Search Results (93)

This study developed a copper mineral prospectivity map for the Koldar massif, Kazakhstan, using an integrated approach combining geophysical and satellite methods. A strong spatialgenetic link was identified between faults and hydrothermal mineralization, with faults acting as key conduits for ore-bearing fluids. Lineament analysis and density mapping confirmed the high permeability of the Koldar massif, indicating its structural prospectivity. Hyperspectral and multispectral data (ASTER, PRISMA, WorldView-3) were applied for detailed mapping of hydrothermal alteration (phyllic, propylitic, argillic zones), which are critical for discovering porphyry copper deposits. In particular, WorldView-3 imagery facilitated the identification of new prospective zones. The transformation of magnetic and gravity data successfully delineated geological features and structural boundaries, confirming the fractured nature of the massif, a key structural factor for mineralization. The resulting map of prospective zones, created by normalizing and integrating four evidential layers (lineament density, PRISMA-derived hydrothermal alteration, magnetic, and gravity anomalies), is thoroughly validated, successfully outlining the known Aktogay, Aidarly, and Kyzylkiya deposits. Furthermore, new, previously underestimated prospective areas were identified. This work fills a significant knowledge gap concerning the Koldar massif, which had not been extensively studied using satellite methods previously. The key advantage of this research lies in its comprehensive approach and the successful application of high-quality hyperspectral imagery for mapping new prospective zones, offering a cost-effective and efficient alternative to traditional ground-based investigations. Full article

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

Copper is typically acknowledged as a critical mineral and one of the vital components of various of today’s fast-growing green technologies. Porphyry copper systems, which are an important source of copper and molybdenum, typically consist of large volumes of hydrothermally altered rocks, mainly around porphyry copper intrusions. Mapping hydrothermal alteration zones associated with porphyry copper systems is one of the most important indicators for copper exploration, especially using advanced satellite remote sensing technology. This paper presents a sophisticated remote sensing-based method that uses ASTER satellite imagery (SWIR bands 4 to 9) to identify hydrothermal alteration zones by combining the discrete wavelet transform (DWT) and the median absolute deviation (MAD) algorithms. All six SWIR bands (bands 4–9) were analyzed independently, and band 9, which showed the most consistent spatial patterns and highest validation accuracy, was selected for final visualization and interpretation. The MAD algorithm is effective in identifying spectral anomalies, and the DWT enables the extraction of features at different scales. The Urmia–Dokhtar magmatic arc in central Iran, which hosts the Zafarghand porphyry copper deposit, was selected as a case study. It is a hydrothermal porphyry copper system with complex alteration patterns that make it a challenging target for copper exploration. After applying atmospheric corrections and normalizing the data, a hybrid algorithm was implemented to classify the alteration zones. The developed classification framework achieved an accuracy of 94.96% for phyllic alteration and 89.65% for propylitic alteration. The combination of MAD and DWT reduced the number of false positives while maintaining high sensitivity. This study demonstrates the high potential of the proposed method as an accurate and generalizable tool for copper exploration, especially in complex and inaccessible geological areas. The proposed framework is also transferable to other porphyry systems worldwide. Full article

The Wubaduolai copper deposit, a newly discovered porphyry-type deposit located in the western section of the Gangdese metallogenic belt, shows great potential for mineralization. Investigating the ore-bearing potentiality of the adakitic granite in this area is crucial for identifying concealed ore bodies and assessing the metallogenic potential. This paper presents the zircon U-Pb dating, Hf isotope analysis, and whole-rock major and trace geochemical analysis of the plutons in the Wubaduolai mining area. The results indicate that the zircon U-Pb concordia age of the monzogranite is 15.7 ± 0.1 Ma, while the granodiorite porphyry has a concordia age of 15.9 ± 0.2 Ma, both corresponding to a Miocene diagenesis. The geochemical data show that both plutons belong to the high-K calc-alkaline series, characterized by a relative enrichment of large-ion lithophile elements (K, Rb, Ba, and Sr) and a depletion of high-field-strength elements (Nb, Ta, and Ti). Both plutons are characterized by low Y, low Yb, and high Sr/Y values, displaying the typical geochemical characteristics of adakites. Their mineral composition is similar to that of adakite. The ε_Hf(t) values of the monzogranite and granodiorite porphyry range from −5.34 to −2.3 and −5.2 to −3.43, respectively, with two-stage model ages (T_DM2) of 1246–1441 Ma and 1318–1432 Ma. Based on the regional data and this study, the plutons in the Wubaduolai mining area formed in a post-collision setting following the India–Asia continental collision. The magma source is identified as the partial melting of a thickened, newly formed lower crust. The above characteristics are consistent with the diagenetic and metallogenic ages, magma source, and dynamic backgrounds of the typical regional deposits. Full article

Unsupervised anomaly detection algorithms have gained significant attention in the field of mineral prospectivity mapping (MPM) due to their ability to reveal hidden mineralization zones by effectively modeling complex, nonlinear relationships between exploration data and mineral deposits. This study utilizes two tree-based anomaly detection algorithms, namely, isolation forest (IF) and extended isolation forest (EIF), to enhance MPM and exploration targeting. According to the conceptual model of porphyry copper deposits, several evidence layers were generated, including fault density, multi-element geochemical signatures, proximity to various alteration types (phyllic, argillic, propylitic, and iron oxide), and proximity to intrusive rocks. These layers were integrated using IF and EIF algorithms, and their results were subsequently compared with a geological map of the study area. The comparison revealed a high degree of overlap between the identified anomalous zones and geological features, such as andesitic rocks, tuffs, rhyolites, pyroclastics, and intrusions. Additionally, quantitative assessments through prediction-area plots validated the efficacy of both models in generating prospective targets. The results highlight the significant influence of hyperparameter tuning on the accuracy of prospectivity models. Furthermore, the study demonstrates that hyperparameter tuning is more intuitive and straightforward in IF, as it provides a clear and distinct tuning pattern, whereas EIF lacks such clarity, complicating the optimization process. Full article

The Kongco area of Nima in the northern part of the Lhasa terrane has a suite of alkaline granitic porphyry dykes associated with Early Cretaceous granites and accompanied by Cu/Mo mineralization. LA-ICP-MS ²⁰⁶Pb/²³⁸U zircon geochronology performed on the dykes produced an age of 104.15 ± 0.94 Ma (MSWD = 0.98), indicating the Early Cretaceous emplacement of the dykes. The dykes exhibit high silica (SiO₂ = 76.22~77.90 wt.%), high potassium (K₂O = 4.97~6.21 wt.%), high alkalinity (K₂O + Na₂O = 8.07~8.98 wt.%), low calcium (CaO = 0.24~0.83 wt.%), low magnesium (MgO = 0.06~0.20 wt.%), and moderate aluminum content (Al₂O₃ = 11.93~12.45 wt.%). The Rieterman index (σ) ranges from 1.93 to 2.34. A/NK (molar ratio Al₂O₃/(Na₂O + K₂O)) and A/CNK (molar ratio Al₂O₃/(CaO + Na₂O + K₂O)) values of the dykes range from 1.06 to 1.18 and 0.98 to 1.09, respectively. The dykes are relatively enriched in Rb, Th, U, K, Ta, Ce, Nd, Zr, Hf, Sm, Y, Yb, and Lu, and they show a noticeable relative depletion in Ba, Nb, Sr, P, Eu, and Ti, as well as an average differentiation index (DI) of 96.42. The dykes also exhibit high FeO_T/MgO ratios (3.60~10.41), Ga/Al ratios (2.22 × 10⁻⁴~3.01 × 10⁻⁴), Y/Nb ratios (1.75~2.40), and Rb/Nb ratios (8.36~20.76). Additionally, they have high whole-rock Zr saturation temperatures (884~914 °C), a pronounced Eu negative anomaly (δEu = 0.04~0.23), and a rightward-sloping “V-shaped” rare earth element pattern. These characteristics suggest that the granitic porphyry dykes can be classified as A2-type granites formed in a post-collisional tectonic environment and that they are weakly peraluminous, high-potassium, and Calc-alkaline basaltic rocks. Positive ε_Hf(t) values = 0.43~3.63 and a relatively young Hf crustal model age (T_DM2 = 826~1005 Ma, ⁸⁷Sr/⁸⁶Sr ratios = 0.7043~0.7064, and ε_Nd(t) = −8.60~−2.95 all indicate lower crust and mantle mixing. The lower crust and mantle mixing model is also supported by (²⁰⁶Pb/²⁰⁴Pb)t = 18.627~18.788, (²⁰⁷Pb/²⁰⁴Pb)t = 15.707~15.719, (²⁰⁸Pb/²⁰⁴Pb)t = 39.038~39.110). Together, the Hf, Sr and Pb isotopic ratios indicate that the Kongco granitic porphyry dykes where derived from juvenile crust formed by the addition of mantle material to the lower crust. From this, we infer that the Kongco granitic porphyry dykes are related to a partial melting of the lower crust induced by subduction slab break-off and asthenospheric upwelling during the collision between the Qiangtang and Lhasa terranes and that they experienced significant fractional crystallization dominated by potassium feldspar and amphibole. These dykes are also accompanied by significant copper mineralization (five samples, copper content 0.2%), suggesting a close relationship between the magmatism associated with these dykes and regional metallogenesis, indicating a high potential for mineral exploration. Full article

Mineral resources, particularly copper, are crucial for the sustained economic growth of developing countries like Kazakhstan. Over the past four decades, the diversity and importance of critical minerals for high technology and environmental applications have increased dramatically. Today, copper is a critical metal due to its importance in electrification. Porphyry deposits are important sources of copper and other critical metals. Conventional exploration methods for mapping alteration zones as indicators of high-potential zones in porphyry deposits are often associated with increased cost, time and environmental concerns. Remote sensing imagery is a cutting-edge technology for the exploration of minerals at low cost and in short timeframes and without environmental damage. Kazakhstan hosts several large porphyry copper deposits, such as Aktogay, Aidarly, Bozshakol and Koksai, and has great potential for the discovery of new resources. However, the potential of these porphyry deposits has not yet been fully discovered using remote sensing technology. In this study, a remote sensing-based mineral exploration approach was developed to delineate hydrothermal alteration zones associated with Aktogay porphyry copper mineralization in eastern Kazakhstan using Landsat-8 and ASTER satellite sensors. A comprehensive suite of image processing techniques was used to analyze the two remote sensing datasets, including specialized band ratios (BRs), principal component analysis (PCA) and the Crosta method. The remote sensing results were validated against field data, including the spatial distribution of geological lineaments and petrographic analysis of the collected rock samples of alteration zones and ore mineralization. The results show that the ASTER data, especially when analyzed with specialized BRs and the Crosta method, effectively identified the main hydrothermal alteration zones, including potassic, propylitic, argillic and iron oxide zones, as indicators of potential zones of ore mineralization. The spatial orientation of these alteration zones with high lineament density supports their association with underlying mineralized zones and the spatial location of high-potential zones. This study highlights the high applicability of the remote sensing-based mineral exploration approach compared to traditional techniques and provides a rapid, cost-effective tool for early-stage exploration of porphyry copper systems in Kazakhstan. The results provide a solid framework for future detailed geological, geochemical and geophysical studies aimed at resource development of the Aktogay porphyry copper mineralization in eastern Kazakhstan. The results of this study underpin the effectiveness of remote sensing data for mineral exploration in geologically complex regions where limited geological information is available and provide a scalable approach for other developing countries worldwide. Full article

The Yidun island arc was formed in response to the Late Triassic westward subduction of the Ganzi–Litang oceanic plate, a branch of the Paleo-Tethys Ocean. The Zhongdian arc, located in the south of the Yidun island arc, has relatively large number of porphyry (skarn) type Cu–Mo ± Au polymetallic deposits, the largest of which is the Pulang Cu (–Mo–Au) deposit with proven Cu reserves of 5.11 Mt, Au reserves of 113 t, and 0.17 Mt of molybdenum. However, the relationship between mineralization and the potassic alteration zone, phyllic zone, and propylitic zone of the Pulang porphyry deposit is still controversial and needs further study. Titanite (CaTiSiO₅) is a common accessory mineral in acidic, intermediate, and alkaline igneous rocks. It is widely developed in various types of metamorphic rocks, hydrothermally altered rocks, and a few sedimentary rocks. It is a dominant Mo-bearing phase in igneous rocks and contains abundant rare earth elements and high-field-strength elements. As an effective geochronometer, thermobarometer, oxybarometer, and metallogenic potential indicator mineral, titanite is ideal to reveal the magmatic–hydrothermal evolution and the mechanism of metal enrichment and precipitation. In this paper, major and trace element contents of the titanite grains from different alteration zones were obtained using electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to define the changes in physicochemical conditions and the behavior of these elements during the process of hydrothermal alteration at Pulang. Titanite in the potassic alteration zone is usually shaped like an envelope. It occurs discretely or is enclosed by feldspar, with lower contents of CaO, Al, Sr, Zr and Hf; a low Nb/Ta ratio; high ∑REE + Y, U, Th, Ta, Nb, and Ga content; and high FeO/Al₂O₃ and LREE/HREE ratios. This is consistent with the characteristics of magmatic titanite from fresh quartz monzonite porphyry in Pulang and other porphyry Cu deposits. Titanite in the potassium silicate alteration zone has more negative Eu anomaly and a higher U content and Th/U ratio, indicating that the oxygen fugacity decreased during the transformation to phyllic alteration and propylitic alteration in Pulang. High oxygen fugacity is favorable for the enrichment of copper, gold, and other metallogenic elements. Therefore, the enrichment of copper is more closely related to the potassium silicate alteration. The molybdenum content of titanite in the potassium silicate alteration zone is 10²–10⁴ times that of the phyllic alteration zone and propylitic alteration zone, while the copper content is indistinctive, indicating that molybdenum was dissolved into the fluid or deposited in the form of sulfide before the medium- to low-temperature hydrothermal alteration, which may lead to the further separation and deposition of copper and molybdenum. Full article

The Luang Prabang (Laos)–Loei (Thailand) metallogenic belt is located on the northwestern margin of the Indochina Block. It is one of the most important gold–copper metallogenic belts in Southeast Asia. This region underwent tectonic and magmatic evolution in the late Paleozoic-Mesozoic period within the Paleo-Tethys realm, resulting in complex metallogenic processes. Consequently, epithermal Au-Ag, porphyry-skarn Au-Cu, and hydrothermal vein-type gold deposits were formed. However, the genetic type of the vein-type gold deposits is still not fully understood. The relationship between the three types of gold deposits and the regional tectonic evolution has not been summarized up until today. We summarize the previous mineralization characteristics and exploration data of commonly known deposits and combine them with new evidence and ore deposit insights from our recent studies on the source and evolution of ore-forming fluids in the region. We confirm that the hydrothermal vein-type gold deposits in the belt are typical orogenic gold deposits. Based on previous regional tectonic-magmatic-metallogenic studies, metallogenic characteristics, and temporal and spatial distribution of three types of typical gold–copper deposits in the belt, we synthesize and establish a regional metallogenic model related to the subduction-closure of the Paleo-Tethys Ocean and subsequent continental–continental collision process, resulting in the formation of epithermal Au-Ag during the late Permian-early Triassic subduction, porphyry-skarn Au-Cu in the early–middle Triassic period during the closure of the ocean, and orogenic Au during the late Triassic collision. Since there are few reports on the geochemical characteristics of gold–copper deposits and their related magmatic rocks, the potential for gold–copper mineralization and their links to the magmatic rocks in the belt still needs further study. Full article

In this study, an innovative methodology using trivariate copula-based conditional quantile regression (CBQR) is proposed for estimating copper recovery. This approach is compared with six supervised machine learning regression methods, namely, Decision Tree, Extra Tree, Support Vector Regression (linear and epsilon), Multilayer Perceptron, and Random Forest. For comparison purposes, an open access database representative of a porphyry copper deposit is used. The database contains geochemical information on minerals, mineral zoning data, and metallurgical test results related to copper recovery by flotation. To simulate a high undersampling scenario, only 5% of the copper recovery information was used for training and validation, while the remaining 95% was used for prediction, applying in all these stages error metrics, such as R², MaxRE, MAE, MSE, MedAE, and MAPE. The results demonstrate that trivariate CBQR outperforms machine learning methods in accuracy and flexibility, offering a robust alternative solution to model complex relationships between variables under limited data conditions. This approach not only avoids the need for intensive tuning of multiple hyperparameters, but also effectively addresses estimation challenges in scenarios where traditional methods are insufficient. Finally, the feasibility of applying this methodology to different data scales is evaluated, integrating the error associated with the change in scale as an inherent part of the estimation of conditioning variables in the geostatistical context. Full article

The work focuses on five epithermal Au-Ag deposits of the Kamchatka volcanogenic belts: Rodnikovoe, Baranyevskoe, Kumroch, Lazurnoe (adularia-sericite type–Ad-Ser) and Maletoyvayam (acid-sulfate type–Ac-Sul). The geochemical characteristics of the deposits were presented based on the results of ICP-OES and fire-assay analysis. The compositions and physicochemical parameters of ore-forming fluids were based on microthermometry, Raman spectroscopy and gas chromatography-mass spectrometry. It was shown that all deposits were comparable in terms of temperatures, salinity and the predominance of H₂O and CO₂ in ore-forming fluids. The deposits were formed at temperatures of 160–308 °C by aqueous fluids with salinities of 0.5–6.8 wt. % (NaCl-eq.). The Maletoyvayam deposit differed from the other ones in significant enrichment in Se, Te, Sb, Bi and As, as well as much higher concentrations of hydrocarbons, nitrogenated and sulfonated compounds (31.4 rel.% in total) in the composition of fluid inclusions. This gave us a reason to assume that organic compounds favourably affected the concentrations of these elements in the mineralising fluid. Kumroch and Lazurnoe were distinguished from Rodnikovoe and Baranyevskoe by high Zn, Pb and Cu contents, where each of them represented a single system combining both Ad-Ser type epithermal gold-silver and copper porphyry mineralisations. The presence of alkanes, esters, ketones, carboxylic acids and aldehydes in different quantities at all deposits were indicators of the combination of biogenic and thermogenic origins of organic compounds. The contents of ore-forming elements in ores were consistent with the specificity of mineral assemblages in the Kamchatka deposits. Full article

Magnetic and electromagnetic techniques have a long history of application in mineral exploration to detect deposits and their surroundings. Their implementation over the last fifteen years has been affected by strong variations in the mining market in parallel with important technological developments. During this period, both methods were the subject of numerous documented case studies all over the globe, which is a sign of popularity and longevity of these techniques. Through a review of case histories from the main geophysical journals, we analyze the principal usage of these methods when applied to mineral exploration, while the majority of documented cases originate from North America, Asia, and Australia. There are more case studies describing the use of the magnetic method and we attribute this popularity to direct and indirect use of this method for mineral exploration. In particular, there is an increasing number of magnetic surveys conducted with drones. Combining magnetic and electromagnetic techniques is also common. The number of magnetic and EM technique case histories range by descending order from gold, porphyry copper, polymetallic, massive sulfides, uranium, Ni-Cu-PGE, iron ore, kimberlite, and iron-oxide copper-gold, with a number of single continent-specific applications. Full article

The 1500 km-long Gangdese magmatic belt is a crucial region for copper polymetallic mineralization, offering valuable insights into collisional porphyry copper systems. This study focuses on the Demingding deposit, a newly identified occurrence of molybdenum–copper (Mo-Cu) mineralization within the eastern segment of the belt. While the mineralization age, magmatic characteristics, and tectonic context are still under investigation, we examine the deposit’s petrology, zircon U-Pb geochronology, whole-rock chemistry, and Re-Os isotopic data. The Demingding deposit exhibits a typical alteration zoning, transitioning from an inner potassic zone to an outer propylitic zone, which is significantly overprinted by phyllic alteration closely associated with Mo and Cu mineralization. Zircon U-Pb dating of the ore-forming monzogranite porphyries reveals crystallization ages ranging from 21 to 19 Ma, which is indistinguishable within error from the mean Re-Os age of 21.3 ± 0.4 Ma for Mo veins and veinlets hosted by these porphyries. This alignment suggests a late Miocene magmatic event characterized by Mo-dominated mineralization, coinciding with the continuous thickening of the continental crust during the collision of the Indian and Asian continents. The ore-forming porphyries range in composition from granodiorite to monzogranite and are classified as high-K calc-alkaline with adakite-like features, primarily resulting from the partial melting of subduction-modified thickened mafic lower crust. Notably, the ore-forming porphyries exhibit higher fO₂ and H₂O levels than barren porphyries in this area during crustal thickening, highlighting the significant contributions of hydrous and oxidized fluids from their source to the Mo-Cu mineralization process. Regional data indicate that the Gangdese porphyry metallogenic belt experienced concentrated Cu-Mo mineralization between 17 and 13 Ma. The formation of Mo-dominated deposits such as Demingding and Tangbula in the eastern segment of the belt, with slightly older ages around 20 Ma, underscores the presence of a significant porphyry Mo metallogenic event during this critical post-collision mineralization period. Full article

An association of bismuth sulfosalts coexisting with native gold is described from a sulfide-rich copper vein in the Nistru area, Baia Mare metallogenetic district, NW Romania. This mineralization is hosted within a Neogene calc-alkaline subvolcanic porphyry quartz-micromonzodiorite stock on the southern border of the Gutâi Mountains. Cu+Au+Bi mineralization represents the inner part of a zoned vein of a type specific to the SE part of the Nistru orefield. The Pb-Zn and Au-Ag veins are located towards the external zone at the boundary of the stock with the surrounding rocks. Bismuth sulfosalts are mainly represented by bismuthinite derivatives and members of the lillianite homologous series. Cosalite, matildite and wittichenite are also present in subordinate amounts. Bi-rich members of the bismuthinite-aikinite series (from krupkaite to bismuthinite) are predominant. A phase with the empirical formula CuPbBi₇S₁₂ was also identified and could potentially be a new bismuthinite derivative. The lillianite homologous series is represented by phases with composition between Gus₇₃ and Gus₅₉, with a dominance of members closer to gustavite (Gus_97–79) and less abundant members closer to lillianite (Gus₄₉). Native gold and Bi-sulfosalts are closely associated with the main sulfides (pyrrhotite, pyrite, chalcopyrite) and quartz, indicating simultaneous crystallization. Fluid inclusion data for quartz indicate a temperature interval between 205 and 247 °C. The assemblage within this vein was deposited from a low-salinity fluid (0.4–2.6 wt.% NaCl equiv.) and density from 0.80 to 0.87 g/cm³. Full article

The Alattu–Päkylä gold occurrence is located in the Northern Lake Ladoga area, in the Raaha-Ladoga suprasubduction zone, at the Karelian Craton (AR)—Svecofennian foldbelt (PR₁) boundary. Its gold ore mineral associations are of two types of mineralization: (1) copper–molybdenum–porphyry with arsenopyrite and gold (intrusion-related) and (2) gold–arsenopyrite–sulfide in shear zones. Optical and scanning electron microscopy, X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA) and fire analysis with AAS finishing were used to study them. Type 1 was provoked by shallow-depth tonalite intrusion (~1.89 Ga) and type 2 by two stages of Svecofennian metamorphism (1.89–1.86 and 1.83–1.79 Ga) with the possible influence of the impactogenesis of the Janisjärvi astrobleme (age ~1 Ga). Intrusive and host rocks were subjected to shearing accompanied by the formation of ore-bearing metasomatic rocks of the propylite-beresite series (depending on substrate) and quartz–sericite, quartz and sericite–tourmaline veins and streaks. Ore mineralization is present as several consecutive mineral associations: pyritic–molybdenite with arsenopyrite and gold; gold–arsenopyrite; quartz–arsenopyrite with antimony sulfosalts of lead; gold–polysulfide with tetrahedrite –argentotetrahedrite series minerals and gold–antimony with Pb–Sb–S system minerals and native antimony. Arsenopyrite contains invisible (up to 234 ppm) and visible gold. Metamorphosed domains in arsenopyrite and rims with visible gold around it are usually enriched in As, indicating higher (up to >500 °C) temperatures of formations than original arsenopyrite with invisible gold (<500 °C). A paragenetic sequence associated with the deposition of invisible and visible gold established at the Alattu–Päkylä ore occurrence: pyrrhotite + unaltered arsenopyrite (with invisible gold) → altered arsenopyrite (As-enriched) + pyrite ± pyrrhotite + visible gold. Gold, associated with gudmundite, sphalerite and native antimony, seems to be due to cainotypic rhyodacitic porphyry cutting tonalite intrusion or with a retrograde stage in post-Svecofennian metamorphism. The isotopic composition of Pb and ²³⁸U/²⁰⁴Pb (9.4–9.75) for the feldspar of the tonalite intrusion and the pyrite of gold mineralization, εNd (−4 up to −5) for tonalites and ẟ³⁴S values of −2.10–+4.99 for arsenopyrite, indicate the formation of gold occurrence provoked by Svecofennian magmatic and tectono-thermal processes with the involvement of matter from a mantle-lower crustal reservoir into magma formation and mineralization. Full article