganese oxide fraction, while other elements (As, Zn, Cr, Se, and Ni) were mainly distributed in residual phases. Cadmium is the only element that has a high potential for mobility and bioavailability in the sediments and, of the investigated elements, it poses the greatest potential risk to the local aquatic ecosystems. The chemical fractionation pattern of elements appears to be influenced by industrial effluents. Although the bioavailable fraction of most contaminant metals is low due to the freshness of the sediments, over time, the oxidation of sulfide minerals in these sediments could contribute contaminant elements in soluble form. [ABSTRACT FROM AUTHOR]

Using the analytic hierarchy process (AHP) method for multi-index evaluation has special advantages, while the use of geographic information systems (GIS) is suitable for spatial analysis. Combining AHP with GIS provides an effective approach for studies of mineral potential mapping evaluation. Selection of potential areas for exploration is a complex process in which many diverse criteria are to be considered. In this article, AHP and GIS are used for providing potential maps for Cu porphyry mineralization on the basis of criteria derived from geologic, geochemical, and geophysical, and remote sensing data including alteration and faults. Each criterion was evaluated with the aid of AHP and the result mapped by GIS. This approach allows the use of a mixture of quantitative and qualitative information for decision-making. The results of application in this article provide acceptable outcomes for copper porphyry exploration. [ABSTRACT FROM AUTHOR]

The Sarcheshmeh copper mine smelter plant is one of the biggest copper producers in Iran. Long-time operation of about 25 years of the smelter plant causes release of potentially toxic heavy metals into the environment. In this paper, geochemical distribution of toxic heavy metals in 28 soil samples was evaluated around the Sarcheshmeh smelter plant. Soils developed over the nonmineralized and uncontaminated areas have an average background concentration of 41.25 mg kg Cu, 26.6 mg kg As, 12.7 mg kg Pb, 0.9 mg kg Sb, 1.9 mg kg Mo, 1.7 mg kg Sn, 0.2 mg kg Cd, 0.15 mg kg Bi, 235 mg kg S and 73.4 mg kg Zn, respectively. As a result of smelting process, the upper soil layers (0-5 cm) were polluted by Cu (>1,397 mg kg), Cd (>3.42 mg kg), S (>821 mg kg), Mo (>10.3 mg kg), Sb (>11.7 mg kg), As (>120.6 mg kg), Pb (>83.8 mg kg), Zn (>214.9 mg kg), and Sn (>3.7 mg kg), respectively. These values are much higher than the normal concentration of the elements in the uncontaminated soil layers. The elemental values decrease with distance travelled away of the smelter plant, especially at minimum wind direction. Furthermore, high contaminated values of Cu (8,430 mg kg), As (500 mg kg), Pb (331 mg kg), Mo (61 mg kg), Sb (56.2 mg kg), Zn (664 mg kg), Cd (17.2 mg kg), Bi (13.4 mg kg), and S (3,780 mg kg) were observed in the upper soil layers close to the smelting waste dumps. Sequential extraction analysis shows that about 270 mg kg Cu, 28 mg kg Pb, 50.33 mg kg Zn, and 47.84 mg kg As were adsorbed by Fe and Mn oxides. The carbonate phases include 151 mg kg Cu, 28 mg kg Pb, 25 mg kg Zn, and 32.99 mg kg As. Organic matter adsorbed 314.6 mg kg Cu and 29.18 mg kg Zn. [ABSTRACT FROM AUTHOR]

The Dalli porphyry copper deposit is hosted by the Miocene–Pliocene subvolcanic plutons with chemical composition from diorite to granodiorite that intruded into the andesitic and dacitic volcanic rocks and variety of sedimentary sequences within the Urumieh–Dokhtar Magmatic Arc. Three main hydrothermal alteration zones including potassic, phyllic and propylitic types have been described in the volcano-plutonic rocks. Early hydrothermal alteration started with potassic style in the central part of system produced a secondary biotite–K-feldspar–magnetite assemblage and accompanies to chalcopyrite and pyrite mineralization. This paper summarizes the detailed biotite mineral chemistry from the potassic and phyllic alteration zones. The FeO, TiO2, MnO, K2O, and Na2O (wt.%) concentrations of biotite from the phyllic alteration zone are lower than biotite from the potassic alteration zone. The F and Cl (wt.%) contents of biotite from the potassic alteration zone display relatively high positive correlation with the X Mg. The fluorine intercept values [IV (F)] from the potassic and phyllic alteration zones are strongly positively correlated with the fluorine/chlorine intercept values [IV (F/Cl)]. Biotite geothermometry for the potassic and phyllic alteration zones yield a range from 402° to 450°C and 280° to 343°C, respectively at Dalli porphyry copper deposit. The scatter in log ( X F/ X OH) ratios vs. X Mg and X Fe plots also reflects the evidence of biotite formed under dissimilar composition and temperature conditions in the potassic and phyllic alteration zones. Calculated log fugacity ratios of ( fH2O/ fHF), ( fH2O/ fHCl), and ( fHF/ fHCl) show that hydrothermal fluids associated with the potassic alteration were distinctively different from fluids those associated with the phyllic alteration zone at Dalli porphyry copper deposit. The relation between log ( fH2O/ fHCl) and log ( fH2O/ fHF) fugacity ratios indicates that biotite from the Dalli volcano-plutonic rocks is distinctly similar to biotite from the porphyry copper deposit at Bingham. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study on stream and mine waters in the area of one of the world largest porphyry copper deposit located in the southeastern Iran, the Sar Cheshmeh porphyry copper mine. Trace metals are present as adsorption on Fe and Mn oxide and hydroxide particles, as sulfate, simple metal ions, and scarcely as adsorption on clay particles and hydrous aluminium oxides. Mean pH decreases and the mean concentration of trace elements, EC and $$ SO^{{2 - }}_{4} $$ increases from the maximum discharge period (MXDP) during snow melt run off (May), through the moderate discharge period (MDDP; March and July) to the minimum discharge period (MNDP; September).Water samples have sulfatic character essentially, however, from the MNDP through the MDDP towards the MXDP they show a bicarbonate tendency. This study indicates that the surface waters draining the Sar Cheshmeh open pit have a higher pH and lower concentration of trace metals compared with some other porphyry copper deposits. [ABSTRACT FROM AUTHOR]