Search Results (15)

The Nuri deposit is currently the only Cu-W-Mo deposit in the Gangdese metallogenic belt, Tibet, China, that contains large-scale tonnages for both Cu and WO₃ resources, accompanied by a medium-scale Mo resources. Previous studies have suggested the potential presence of concealed porphyry-type orebodies at depth, yet effective exploration tools for verifying this hypothesis remain lacking. In this study, microscopic identification, electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were integrated to investigate the mineral chemical characteristics of chlorite from the Nuri deposit. The aim was to evaluate the effectiveness of chlorite geochemistry as an exploration vector for predicting deep concealed porphyry orebodies and to establish corresponding exploration indicators. Chlorite in the deposit can be genetically classified into metasomatic (Chl-I) and hydrothermal (Chl-II) types. Both types are Mg-rich varieties, indicating formation under conditions of low oxygen fugacity and low pH. With decreasing vertical distance to the orebody and toward the southeast direction of the exploration section, the contents of Ti (10–950 ppm) and V (50–820 ppm), as well as the Ti/Sr, Ti/Mn, Ti/Li, and V/Li ratios, progressively increase. In contrast, the concentrations of Li (36–390 ppm), Mn (1270–6730 ppm), Sr (1–510 ppm), and Zn (110–1100 ppm) systematically decrease. These systematic compositional variations demonstrate that chlorite geochemistry is an effective exploration tool in the Nuri mining area and suggest the presence of a concealed mineralization center or porphyry orebody beneath the interval from ZK4501 to ZK4502. Full article

The Liwu copper deposit, located on the western margin of the Yangtze Block, is a typical metamorphic-hosted polymetallic Cu deposit with significant deep exploration potential. To constrain its mineralization-forming processes and primary halo characteristics, this study focuses on the Heiniudong ore segment. Based on portable X-ray fluorescence (XRF) data obtained from drill cores and underground samples, a comprehensive geochemical analysis of 20 elements was conducted. Elemental background values and anomaly thresholds were determined using the iterative sigma (σ) elimination method. Pearson correlation analysis and hierarchical cluster analysis were applied to identify element associations, while the Grigorian zonation index method was employed to investigate axial zoning patterns of primary halos. The results demonstrate that Cu exhibits strong positive correlations with S, Fe, Ag, Cd, Sn, and Bi, indicating a medium- to high-temperature hydrothermal sulfide mineralization system. The primary halo displays well-defined vertical zonation, with Ba–Sr–Sb–As representing the front halo, Zn–Pb–Cu–Ag–Sn–Fe–Cd the near-ore halo, and Bi–Mo–W–Th the tail halo. A clear axial zonation sequence is established. The vertical variation in the geochemical ratio (As × Sr × Sb)/(Mo × Bi × W) exhibits a characteristic “low–high–low–high” pattern, reflecting the superposition of the front halo of a deeper concealed orebody with the tail halo of the upper known orebody under multistage hydrothermal remobilization and structural overprinting. Integrated with the coexistence of front halo and tail halo anomalies and strong alteration in drill hole WT03, the results indicate that the southwestern extension of WT03 along southwest-dipping ductile–brittle detachment structures represents the most promising deep exploration target. Full article

The demand for lead–zinc–antimony ore resources in China has increased steadily, while shallow deposits are approaching depletion, leading to intensified exploration for deep, concealed orebodies. Electro-geochemical surveys, as a penetrative geochemical exploration technique, are particularly effective in areas with thick overburden. In this study, the Bancai area in Hechi, Guangxi, was selected to evaluate the applicability of this method for concealed mineral exploration. Feasibility testing was conducted along the A4 profile over an engineering-controlled orebody. Distinct electro-geochemical anomalies were identified directly above the known orebody, showing strong spatial correspondence and favorable ore-indicating characteristics, confirming the effectiveness of the method in the study area. Based on the deposit’s geological characteristics, prospecting indicators were established by integrating geological features, electro-geochemical responses, and wall-rock alteration. A geological electro-geochemical prospecting model was constructed for the Bancai mining area and applied for deep exploration of the Bancai B block. By analyzing the spatial distribution of electro-geochemical anomalies and integrating geological conditions, mineralization potential, and related factors, three prospective target areas were delineated to provide guidance for subsequent explorations. Among these targets, Target Area III exhibits favorable structural conditions, well-developed calcite veins, and pronounced superposition of multi-element geochemical anomalies, indicating considerable potential for further mineral exploration. Full article

With the deepening of deep mineral exploration, traditional methods face bottlenecks in identifying concealed orebodies, making the establishment of a mineralogical exploration indicator system for collision-type porphyry deposits imperative. This study investigates chlorite from the Cimabanshuo Porphyry Copper Deposit in the Zhunuo Ore Concentration Area of the Western Gangdese via systematic petrographic and in situ geochemical analyses, to elucidate the spatial evolution of its trace element compositions and assess the validity and applicability of different trace elements for hydrothermal center indication. Based on micropetrographic observations, chlorite is classified into three types: biotite-altered (Chl-1), amphibole-altered (Chl-2) and vein-type (Chl-3), with Chl-1 and Chl-2 significantly affected by primary mineral compositions. Trace element results show that spatial variations in Ti, Li, Ni, Co, Mn, and Sr contents and Li/Mn and Ti/Sr ratios in chlorite can clearly indicate the mineralization center—Ti, Li, Ni and Co are systematically enriched in the proximal ore zone by temperature and fluid compositional effects, while Mn and Sr are enriched in the distal ore zone due to elemental redistribution during fluid migration. Fitting analysis of chlorite elemental ratios against the distance from sampling points to the mineralization center indicates the Li/Mn ratio decreases with increasing distance (R² = 0.4665), consistent with elemental distribution and showing a certain correlation; in contrast, the Ti/Sr ratio has a fitting coefficient of determination of only 0.0581, which cannot serve as an effective analysis indicator for this study because the deposit’s plate collision metallogenic setting causes elemental migration to be disturbed by local geological factors. In addition, chlorite in the zones 0–500 m from the Cu I, Cu II, and Cu III orebodies and 1–1.5 km to the north is characterized by significant enrichment of Ti, Li, Ni, and Co, depletion of Mn and Sr and high Li/Mn ratios. Accordingly, a concealed hydrothermal center is inferred in the northern part of the Cimabanshuo Deposit beyond the proven orebodies. Comprehensive studies confirm that the spatial variation characteristics of trace elements in chlorite from the Cimabanshuo Porphyry Copper Deposit have high applicability for indicating hydrothermal mineralization centers. Full article

The oblique distribution of orebodies is a fundamental characteristic of the spatial arrangement of orebody groups in non-magmatic hydrothermal deposits and is closely related to shearing. The Daliangzi Pb–Zn deposit in the Sichuan–Yunnan–Guizhou Pb–Zn polymetallic metallogenic area is a typical representative of epigenetic hydrothermal deposits controlled by a strike-slip–fault-fold structure. However, the underlying ore-controlling mechanism of this strike-slip–fault-fold structure remains unclear; as a result, achieving breakthroughs in mineral exploration in the deposit’s deep and peripheral zones is directly hindered. This paper focuses on the Daliangzi Pb–Zn deposit. Based on the Theory and Methods of Ore-field Geomechanics, the hierarchical structural ore-controlling pattern of the deposit is clarified, identifying the NE-trending tectonic zone from the Middle-Late Indosinian to Early Yanshanian as the Pb–Zn metallogenic tectonic system. It proposes the spatial oblique distribution patterns of the deposits, ore sections, orebodies, and ore blocks, along with the mechanical mechanisms of multi-scale structural ore control. A compound negative flower structure–fault-fold–diapiric ore-controlling model was constructed for the Daliangzi Pb–Zn deposit. Finally, the locations of concealed orebodies at different scales within the Daliangzi Pb–Zn deposit and its surrounding areas were predicted; moreover, the locations of concealed orebodies at various depths within the deposit area were also predicted. Full article

The Laoliwan Ag-Pb-Zn deposit is situated in the southern margin of the North China Craton and represents the first large-scale Ag-Pb-Zn ore deposit discovered in the Xiaoshan District. Ag-Pb-Zn orebodies are structurally controlled by NW- and NNW-trending faults and primarily hosted within early Cretaceous granite porphyry intrusions. In this study, sulfide Rb-Sr isotope dating and C-H-O-S-Pb multiple isotope compositions were conducted to constrain the ore genesis of this deposit. The Rb-Sr isotopic data of sulfides yield a weighted mean isochron age of 132.8 ± 9.5 Ma and an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7115 ± 0.00016, indicating that mineralization occurred during the early Cretaceous and the ore-forming materials were derived from a crust–mantle mixed reservoir. The δ¹³ C (−1.3‰ to 0.7‰), δD (−96.3‰ to −86.7‰) and δ¹⁸O_H2O (0.3‰ to 5.6‰) values suggest that the ore-forming fluids were mainly derived from magmatic water with a contribution of meteoric water during mineralization. The δ³⁴S values of sulfides (+2.0‰ to +5.8‰) indicate a magmatic source. The Pb isotope data (²⁰⁶Pb/²⁰⁴Pb = 17.301–17.892, ²⁰⁷Pb/²⁰⁴Pb = 15.498–15.560, ²⁰⁸Pb/²⁰⁴Pb = 37.873–38.029) also reveal that the ore-forming materials originated from the lower crust with a small amount from the mantle source. By integrating geochronological and geochemical data, this study proposes that the Laoliwan Ag-Pb-Zn deposit is characterized as an epithermal deposit, with potential for the discovery of concealed porphyry Cu-Mo mineralization at depth. It is inferred to be related to tectonic–magmatic–fluid activities in the context of early Cretaceous lithospheric thinning along the southern margin of the North China Craton. Full article

The Xintianling deposit, a skarn-type tungsten mineralization system in the Nanling Range of South China, presents significant challenges in identifying new high-grade orebodies. This study employs an integrated approach, combining the opposing-coil transient electromagnetic (OCTEM) method with geochemical exploration, to delineate and evaluate concealed mineralization within and beyond the known mining area. High-precision geophysical surveys revealed low-resistivity anomalies along the contact zone between Jurassic granite and the Carboniferous Shidengzi Formation limestone. Integration of these anomalies with geochemical element associations (W-Sn-Fe-Bi and Cu-Mo-As) highlights signatures indicative of tungsten mineralization. The results demonstrate that skarn-type orebodies in the mining area are primarily controlled by the axial planes of N–S-striking anticlines and associated secondary folds, with thick, large orebodies preferentially forming in depressions along the granite roof. Comprehensive analysis of the geophysical and geochemical data identified 15 low-resistivity anomalies in the Shanglongshan–Huanggualing target area, of which 14 are interpreted as potential skarn-type mineralized bodies, thereby delineating three potential exploration targets. This integrated methodology establishes a robust scientific foundation for deep and peripheral prospecting in the mining area and provides methodological guidance for exploring similar skarn-type tungsten deposits. Full article

The Early Cretaceous Halasheng deposit, located in the southern Erguna Block, is an intermediate sulfidation epithermal Ag-Pb-Zn deposit in the Derbugan metallogenic belt. The Halasheng deposit comprises both proximal skarn mineralization and distal hydrothermal vein-type Pb-Zn-Ag mineralization, which can be further divided into three stages represented by Fe-As-S, Pb-Zn-Cu-Fe-S, and Ag-Pb-Zn-Sb-S element associations. The main ore minerals in the Halasheng deposit include galena, sphalerite, pyrite, arsenopyrite, chalcopyrite, bournonite, falkmanite, and argentiferous minerals. Visible silver in the form of independent argentiferous minerals, mainly including freibergite, polybasite, stromeyerite, pyrargyrite, acanthite, and native silver, is the major type of silver occurring in the Halasheng district. Fluid inclusion studies of sphalerite and quartz from different mineralization stages revealed that skarn mineralization has the relatively highest homogenization temperature (322~398 °C), while in the vein-type hydrothermal mineralization stage, the homogenization temperature has a declining trend from the early stage to late stage (from 300~350 °C to 145~236 °C). In the whole mineralization process, the salinity of ore-forming fluids is almost constant at a relatively high level (10.5~21.9 wt% NaCl). Fluid cooling, or fluid–wallrock reaction, is supposed to be the major cause of metal precipitation in the Halasheng deposit. Through an analogy with the typical Ag-Pb-Zn deposits in the Derbugan metallogenic belt, it is suggested that the discovered orebodies in the Halasheng deposit likely belong to the shallow part of the epithermal system, and there is high potential to discover Zn, Cu-Zn orebodies, and even porphyry Mo-Cu mineralization. In terms of regional ore prospecting, Early Cretaceous intermediate-acid intrusions have the potential to form related Ag-Pb-Zn deposits and should receive special attention. Furthermore, places where Lower Cambrian marbles are exposed or concealed are favorable settings for skarn mineralization. Full article

The supergiant Shuangjianzishan (SJS) Ag–Pb–Zn deposit, located in the southern Great Xing’an Range (SGXR), is the largest Ag deposit in China. The SJS deposit can be divided into two ore blocks: the Shuangjianzishan ore block and the Xinglongshan ore block. Given the importance of the Xinglongshan ore block in the SJS deposit, our work is focused on the Xinglongshan ore block. The vein orebodies in the Xionglongshan ore block mainly occur in the NW-, NNW-, and NNE-trending fault zones, and its mineralization is mainly related to a deep concealed syenogranite. Here, we present new geochronology, isotope geochemistry, and fluid inclusion data for the Xinglongshan ore block and provide additional insights into the metallogenic mechanism of the deposit. The dating results show that the syenogranite related to the mineralization formed at approximately 137 Ma, which is coherent with some previous age determinations in sulfides from the ore deposit. The mineralization of the Xinglongshan ore block can be divided into four stages: sphalerite–arsenopyrite–pyrite–chalcopyrite–quartz stage (stage I), sphalerite–galena–pyrite–silver-bearing mineral–quartz stage (stage II), sphalerite–galena–silver-bearing mineral–quartz–calcite stage (stage III), and weakly mineralized quartz–calcite stage (stage IV). Four types of fluid inclusions (FIs) have been identified within quartz and calcite veins: liquid-rich, gas-rich, pure-liquid, and pure-gas FIs. The homogenization temperatures in the four stages exhibit a gradual decrease, with stage I ranging from 253 to 302 °C, stage II from 203 to 268 °C, stage III from 184 to 222 °C, and stage IV from 153 to 198 °C, respectively. The salinity for stages I, II, III, and IV falls within the ranges of 3.4–6.6 wt% NaCl eqv., 2.6–7.2 wt% NaCl eqv., 2.9–7.0 wt% NaCl eqv., and 1.2–4.8 wt% NaCl eqv., respectively, indicative of a low-salinity ore-forming fluid. The δ¹⁸O_water and δD values of the ore-forming fluid span from −13.9‰ to 7.4‰ and −145‰ to −65‰, with δ¹³C_V-PDB values between −11.0‰ and −7.9‰. These values suggest that the ore-forming fluid predominantly originated from a mixture of magmatic and meteoric water. The ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios of sulfides range from 18.278 to 18.361, 15.530 to 15.634, and 38.107 to 38.448, respectively. These ratios imply that the ore-forming material was primarily derived from the Early Cretaceous granitic magma, which resulted from the mixing of depleted mantle- and crustal-derived magmas. The fluid mixing was the dominant mechanism for mineral precipitation. The Xinglongshan ore block belongs to a magmatic-hydrothermal vein-type deposit related to the Early Cretaceous syenogranite, and the Shuangjianzishan ore block belongs to an intermediate sulfidation epithermal deposit related to coeval subvolcanic rocks. The Ag–Pb–Zn mineralization at Shuangjianzishan is genetically related to the Early Cretaceous volcanic–intrusive complex. Full article

The Sarakan Gold Deposit is located in the vicinity of the Songsanu and Napafa villages, north of Sarakan County, Vientiane Province, Laos. It forms part of the Luang Prabang–Loei polymetallic metallogenic belt, and its metallogenic geological conditions are good and mineral resources are abundant. At present, most orebodies (mineralization) are deeply buried and greatly vary in terms of their characteristics; furthermore, the distribution and output of orebodies (mineralization) are not clear, which makes it difficult to find minerals in the area. Based on the comprehensive geological characteristics, geophysical anomalies, and interpretation results in the study area, it is believed that the Sarakan Gold Deposit is closely related to Indosinian felsic substance magmatic intrusions and is controlled by their structure. The type of deposits in the belt are brittle–ductile, shear structured, Quartz-pyrite, vein-type gold deposits. In this study, we carried out comprehensive geophysical methods, including the high-precision magnetic survey, induced polarization survey, and the transient electromagnetic measurement. Based on the characteristics of geophysical anomalies, geological inference, and interpretation, the integrated geophysical and geochemical prospecting criteria of the ore area have been determined: high magnetism, high polarization, and medium–high resistance are the signs pointing to concealed mineralization bodies in the study area, and this provided the best framework for us to discuss the deep geological bodies in the study area. The drilling verification results are consistent with the abnormalities delineated by the magnetic and electrical measurements. Our geophysical exploration results revealed the coupling relationship between the concealed intrusive body of the Sarakan Gold Deposit and the metallogenic structure, which provided a great opportunity for finding potentially similar deposits in the Luang Prabang–Loei polymetallic metallogenic belt. Full article

With a focus on the Cu isotope geochemistry of chalcopyrite, this paper analyzed the Cu isotope geochemistry of the Qibaoshan crypto-explosive breccia-type Cu–Au polymetallic ore district in Wulian, Shandong Province, North China Craton (NCC). Combined with the results of the in situ sulfur isotope analysis of sulfides, a certain reference and evidence for the study of the genetic mechanism of the epithermal-porphyry Cu polymetallic metallogenic system were provided. The results of the in situ isotope analysis show that the δ³⁴S values of the main sulfides in the Qibaoshan Cu–Au polymetallic ore district range from −6.81‰ to +3.82‰ and are likely to be attributed to the mixing of the derived mantle with the surrounding sedimentary rock assimilation. The ore-forming mechanism may be related to the progressive cooling and transition of the earliest hydrothermal fluids that were dominated by H₂S under relatively reducing conditions, followed by a gradual transition from oxidation to reduction. The Cu isotopic composition of the sulfides in ores (δ⁶⁵Cu = +0.169‰–+0.357‰) decreases with depth, which is likely caused by the upward transport of heavier Cu isotopes. The upper part of the crypto-explosive breccia pipe in the Qibaoshan area may be relatively more gaseous, resulting in the enrichment of δ⁶⁵Cu. As the gas phase decreases and the liquid phase increases with depth, the δ⁶⁵Cu value gradually decreases. This indicates the transition from a low-temperature phyllic alteration to a high-temperature K-feldspar alteration. Large, concealed pluton intrusions or orebodies may be present at a depth of the Qibaoshan area. The heavy δ⁶⁵Cu characteristic is a potential indicator for tracing the fluid activity of the porphyry system and searching for Cu mines. The results provide a reference for the study of the genetic mechanisms of the epithermal-porphyry Cu polymetallic metallogenic system. Full article

In recent years, the exploration of concealed deposits has become extremely urgent as the shortage of surface resources worsens. In this study, naturally formed nanoparticles in five media (deep-seated fault gouge, ascending gas flow, soil, shallow groundwater and deep groundwater) in Chaihulanzi Au deposit, China, were analyzed by transmission electron microscopy. The characteristics of category, shape, lattice parameters, chemical component and association were obtained. The results show that deep media can carry natural nanoparticles to the surface media, resulting in an increased proportion of O and metal chemical valence such as Pb and Cu in nanoparticles. The metal elements Au, Ag, Cu, Zn and As in nanoparticles correspond to those of orebody minerals. Au-Ag-Cu, Fe-As, Cu-Sn and Pb-Zn element associations in nanoparticles are similar to those of mineral composition or orebody paragenesis in Chaihulanzi deposit. Compared with nanoparticle characteristics in deposit and background areas, it can be deduced that natural ore-bearing nanoparticles come from concealed orebodies. With the characteristics of more oxide forms and the dislocation of the crystal lattice, these nanoparticles are formed by faulting and oxidation. Nanoparticles produced in concealed orebodies that migrate from the deep to the surface media could be used for prospecting. Full article

Typical stratiform-like cassiterite–sulfide orebodies formed at 160–150 Ma cut by a steep hydrothermal vein-type orebody were discovered in the Xianghualing tin–polymetallic orefield, which implied a new phase of magmatism and mineralization later than the Late Jurassic stage. Hence, a systematic study of the characteristics and genesis of the concealed Laohuya granite, including U–Pb age, trace elements, Lu–Hf isotopes of zircons, and whole-rock major- and trace-elements, is examined in this paper. The zircon U–Pb dating yielded a Concordia age of 87.75 ± 1 Ma, confirming the existence of Late Cretaceous magmatism in the Xianghualing tin–polymetallic orefield. The Laohuya granite is classified as syenogranite and belongs to the peraluminous, high K calc-alkaline series. It is a highly evolved A₂-type granite with ε_Hf(t) values ranging from −14.97 to −7.59 and two-stage model ages (T_DM2) ranging from 2939 to 2280 Ma. Combining chronology, petrochemistry, isotopic geochemistry, and previous tectonic studies, we believe that the Laohuya granite originated from the partial melting of a reworked ancient crust composed of TTGs, and its weathered sediments formed in subduction or collision zones at 2.5 Ga, controlled by the reactivation of the Chenzhou–Linwu deep fault in the extensional setting of South China during the Late Cretaceous. Full article

The large Shuangwang gold deposit (>80 t gold) is located in the Western Qinling Orogen (WQO) of central China. It is an orogenic-type gold deposit hosted in an NW-extending breccia belt in the Devonian Xinghongpu Formation. Gold mineralization of the Shuangwang deposit is featured by hydrothermal breccia ores with strata fragments cemented by hydrothermal minerals dominated by ankerite, quartz, and pyrite with minor amounts of calcite and albite. Pyrite is the major gold-hosting sulfide and the most abundant ore mineral. Crystal habits, thermoelectricity, and trace-element composition of pyrites from the main ore-forming stage of the Shuangwang gold deposit were studied by microbinocular, BHTE-06 thermoelectric coefficient measuring instrument, and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Spatial distribution of the above data for pyrites was delineated by contour maps of morphology index, P-type frequency, and primary halo elements (e.g., supraore halo elements Ba and Sb; near-ore halo elements Pb, Zn, and Cu; and subore halo elements Co, Mo, and Bi). Based on the above results, four target areas (areas between prospecting lines 0 and 1, between lines 14 and 18 below orebody KT9; areas between prospecting lines 30 and 34, between lines 44 and 46 below orebody KT8) were put forward for deep gold exploration in the future. These targets are consistent with the depth extrapolation of proven gold orebodies, indicating the practicality of typomorphic characterization of pyrites as vector to deep/concealed gold orebodies. The effectiveness of the pyrite typomorphic parameter for deep gold prediction seems to be chemical composition, crystal habits, and then thermoelectricity. Full article

The newly discovered Tiegelongnan Cu (Au) deposit is a giant porphyry deposit overprinted by a high-sulfidation epithermal deposit in the western part of the Bangong–Nujiang metallogenic belt, Duolong district, central Tibet. It is mainly controlled by the tectonic movement of the Bangong–Nujiang Oceanic Plate (post-subduction extension). After the closure of the Bangong–Nujiang Ocean, porphyry intrusions emplaced at around 121 Ma in the Tiegelongnan area, which might be the result of continental crust thickening and the collision of Qiangtang and Lhasa terranes, based on the crustal radiogenic isotopic signature. Epithermal overprinting on porphyry alteration and mineralization is characterized by veins and fracture filling, and replacement textures between two episodes of alteration and sulfide minerals. Alunite and kaolinite replaced sericite, accompanied with covellite, digenite, enargite, and tennantite replacing chalcopyrite and bornite. This may result from extension after the Qiangtang–Lhasa collision from 116 to 112 Ma, according to the reopened quartz veins filled with later epithermal alteration minerals and sulfides. The Tiegelongnan deposit was preserved by the volcanism at ~110 Ma with volcanic rocks covering on the top before the orebody being fully weathered and eroded. The Tiegelongnan deposit was then probably partly dislocated to further west and deeper level by later structures. The widespread post-mineral volcanic rocks may conceal and preserve some unexposed deposits in this area. Thus, there is a great potential to explore porphyry and epithermal deposit in the Duolong district, and also in the entire Bangong–Nujiang metallogenic belt. Full article