Sungun Porphyry Research Articles

Geological domaining at Sungun porphyry copper deposit using cluster analysis

Geometallurgical sampling has an important role in the geometallurgical programme. There are some critical aspects to be considered in geometallurgical sampling. Cluster analysis (CA) is one of the most popular methods that aids in creating domains. This study aims to use CA to create Geological domaining at the Sungun porphyry copper deposit (SPCD). Geological domains of SPCD were defined using PCA and K-means clustering with one hot encoding algorithm. Categorical data were encoded with one hot method and then PCA was used to condense the large new data set to its relevant features. In this research, we have exploited two validity indices to define the optimum number of clusters, namely the silhouette index and the elbow method. Therefore, clustering was performed using four clusters and geological domains were partitioned. The richest domain in this deposit is the second cluster in which the average grades of Cu and Mo are higher than in other clusters. Keywords: Cluster analysis, geological domains, K-means, PCA, Sungun deposit;

Geology and petrogenesis of the Sungun deposits: Implications for the genesis of porphyry-type mineralisation in the NW Urumieh–Dokhtar magmatic Arc, Iran

The Miocene Sungun porphyry Cu–Mo systems, located in Azerbaijan belt, NW Iran, is associated with the high-Sr/Y magmas, which were engendered in a post-collisional setting. However, the petrogenesis of these fertile magmas and their mineralisation are still unknown. In this study, we present whole-rock major-trace elements, zircon U–Pb dating and the Lu–Hf isotopes in the ore-forming porphyries of the Sungun porphyry systems. The corresponding results showed that the samples were rich in large-ion lithophile elements and poor in high-field-strength elements; moreover, they presented both high K2O (2.4–3.5 wt%) and Sr (727–770 ppm) and low Y (11–14 ppm) contents. The zircon U–Pb age of the Sungun porphyry was ~19 Ma, with positive εHf(t) ratios (5.5–11.8) and young TDM2 ages between 322 and 705 Ma. Additionally, the Sungun high-Sr/Y porphyries contained anhydrites (CaSO4); and had high zircon Ce4+/Ce3+ ratios (33–728), relatively low zircon saturation temperatures (620–804 °C), and plagioclases with excess Al content. Overall, these evidences suggest that a water-fluxed melting of the subduction-modified juvenile lower crust might have generated a high oxygen fugacity, leading to the formation of the hydrous and S-rich Sungun fertile magmas in the NW Urumieh–Dokhtar magmatic Arc.

THE MICROWAVE IRRADIATION EFFECT ON THE FLOATABILITY OF MIXED SULPHIDE/OXIDE COPPER ORES

Pre-treatment of copper sulphide and oxide ores using microwave radiation causes a difference in their floatability through change in the surface properties of the minerals. The aim of this study is to investigate the behaviour of Sungun porphyry copper ore under the influence of microwave radiation. In this regard, the feed sample of Sungun copper flotation circuit has been subjected to microwave irradiation for 0-120 s and a radiation power of 0-600 W. The prepared samples were then subjected to flotation experiments. According to the results, the grade of sulphide and oxide Cu minerals, as well as the grade of Fe, increased by microwave irradiation in all experiments compared to the non-irradiated samples. At the same time, recovery rate has a reversed trend and decreased in all cases. Variations in the recovery rates of copper oxides and sulphides due to microwave irradiation are different. Increasing the power of irradiation resulted in a greater reduction in the recovery of copper oxides than of sulphides. On the other hand, increasing the power of microwave irradiation reduced the amount of iron recovery in the copper concentrate and with an increase in the duration of microwave irradiation, the reduction of iron recovery values is even more pronounced. Changes in the power and duration of microwave radiation have not had a significant effect on variations in oxide copper grade in flotation tailings. While the grade of sulphides in tailing is affected by the parameters of microwave irradiation and with an increase in power and duration of microwave irradiation, the grade of copper in tailing increases.

A hybrid approach to model the dykes in Sungun porphyry copper deposit using Dempster–Shafer theory

Modeling geological units such as dykes is a powerful tool in mineral exploration studies. The most significant issue in modeling of uncertainty in the mineral exploration studies is the identification of the geological domains that consist of the zones with significant exploratory factor located in the area under study. The sequential indicator simulation (SIS) algorithm has the ability to model lithological facies. Although the two-point geostatistical simulation approaches are simple, they have some substantial drawbacks. For instance, they do not take into account the complex and nonlinear continuities in geological units like a swarm of the dyke. Therefore, if the area under study has complex geological units, it is necessary to improve the SIS algorithm considering the spatial patterns of complex and nonlinear structures. The pattern recognition method is an effective approach that can improve the two-point geostatistical simulation algorithm. It is based on the informative complex geological spatial patterns that contain the connectivity and nonlinear structures. This paper proposes a hybrid approach (PR-SIS) for simulation of geological units in the presence of several nonlinear structures. To perform hybrid approach, the SIS and pattern recognition methods were used in a combined form. To this end, the results of two methods were combined by the Dempster–Shafer theory (DST) approach. The main purpose of this paper is to investigate the impact of the proposed hybrid approach for modeling the dykes of the Sungun porphyry copper deposit (Iran). To this end, two evidences have been used including the sequential indicator simulation (SIS) method and the pattern recognition approach. These evidences were then applied for using the DST to obtain the final accuracy of the model. Final modeling of this approach shows the continuity of dykes in each location and optimal check with respect to the DST approach based on the geological map. The overall accuracy (OA) and the kappa index (KI) in different dimensions of the search windows showed that the dykes modeling using the hybrid approach by the DST provide a better accuracy. In this regard, the values of OA and KI were 0.889 and 0.792 and 0.901 and 0.805, as well as 0.982 and 0.891 for the SIS method, the pattern recognition method using 2.5 × 2.5 search window, and the proposed hybrid approach by the DST, respectively.

Geometallurgical resource estimation using a modified geostatistical approach; a case study of Sungun porphyry copper deposit, Iran

Geometallurgical modeling involves a comprehensive approach to ore characterization in terms of critical processing attributes, particularly in complex deposits. In this study, an algorithm based on localized uniform conditioning (LUC) method is implemented for creation of spatial geometallurgical domains at Sungun porphyry copper deposit. Localized uniform conditioning (LUC) as a nonlinear method is appropriate for optimal grade estimation of small blocks when the input data spacing is too coarse. In some deposits with complicated geometry, the accuracy of the local estimation through this method depends on the block ranking techniques. The proposed idea is the application of direct block simulation (DBSIM) method realizations for the ranking purpose. The total and oxide copper grades were estimated using the main localized uniform conditioning and proposed algorithm at 30 × 30 × 15 m3 blocks. The outcomes show a satisfactory conformity with the geological facts of the Sungun deposit. Also, the comparison between the results of both methods and the real data confirms the superiority of the proposed method. Finally, the precise destination of each block in the mineral processing circuit has been predicted based on the estimated total and oxide copper grade. The results illustrate that the applied method is able to preserve the spatial variation of attributes and provides an accurate ranking and robust recoverable resource estimation.

Distinctive geochemical features of biotite types from the subeconomic Sonajil porphyry-type Cu deposit, northwestern Iran: Implications for analysis of porphyry copper deposit mineralization potential

The geochemical characteristics of four biotite types comprising 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 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, TiO2, Na2O, SiO2, 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 SO3 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 (ƒO2) 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% SO3 in the biotites of Porphyry stocks. The hydrothermal fluids related to alteration zones in the subeconomic Sonajil have approximately the same range of log(ƒH2O)/(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(ƒH2O)/(ƒHCl) and log(ƒHF)/(ƒHCl) ratios of fluids in equilibrium with biotites alone cannot be a discriminating parameter. Confirmation by SO3 (wt%) content of the biotite types, by linkage between SO3 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 SO3 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.

Characteristics and timing of the Cu–Mo mineralization in the Kighal porphyry stock, NW Iran: Implications for the timing of porphyry Cu-related magmatism in Iran and southern Armenia

The quartz monzonite porphyry stock at Kighal in northwestern Iran intruded the Upper Eocene andesite to latite and basalt units, and the resulted hydrothermal activities led to the development of hydrothermal alteration zones, including potassic, phyllic, argillic and propylitic, coupled with Cu mineralization. Hypogene sulfide mineralization principally occurred within the potassic, transitional potassic–phyllic and phyllic alteration zones as disseminations, stockwork veinlets and open-space fillings. These hypogene minerals include pyrite, chalcopyrite and molybdenite, along with lesser amounts of sphalerite and galena at the marginal parts of the porphyry stock.By taking into account the development of hydrothermal alteration zones and their spatial distribution, stockwork-type mineralization of Cu–Mo minerals, and even the occurrence of mineralization zoning with Cu–Mo-rich ore within the stock and Cu–Pb–Zn ore in the marginal parts, mineralization at Kighal in association with the quartz monzonite sub-volcanic stock can be regarded as of porphyry copper type. However, its low Cu and Mo grade detracts its economic potential.Zircon U–Pb geochronology of the porphyry stock yielded Early Miocene ages of 20.0 ± 0.2 to 18.8 ± 0.2 Ma with a weighted mean of 19.24 ± 0.17 Ma, which correspond to the third porphyry Cu metallogenic epoch in NW Iran. The age data show that it is a little younger than the quartz monzonite porphyry stock in the Sungun porphyry copper deposit (PCD) and the porphyritic granodiorite stock in the Niaz prospect, while it is almost coeval with the porphyritic granodiorite stock in the Haft Cheshmeh PCD, as well as with the mineralization at the Masjed Daghi PCD in NW Iran. The Th/U ratios of the zircons range between 0.37 and 0.59, corresponding to the values for magmatic zircons. The analyzed zircons mainly possess initial εHf(t) values of 6.7 to 10.0, which suggest a juvenile and homogeneous magmatic source and the predominance of mantle-derived magmas with limited crustal assimilation.

Rhenium abundance in molybdenites: a case study on vein-type Cu-Mo-Au mineralisation in the Qarachilar area, Sungun porphyry Cu and Siah Kamar porphyry Mo deposits, NW Iran

The vein-type Cu-Mo-Au mineralisation in Qarachilar, the Sungun porphyry Cu deposit (PCD) and the Siah Kamar porphyry Mo deposit (PMD) are all located at the northwestern end of the Neo Tethys-related Urumieh–Dokhtar volcano-plutonic belt of Iran. Re contents of molybdenite samples from the Qarachilar, Sungun and Siah Kamar deposits are about 112.67–462 ppm, 53.24–252.29 ppm, and 10.44–41.05 ppm, respectively. Re contents of the first two deposits fall in the range of PCDs, while those of the latter are lower and correspond to PMDs. The relatively high Re content of the Qarachilar and Sungun molybdenites can be explained considering the low abundance of molybdenite, a mantle-dominated source for ore materials and the incorporation of oxidized and acidic hydrothermal fluids with high f Cl. The high abundance of molybdenite in the Siah Kamar PMD has resulted in volume dilution of Re. Furthermore, occurrence of the main ore within the potassic alteration zone and, hence, the alkaline nature of the responsible fluids in this zone have also affected the Re content of molybdenites. Variations of the Re content in different veins/veinlets showed a negative relationship with the formation temperature of these veins, and a positive/negative relationship with the acidity/alkalinity of the hydrothermal fluids, while the grain size of molybdenites showed a positive relationship.

Evaluation of Tailings from a Porphyry Copper Mine based on Joint Simulation of Contaminants

Tailings from porphyry copper mines contain environmentally harmful amounts of elements such as copper, molybdenum, lead and cobalt. Geostatistical simulation of contaminants at unknown locations can be helpful in taking preventive measures for tailings management. In the presence of spatially cross-correlated variables, cosimulation has been the traditional method of evaluation. However, application of cosimulation is cumbersome due to modeling so many auto/cross-variograms at once regarding Cauchy–Schwarz inequality. Moreover, cosimulation may face with an unsolvable system of equations in its algorithm. Then, application of joint simulation using minimum/maximum autocorrelation factors which gives reasonable results would be advantageous. In this study, nine spatially cross-correlated attributes of the Sungun porphyry copper deposit are transformed into orthogonal factors. Each factor is independently simulated by generating one hundred equiprobable realizations through the direct sequential simulation or the sequential Gaussian simulation method. The independent simulations are jointly back-transformed into the original data space using a rotation matrix. Test of the final simulations shows reasonable reproduction of data statistics such as the mean and variance values, cumulative distribution functions, cross-correlations and auto/cross-variograms. For each realization, contamination degrees of the blocks are calculated considering the simulated values of variables, the recovery percentage of contaminants in the tailings and the maximum permissible concentrations of the elements in soils. Blocks are categorized regarding the specified contamination degree thresholds and probabilities of occurrence of low, moderate, high and very high contaminations. Sulfide minerals of copper, antimony, arsenic, zinc, molybdenum and silver consist almost 96% of contaminants. All contaminants are sulfide minerals so that additional bulk flotation of the tailings is suggested for reducing their amounts.

Post-Mineralization, Cogenetic Magmatism at the Sungun Cu-Mo Porphyry Deposit (Northwest Iran): Protracted Melting and Extraction in an Arc System

The Sungun porphyry ore deposit is located in Eastern Azarbaijan province, Northwestern Iran. The oldest intrusive pulse in the region is a quartz-monzonite pluton, which hosts the porphyry copper-molybdenum mineralization. The Sungun Copper Mine includes the mineralized Sungun porphyry as well as six groups of cross-cutting and lithologically distinct post-mineralization dykes. The composition of these dykes ranges from quartz diorite, gabbro, diorite, dacite, lamprophyre, and microdiorite. Quartz diorite and dacite dykes are the oldest and youngest dykes, respectively. Based on their cross-cutting relationships, the composition of the dykes tend to become more primitive through time. The dykes strike Northwest–Southeast with Southwest dip, sub-parallel to the reverse faults within the deposit area. The lamprophyric dykes range from phonotephrite, to trachybasalt, tephrite, and basanite. The quartz-monzonite porphyry (SP) and the post-mineralization dykes (DK1-DK3) have clear and distinct negative anomalies of Ti, Zr, P, Pr, Ce, and Nb, as well as positive anomalies of Cs, U, K, Pb, and Nd with respect to primitive mantle. Microdioritic dykes (MDI) show depletion of Ti, Nb, P, Ta, Th, Yb, and Zr, and enrichment of Cs, Ba, U, Pb, Nd. The similarities in trace element abundances and patterns in the porphyry and post-mineralization calc-alkaline dykes implies a single source and fractional crystallization as the main mechanism controlling magmatic evolution in a collisional environment. Lamprophyric dykes have enrichment of LREE and LILE and depletion of HREE and HFSE such as Ti, Nb, and Ta. The parent magma of the lamprophyric dykes (LAM) was likely derived by low degrees of melting of a garnet lherzolite mantle peridotite. The 87Sr/86Sr and 143Nd/144Nd ratios range from 0.704617 to 0.706464 and from 0.512648 to 0.512773 for the dykes suggesting that the parental magmas came from a progressively more enriched mantle. Isotope ratios of 87Sr/86Sr and 143Nd/144Nd support a cogenetic relationship of porphyry and calc-alkaline dykes, except for the microdiorite ones. A common primary melt underwent gravity differentiation in a deep magmatic chamber to form a dioritic magma. This subsequently migrated to shallower levels to evolve further and feed individual dyke groups into the Sungun porphyry.

Comparative study of mineral chemistry of four biotite types as geochemical indicators of mineralized and barren intrusions in the Sungun Porphyry Cu-Mo deposit, northwestern Iran

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 TiO2 (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 TiO2 (4.17 wt% on average). Na2O, SiO2, and MnO (wt%) of biotite are systematically different between mineralized intrusions and barren ones. The highest amounts of Na2O (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% Na2O and 0.03–0.14 wt% MnO. Low SiO2 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 SO3 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 SO3 content of S-Hbt reflect a complex history of formation of S-Hbt in two stages. One group of S-Hbt has SO3 > 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 SO3 < 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 (ƒO2) of 10−15.4–10−13.8 for the mineralized zone of the Sungun Porphyry Cu-Mo deposit lie completely within the domain of logƒO2 > 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.

Application of spectrum-volume fractal modeling for detection of mineralized zones

The main goal of this research work was to detect the different Cu mineralized zones in the Sungun porphyry deposit in NW Iran using the Spectrum-Volume (S-V) fractal modeling based on the sub-surface data for this deposit. This operation was carried out on an estimated Cu block model based on a Fast Fourier Transformation (FFT) using the C++ and MATLAB programing. The S-V log-log plot was generated and six Cu populations were distinguished. Based on the S-V log-log plot obtained, different mineralized zones were detected in the Sungun deposit. Copper mineralized zones in the porphyry and skarn types commenced from 0.12% and 1.3%, respectively. A supergene enrichment zone began form 0.82%; it was located in the eastern part of this deposit. The enriched skarn zones were situated in the eastern and SE parts of the Sungun deposit that overlapped the intersection of cretaceous limestones and porphyry stock. Overlapping between the resulting zones derived via the S-V fractal model and geological zones and evidences were calculated using the logratio matrix, which indicated that the S-V fractal model had proper results for detection of the mineralized zones.

Constraining the timing of porphyry mineralization in northwest Iran in relation to Lesser Caucasus and Central Iran; Re–Os age data for Sungun porphyry Cu–Mo deposit

ABSTRACTThe Neo-Tethyan subduction in Iran is characterized by the Urumieh–Dokhtar magmatic arc (UDMA), formed by northeast-ward subduction of the oceanic crust beneath the central Iran. This belt coincides with the porphyry copper metallogenic belt that comprises several metallogenic zones, including Ahar–Jolfa in northwest Iran. The Ahar–Jolfa metallogenic zone encompasses two main batholiths of Qaradagh and Sheyvardagh and numerous intrusive bodies of Cenozoic, which have produced many base and precious metal deposits and prospects. The former is considered as continuation of the Meghri–Ordubad pluton in South Armenian Block (SAB), which also hosts porphyry copper deposits (PCDs). The Sungun PCD is the largest occurrence in northwest Iran. Rhenium-Osmium ages of Sungun molybdenites are early Miocene and range between 22.9 ± 0.2 and 21.7 ± 0.2 Ma. Comparison of the ages obtained here with published ages for mineralization across the region suggests the following sequence. The earliest porphyry Cu–Mo mineralization event in northwest Iran is represented by Saheb Divan PCD of late Eocene age, which is followed by the second epoch of middle Oligocene, including the Cu–Mo–Au mineralization at Qarachilar and the Haftcheshmeh PCD. Mineralization in Sungun, Masjed Daghi, Kighal and Niaz deposits corresponds to the third mineralization event in northwest Iran. The first epoch in northwest Iran postdates all Eocene mineralizations in SAB, while the second epoch is coeval with Paragachay and the first-stage of Kadjaran PCDs. Its third epoch is younger than all mineralizations in SAB, except the second stage in Kadjaran PCD. Finally, the Cu mineralization epochs in northwest Iran are older than nearly all PCDs and prospects in Central Iran (except the Bondar Hanza PCD), altogether revealing an old to young trend along the UDMA and the porphyry Cu belt towards southeast, resulted from diachronous, later closure of the Neo-Tethyan oceanic basin in central and SE Iran.

Direct block-support simulation of grades in multi-element deposits: application to recoverable mineral resource estimation at Sungun porphyry copper-molybdenum deposit

Direct block-support simulation of grades in multi-element deposits: application to recoverable mineral resource estimation at Sungun porphyry copper-molybdenum deposit

Proposing drilling locations based on the 3D modeling results of fluid inclusion data using the support vector regression method

In recent years, effort has been made to make the results of fluid inclusion studies applicable and use them in the design of the exploration process. It has been tried in this paper to propose a mineralization predictive model for chalcopyrite deposition based on favorable thermodynamic conditions using the 3D modeling results of the fluid inclusion data. To study the applicability and efficiency of the proposed method, Sungun porphyry copper deposit, East Azarbaijan province, Iran, was studied as a case and the 3D model of the fluid inclusion data was prepared using the support vector regression method. The model precisions for the estimation of the fluid inclusion data including homogenization temperature, eutectic temperature and salinity were respectively 76, 71, and 93%. The predictive model was prepared based on the chalcopyrite deposition's favorable thermodynamic conditions (a homogenization temperature range of 300–400°C and moderate-to-high salinity). A comparison of the predictive model with that of the copper grade shows the efficiency of the proposed modeling and high conformity of the two models. The drilling pattern was then investigated based on the predictive model and showed that there would be an almost 6% cost reduction (i.e. elimination of 9 drillholes) if use was made of the proposed predictive model in the design of exploration drillholes.

Risk quantification with combined use of lithological and grade simulations: Application to a porphyry copper deposit

The uncertainty in the recoverable tonnages and grades in a mineral deposit is a key factor in the decision-making process of a mining project. Currently, the most prevalent approach to model the uncertainty in the spatial distribution of mineral grades is to divide the deposit into domains based on geological interpretation and to predict the grades within each domain separately. This approach defines just one interpretation of the geological domain layout and does not offer any measure of the uncertainty in the position of the domain boundaries and in the mineral grades. This uncertainty can be evaluated by use of geostatistical simulation methods. The aim of this study is to evaluate how the simulation of rock type domains and grades affects the resources model of Sungun porphyry copper deposit, northwestern Iran. Specifically, three main rock type domains (porphyry, skarn and late-injected dykes) that control the copper grade distribution are simulated over the region of interest using the plurigaussian model. The copper grades are then simulated in cascade, generating one grade realization for each rock type realization. The simulated grades are finally compared to those obtained using traditional approaches against production data.

Stochastic rock type modeling in a porphyry copper deposit and its application to copper grade evaluation

An accurate definition of geological domains that differentiate the types of mineralogy, alteration and lithology is a critical step in mineral resources and ore reserves evaluation. Deterministic models define just one interpretation of the layout of these domains, based on drill hole data and mining geologist point of view, but do not take into account the uncertainty in areas with fewer data and do not offer any measure of the uncertainty in the domain boundaries. Instead, stochastic models based on geostatistical simulation allow assessing the uncertainty in the spatial layout of the domains. This study addresses the application of plurigaussian simulation in order to simulate the layout of porphyry, skarn and non-mineralized dykes in Sungun porphyry copper deposit (Iran) and to map their probabilities of occurrence over the region of interest. These probabilities are then used for weighting the copper grade prediction associated with each domain so as to obtain the final grade model. Results show the continuity of the grades proper to each domain and across domain boundaries, and compare favorably with respect to the approach based on deterministic geological modeling.

Geostatistical simulation of dyke systems in Sungun porphyry copper deposit, Iran

Post-mineralization activities may cause difficulties in the process of ore modeling in porphyry deposits. Sungun, NW Iran, is one of the porphyry copper deposits, in which dyke intrusions have made ore modeling more complicated than expected. Among different kinds of dykes, two types were chosen and the consequent geostatistical analyses were applied on. In this study, simple directional variograms were used for extracting relevant information from dyke systems on which the Sequential Indicator Simulations were applied consequently. One hundred realizations were produced on the simulation grid considering the anisotropy characteristics and E-type map has been provided averaging all realizations. Moreover, a binary state between dyke and non-dyke environments was produced putting threshold on the E-type grid node values to discriminate the ore from barren dykes. Hole-effect models were fitted to the empirical variograms perpendicular to the dyke strike. Dimensional information was elicited from these models and the results were compared with the previously carried out geological investigations, and finally a good numerical match was found between these two sources of information.

Classification of Alteration Zones Based on Whole-rock Geochemical Data using Support Vector Machine

Abstract One of the most important steps in the mineral resource estimation and detailed exploration of porphyry copper deposit is separating the alteration zones as a control parameter of the copper grade. The most popular method for this separation is petrological investigations (other methods are not much popular), but the method lacks the ability to predict alteration zones of the un-sampled points. In this paper a new method has been proposed which is based on the support vector machine (SVM) classification of the analyzed whole rock samples and it has been used in Sungun porphyry copper deposit to separate potassic, phyllic and transition alteration zones. To apply the SVM method, use has been made of the radial basis function (RBF) as the kernel function and to obtain the optimal values for the SVM parameters (γ and C being the most important); the grid search method has been used. The best values for γ and C that have had good performance in the training and test steps are 0.0625 and 32, respectively. Results have revealed that the SVM classification (used in this study) can effectively separate the alteration zones in the Sungun deposit. Specifically, the accuracy of this method has been 75% which proves that the support vector machine can offer an inexpensive, fast and robust classification technique and it can be a valid alternative to the well established methodologies in this area.

Simulation of geometallurgical variables through stepwise conditional transformation in Sungun copper deposit, Iran

Nowadays, geometallurgical modeling, as a rapidly growing discipline in mining engineering, has significant role in mine designing/planning especially for porphyry copper projects. In porphyry copper deposits, the copper ore often is composed of two main parts including oxide and sulfide ores. The oxide rock type consists a fraction of total copper which would be recovered by heap leaching. Flotation plant is used when the fraction of sulfide ore is high enough. The mineralogical inequality constraint linking both grade variables (total copper and oxide copper) is a difficulty which often complicates the joint modeling and simulation of variables. To simplify such complicated joint simulation, the stepwise conditional transformation technique is presented which transforms multiple variables to the univariate and multivariate Gaussian with no cross correlation. This makes it easy to simulate multiple variables with arbitrarily complex relationships. This study addresses the application of stepwise conditional transformation and sequential Gaussian simulation for reproduction of the total and oxide copper in different rock types of the Sungun porphyry copper deposit honoring the relationship between Cu-oxide and Cu-total of the initial data. Validation results show that the simulation model has a good agreement with the sample data and geological facts of deposit.