Search Results (31)

The economic importance of Carlin-type gold deposits is complicated by the concealed nature of stratiform gold-bearing zones and their occurrence at depths of several tens of meters or more below the present-day surface. This necessitates the use of a wide range of technologies and unconventional, including cost-effective and environmentally friendly, exploration methods to delineate potentially prospective areas. This study explores the possibilities of applying remote sensing methods to organize prospecting and exploration activities for targeting Carlin-type deposits in a more efficient and cost-effective way. The location of Carlin-type gold deposits within areas of orogenic and post-orogenic magmatism, mantle plumes, and linear crustal structures—as demonstrated by previous research in the Nevada and South China metallogenic provinces—may serve as a basis for developing a conceptual model of their distribution. To this end, we developed the GeoNEM (Geodynamic Numeric Environmental Modeling) software in Python, which enables the analysis of the formation of fold and fault structures, melt emplacement and contamination, as well as the duration and rate of geodynamic processes. GeoNEM is based on the computational geodynamics “marker-in-cell” (MIC) method, which treats geological media as extremely high-viscosity fluids. Locations of the brittle deformations of the crust, the formation of which was simulated numerically, can be detected through lineament analysis of remote sensing images. The spatial distribution of such structures—lineaments—serves as a predictive criterion for assessing the prospectivity of territories for Carlin-type gold deposits. It has been demonstrated that remote sensing provides a modern level of efficiency, cost-effectiveness, and comprehensiveness in approaching the exploration and assessment of new Carlin-type gold deposits. This is particularly important in the context of rational resource utilization and cost reduction. Full article

Sb-rich avicennite (first discovery in Russia) was found at the Khokhoy gold deposit, 120 km west of Aldan, Aldan district, Republic of Sakha (Yakutia), Eastern Siberia, Russia. The mineral of critical metal thallium forms irregularly shaped grains up to 0.25 mm in size, in association with amgaite, weissbergite, goethite, gold, and unidentified Tl-bearing phases. Aggregates of colloform structure prevail, represented by rhythmic-, concentric-zonal, kidney-shaped, and spherulitic varieties. Avicennite is black in color, with metallic luster, and it fractures unevenly. No cleavage is observed. The density value of avicennite, obtained using its empirical formula and the unit cell parameters calculated from the powder X-ray diffraction data, is 8.548 g/cm³. In reflected light, avicennite is light gray and isotropic. Internal reflections are absent. Reflection is very low; the reflectivity curve is of mixed type with a small maximum in the blue part. Its chemical composition (average value on 10 analyses, wt.%): Tl₂O₃—85.36, V₂O₅—0.73, As₂O₅—0.85, Sb₂O₅—12.98, Total—99.92; It corresponds to the following empirical formula (calculation for three atoms of O): Tl_1.40Sb⁵⁺_0.30V⁵⁺_0.03As⁵⁺_0.03O₃. The unit cell parameters calculated from the powder X-ray diffraction data are as follows: the mineral is cubic, a = 10.496(6) Å, V = 1156(2) Å3. Full article

In many gold–antimony deposits throughout the world, the sequence of Au and Sb precipitation varies significantly. In high-temperature systems such as hydrothermal Au deposits, gold typically precipitates prior to antimony, whereas in lower-temperature systems (e.g., Carlin-type deposits), no consistent depositional sequence is observed. The Gutaishan Au-Sb deposit, located in the Xiangzhong Basin of the Jiangnan Orogenic Belt, South China, exhibits a distinct spatial segregation within a continuously evolving system of gold and antimony mineralization—a pattern commonly observed in many Au-Sb deposits throughout the region. To elucidate the mechanisms controlling Au-Sb co-occurrence and segregation, we conducted electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) major and trace element analyses of stibnite and pyrite from quartz veins across different ore zones within the Gutaishan deposit. Trace element signatures—such as Cu-Pb correlations and Hg/(Cu + Pb) ratios which classify stibnite into Woxi-type and Xikuangshan-type, and Co/Ni ratios classifies pyrite into magmatic–hydrothermal and sedimentary types—suggest that the ore-forming fluids were predominantly magmatic–hydrothermal in origin, with minor contributions from metamorphic basement fluids. The occurrence of low-temperature trace element signatures in the Au-Sb deposit indicates that temperature is the primary control on Au-Sb segregation. The thermodynamic model further confirms that high-temperature fluids favored the precipitation of Au veins, while lower-temperature fluids facilitated the co-precipitation of stibnite and gold in Sb-Au veins. Therefore, we propose a metallogenic model for the Gutaishan deposit that highlights temperature-driven Au-Sb segregation, resulting from the progressive cooling of the ore-forming fluids. Full article

Carlin-type gold deposits in southwestern Guizhou, China require systematic exploration methods to identify deep and peripheral prospecting potential beyond known deposits. We conducted a 1:50,000-scale soil geochemical survey across 928 km² in the Nibao gold deposit and its surrounding areas, with a total of 8842 samples collected. Fifteen elements were systematically analyzed, with particular focus on pathfinder elements associated with Carlin-type gold mineralization. Building on previous comparative analyses of soil geochemical and tectono-geochemical characteristics, this research systematically examines the enrichment patterns of soil geochemistry and their significance for ore prospecting. The results demonstrate that (1) elements such as Au, As, Sb, Hg, W, and Mo show significant positive correlation and strong enrichment patterns, indicating excellent metallogenic potential; (2) 176 and 12 single- and composite-element anomalies were delineated, respectively, with HS-2, HS-3, and HS-7 anomalies exhibiting high intensity and distinct concentration zonation, similar to those of the high factor score distribution of Au-As-Sb-Hg-W-Mo; (3) three prospecting targets were identified based on anomaly characteristics and geological conditions, including Nibao, Baogudi, and Sandaogou; (4) multiple mineralized bodies were revealed through engineering verification, indicating good prospecting potential in the deep and surrounding areas of the targets. These findings provide a scientific basis for further exploration of Carlin-type gold deposits in the study area and southwestern Guizhou. Full article

Gold is a vital strategic resource for many countries. The Laozhaiwan area is an important gold resource base in Yunnan Province and even nationwide. Conducting mineral resource exploration in this region to increase gold reserves is of great significance. The application of remote sensing technology in mineral resource exploration is a green and efficient technical approach, which has been widely utilized in the field of mineral resource prospecting. This study selects the Laozhaiwan area in the southeastern part of Yunnan Province as the research region. Linear and ring structures were extracted using the remote sensing visual interpretation method based on Sentinel-2A multispectral data. Additionally, Sentinel-2A, ASTER, and ZY1-02D data were used to extract iron-stained, hydroxyl, silicification, and limonite alteration information through Principal Component Analysis (PCA) and Spectral Angle Mapper (SAM) methods. Additionally, 50 linear structures and 12 ring structures were extracted. A comprehensive analysis of geological data reveals that alteration minerals and linear-ring structures are closely related to mineralization, providing valuable indicators for mineral resource exploration. By comprehensively analyzing the alteration information and remote sensing interpretation results of the linear-ring structures, two prospective areas for mineral exploration were delineated. Field investigations and petrographic studies confirmed the reliability of remote sensing technology in mineral exploration. The mineral exploration method based on multi-source remote sensing technology can clearly reflect various alteration information and linear-ring structural data. It provides remote sensing geological insights for geological survey work and has great application potential in the field of mineral resource exploration. Full article

Eocene magmatic systems contemporaneous with world-class Carlin-type Au deposits in Nevada (USA) have been proposed by some researchers as a key ingredient for Au mineralization, though evidence conclusively demonstrating their genetic relationship remains tenuous. This study provides the first direct evidence of the pre-eruptive metal budget of volatile- and metal-charged silicic magmas coincident in time (~41 to 34 Ma) and space (within 5 km) with Carlin-type Au deposits. We characterize the pre-eruptive metal fingerprints of these diverse magmatic systems to assess their potential as sources of metals for Carlin-type Au mineralization. Metal abundances from quartz-hosted melt inclusions (Au, Te, Ag, Sb, Tl, Mo, W, Sn, As, Pb, Co, Cu, Ni, and Zn) characterized in situ by SHRIMP-RG and LA-ICP-MS represent our best (and only) estimates for the pre-eruptive metal budget in these systems. Median metal concentrations are generally within one order of magnitude of average upper crust and average continental rhyolite values. But there are two notable exceptions, with median Au contents extending >1 order of magnitude higher than average upper crust and median Cu contents ranging >1 order of magnitude lower than upper crust. Despite this, melts contain lower Au/Cu (<0.1), Au/Ag (<5), and Au/Tl (<0.3) than most ore-grade Carlin-type rock samples and quartz-hosted fluid inclusions, regardless of their age and timing relative to nearby Carlin-type Au mineralization. The metal fingerprints of these magmatic systems, defined both by traditional and multivariate compositional data analysis techniques, are distinct from one another. Yet none are particularly specialized, e.g., high Au/Cu, in terms of being ideal ingredients as postulated by magmatic models for Carlin-type Au mineralization. Magmatic Au contents do not appear to be correlated with rhyolite “flavors” in the way that Cu, Sn, and Nb contents are. Fluid/melt partitioning modeling and magma volume estimates support the idea that a diverse array of non-specialized silicic magmas could feasibly contribute some or potentially all of the Au, Ag, and Cu in Carlin-type systems. The compositional diversity among contemporaneous magmatic systems could possibly contribute to some of the diversity observed across Carlin-type Au districts in Nevada. Full article

Previous research on Carlin-type gold deposits in North America and China has revealed peculiarities in their genesis, distribution, and prospectivity. However, pinpointing these deposits within known ore districts and prospective areas is a complex and resource-demanding task. Studying the structural and geological characteristics of Carlin-type deposits in areas with a longer history of exploration using machine learning techniques is crucial, especially considering the potential for discovering Carlin-type deposits in Russia. Crustal fracturing fields detected in space imagery and digital relief models can serve as a foundation for prospectivity mapping of Carlin-type deposits, even without evidence of magmatic sources of ore matter. The detection of disjunctive features, observed as linear elements (lineaments) in remote sensing images of the Earth, allows for a quantitative description of the Earth’s crust permeability to ore-bearing magmas and fluids. This can be accomplished using open source pyLEFA software. Optical detection methods facilitate this process, while the assessment of heterogeneity in the distribution of fracture field parameters is achieved using unsupervised learning and classification. Machine learning based on datasets produced with pyLEFA enables the assessment of the contribution of predictor variables to the result. The knowledge acquired can be applied to areas with the potential for discovering Carlin-type deposits. Full article

Geochemical data serve as crucial references for prospecting, and the effective extraction of prospecting information from such data determines the success rate of exploration. In the era of big data, novel prospecting methods based on geochemical data offer new ideas for exploring various ore deposits. By employing advanced data analysis techniques like machine learning and artificial intelligence, it becomes possible to identify elusive patterns and trends that are challenging to detect using traditional approaches, thereby significantly enhancing the success rate of prospecting endeavors. In this study, we selected drainage sediment geochemical data (Au, Ba, Mo, Sb, V, W, Zn) in the Jinya-Mingshan area to explore potential Carlin-type gold deposits. Traditional geochemical processing methods along with an association rule algorithm were employed for conducting comprehensive data mining analysis. The results demonstrate that the element combinations within the study area can be categorized into strong positive associations and enrichments (Mo, Sb, Zn) associated with vulcanization, strong negative associations, and decarbonation-related migration elements (Ba), as well as strong positive associations and weakly enriched elements (W) and weak positive associations and weakly enriched elements (V) not significantly related to mineralization. In comparison to Mo and Sb, which are closely linked to Au as revealed by cluster analysis and factor analysis, the association rule algorithm also reveals a relatively close correlation between Ba, Zn, and Au. Based on the element correlations obtained through the association rule algorithm, a new prospecting index was constructed for the study area. This new index is more reasonable than traditional indices. In conclusion, the association rule algorithm possesses unique advantages in information mining of geochemical data and holds promising applications in geological exploration. Full article

The Youjiang metallogenic province (YMP) is a famous ore-concentrating area in South China, known for its substantial Carlin-type gold deposits, antimony deposits, and mercury deposits. Previous studies have yielded conflicting views regarding the ages of mineralization in this area, particularly regarding the occurrence of Yanshanian versus Indosinian ore-forming events during the Mesozoic era. To resolve these discrepancies, this study utilized in situ LA-ICP-MS U-Pb dating on carbonate minerals from the Lannigou Carlin-type Au deposit, the Lanmuchang Hg-(Tl) deposit, and the Sixiangchang Hg deposit to accurately determine their mineralization ages. Our results indicate that the three deposits formed at 137 ± 9 Ma, ~97 Ma, and 454 ± 21 Ma, respectively. By integrating previously reported geochronological data, we propose that the low-temperature Au-As-Sb-Hg-Tl deposits in the YMP were formed during two major periods, Late Triassic and Late Jurassic to Cretaceous, with the latter being more prevalent. Additionally, there was a Paleozoic hydrothermal mercury mineralization event at the northeastern edge of this region. These newly acquired data significantly enhance our understanding of multistage, low-temperature mineralization events in the YMP. Our study also demonstrates that in situ carbonate U-Pb dating is an excellent method for investigating the timing of low-temperature mineralization events. Full article

This study focuses on exploring the indication and importance of selenium (Se) and tellurium (Te) in distinguishing different genetic types of ore deposits. Traditional views suggest that dispersed elements are unable to form independent deposits, but are hosted within deposits of other elements as associated elements. Based on this, the study collected trace elemental data of pyrite, sphalerite, and chalcopyrite in various types of Se-Te bearing deposits. The optimal end-elements for distinguishing different genetic type deposits were recognized by principal component analysis (PCA) and the silhouette coefficient method, and discriminant diagrams were drawn. However, support vector machine (SVM) calculation of the decision boundary shows low accuracy, revealing the limitations in binary discriminant visualization for ore deposit type discrimination. Consequently, two machine learning algorithms, random forest (RF) and SVM, were used to construct ore genetic type classification models on the basis of trace elemental data for the three types of metal sulfides. The results indicate that the RF classification model for pyrite exhibits the best performance, achieving an accuracy of 94.5% and avoiding overfitting errors. In detail, according to the feature importance analysis, Se exhibits higher Shapley Additive Explanations (SHAP) values in volcanogenic massive sulfide (VMS) and epithermal deposits, especially the latter, where Se is the most crucial distinguishing element. By comparison, Te shows a significant contribution to distinguishing Carlin-type deposits. Conversely, in porphyry- and skarn-type deposits, the contributions of Se and Te were relatively lower. In conclusion, the application of machine learning methods provides a novel approach for ore genetic type classification and discrimination research, enabling more accurate identification of ore genetic types and contributing to the exploration and development of mineral resources. Full article

The La’erma and Qiongmo Au–Se deposits are characterized by a paragenetic Au–Se association hosted in the siliceous formation of the Cambrian Taiyangding Group in the western Qinling Orogen, central China. The La’erma and Qiongmo Au–Se deposits, which are considered to be the Carlin gold deposits, comprise a variety of selenides, native gold, and stibnite coexisting with baryte. Four stages have been recognized: sage I comprises pyrite and quartz with minor stibnite; stage II is composed mainly of sulfides; stage III is composed mainly of selenides; and stage IV is dominated by quartz–baryte–dickite. Stages II and III are the main metallogenic stages. Based on changes in mineral assemblages, combined with fluid inclusions and thermodynamic data, we evaluated the physicochemical conditions of the main metallogenic stages. The logfS₂ values of ore-forming fluids at stage II ranged between −10.44 and −14.60 with logfSe₂ being less than −10.70. Comparably, during stage III, which is characterized by numerous selenides, the logfS₂ and logfSe₂ ranged from −7.13 to −12.20 and −13.98 to −8.82, respectively. The occurrence of baryte during the mineralization suggests a consistently oxidizing condition, which can effectively remove Au from fluids. More importantly, this study emphasizes that the oxidizing condition was only a fundamental prerequisite for the deposition of selenides, and a high ∑Se/S ratio of the fluid ultimately controlled the precipitation of selenides. In the La’erma and Qiongmo deposits, intense water–rock reactions occurred as ore-forming fluids flowed into the Se-rich siliceous formations, resulting in an increase in the ∑Se/S ratio of the fluid and in the precipitation of selenides. Full article

The Youjiang Basin in China is the world’s second-largest concentrated area of Carlin-type Au deposits after Nevada, USA, boasting cumulative Au reserves nearing 1000 t. This study examined the recently unearthed Lintan Carlin-type Au deposit within the Youjiang Basin. Factor analysis and association rule algorithms were used to identify exploration vectors and indicators essential for navigating this promising geological territory. In the Lintan mining area, the geological strata encompass the Triassic Bianyang, Niluo, and Xuman formations comprised clastic rocks, followed by the deeper Permian Wujiaping Formation with massive carbonate rocks. The orebodies are restricted to the F₁₄ inverse fault, cutting through the Xuman Formation, with an additional F₇ fault between the Wujiaping and Xuman formations. A total of 125 rock samples from the F₁₄ fault and a representative cross-section were analyzed for 15 elements (Au, Ag, As, Bi, Cd, Co, Cu, Hg, Mo, Ni, Pb, Sb, Tl, W, and Zn). The elements were divided into four groups based on cluster and factor analysis. Group 1 (Co, Cu, Zn, Ni, Tl, W, and Bi) was mainly enriched in the Xuman, Niluo, and Bianyang formations controlled by sedimentary diagenesis. Group 2 (Au, As, Hg, and Sb) was concentrated in the F₁₄ and F₇ faults, representing Au mineralization. Group 3 (Pb, Ag, and Mo) was mostly enriched near the F₁₄ and F₇ faults, displaying a peripheral halo of Au mineralization, and was probability controlled by ore-forming hydrothermal activities. Group 4 (Cd and Mo) exhibited extreme enrichment along the periphery of the F₇ fault. This pattern indicates the presence of a substantial hydrothermal alteration zone surrounding the fault, likely influenced by ore-forming hydrothermal processes. Additionally, Pb, Ag, Cd, Mo, and W are considered essential indicators for ore formation besides Au, As, Sb, Hg, and Tl. Twelve effective association rules were derived using the association rule algorithm, which can aid in discriminating Au mineralization. The spatial distributions of the 15 elements indicated that the F₁₄ fault is the main ore-bearing fracture zone, while the F₇ fault serves as the ore-conducting structure, channeling ore-forming fluids into the F₁₄ fault. Faults between the Wujiaping and Xuman formations, along with their associated reverse faults, present potential prospecting targets both within and outside the Lintan Au deposit in the Youjiang Basin. Exploration geochemical data can be fully utilized by combining factor analysis and association rule algorithms, offering key guidance for prospecting Carlin-type gold and similar deposits. Full article

The Zhen’an-Xunyang Basin is a late Paleozoic rifted basin with a series of Au-Hg-Sb deposits that have been found, mostly along the Nanyangshan fault. Recently discovered large- and medium-sized gold deposits such as the Xiaohe and Wangzhuang deposits exhibit typical characteristics of Carlin-type gold deposits. Therefore, it is imperative to select a typical deposit for an in-depth study of its metallogenic mechanism to support future prospecting efforts targeting the Carlin-type gold deposits within the area. Based on detailed field investigation and microphotographic observation, four ore-forming stages are identified: I, low-sulfide quartz stage, characterized by euhedral, subhedral pyrite, and fine veins of quartz injected parallel to the strata; II, arsenopyrite–arsenian pyrite–quartz stage, the main mineralization stage characterized by strongly silicified zones of reticulated quartz, disseminated arsenopyrite, fine-grained pyrite; III, low-sulfide quartz stage, characterized by large quartz veins cutting through the ore body or fine veins of quartz; Ⅳ, carbonate–quartz stage, characterized by the appearance of a large number of calcite veins. In situ analysis of trace elements and S isotopes of typical metal sulfides was carried out. The results show significant variations in the trace element compositions of metal sulfides in different stages, among which the main mineralization stage differs notably from those of the Au- and As-low surrounding strata. In situ S isotope analysis reveals δ³⁴S values ranging from 15.78‰ to 28.71‰ for stage I metal sulfides, 5.52‰ to 11.22‰ for stage II, and 0.3‰ to 5.25‰ for stage III, respectively, revealing a gradual decrease in S isotopic values from the pre-mineralization stage to post-mineralization stage, similar to those observed in the Xiaohe gold deposit. These features indicate a distinct injection of relatively low ³⁴S hydrothermal fluids during the mineralization process. The element anomalies of the 1:50,000 stream sediment in the region revealed ore-forming element zonation changing in W→Au (W)→Hg, Sb (Au) anomalies from west to east, manifested by the discovery of tungsten, gold, and mercury–antimony deposits in the area. Moreover, conspicuous Cr-Ni-Ti-Co-Mo anomalies were observed on the western side of the Wangzhuang and Xiaohe gold deposits, indicating a potential concealed pluton related to these deposits. These lines of evidence point to a magmatic–hydrothermal origin for the Carlin-type gold deposits in this area. Furthermore, hydrothermal tungsten deposits, Carlin-type gold deposits, and low-temperature hydrothermal mercury–antimony deposits in this region are probably controlled by the same magma–hydrothermal system. Full article

The Nanpanjiang basin hosts the world’s second-largest concentration of Carlin-type gold deposits. To decipher the origin and evolution of hydrothermal fluid, this study conducted Sm–Nd dating, in-situ trace element, and C-O-Sr isotopic analyses on three types of calcite samples from the giant Lannigou gold deposit in the Nanpanjiang basin, SW China. The type-I calcite, intergrown with Au-bearing arsenian pyrite, has an Sm–Nd isochron age of 213 ± 7 Ma (MSWD = 0.81), indicating that gold mineralization occurred in Late Triassic. The type-II calcite, which coexists with high-maturity bitumens and cut through the main-stage gold orebodies, yields an Sm–Nd age of 188 ± 14 Ma (MSWD = 0.34), representing a post-ore hydrocarbon accumulation event. The type-I and type-II calcite samples have low REE contents (5.28–51.6 ppm) and exhibit MREE-enriched and LREE-/HREE-depleted patterns. Combined with their identical C-O-Sr isotopes, we suggest that hydrothermal fluids responsible for the precipitation of type-I and type-II calcite samples were derived from a mixed metamorphic fluid and meteoric water source. In contrast, the type-III calcite samples, associated with realgar and orpiment, have distinct Mn, Sr, and As contents, REE patterns, and C-O-Sr isotopic composition from the type-I and II calcites, suggestive of different fluid sources. Based on our and previously published data, we propose that the fluid evolution, gold mineralization, and hydrocarbon accumulation in the Nanpanjiang basin are closely related to the Indosinian and Yanshanian orogenies in South China. Full article

Arsenious and sulphur-bearing micro-disseminated gold ore is a kind of typical refractory Carlin-Type. The gold in Carlin-Type gold ore grains is distributed finely, existing as invisible or submicroscopic gold, encapsulated in arsenopyrite and pyrite. The technical difficulty of treatment Carlin-Type gold ore lies in how to release the fine gold wrapped in pyrite and arsenopyrite. In this study, the oxidation roasting pre-treatment technique was used to treat the Carlin-Type gold ore. This included a two-stage roasting process: the arsenic was removed in the first roasting process, and the sulphur was removed in the second roasting process. The thermodynamic of the roasting process was analyzed, and the mineral phase evolution of the roasting process was investigated by using XRD, SEM and EDS. Finally, the influence of sodium cyanide dosage and leaching time on leaching efficiency was investigated. The results suggest that for the first roasting temperature at 550 °C, and the second roasting at temperature 700 °C with air flow 2.5 L/min, the sodium cyanide dosage is 1.75 kg/t and leaching time is 27 h; a good leaching efficiency is obtained with 83.85%. Full article