Hydrothermal Deposits Research Articles

Evaluation of normalization methods applied to Short-Wavelength Infrared (SWIR) spectroscopy mineral databases from multiple instruments and for vectoring analysis exploration

Over the past decade, short-wave infrared (SWIR) spectroscopy has made significant advances in detecting geochemical variations in minerals like white mica, alunite, and chlorite for exploring hydrothermal ore deposits. These variations provide valuable clues, indicating changes in temperature, pH, and fluid oxidation state towards the mineralized center. However, small calibration differences among devices challenge data integration. This study evaluates the 2200 nm Al-OH absorption feature in four white mica SWIR spectroscopy databases collected by TerraSpec™ and OreXpress™ from samples at the Grasshopper porphyry prospect. It evaluates three normalization methodologies: rescaling, mean normalization, and Z-score, yielding p-values for successful data merging of up to 0.75. Findings suggest effective normalization methods across devices, reducing biases from uncalibrated spectrometers. This research offers a methodology to correct SWIR database biases, facilitating accurate data integration across instruments for vectoring analysis.

Fluid evolution and genesis of the Yidinan granitoid-hosted orogenic gold deposit (China)

Abstract The metamorphic model explaining orogenic gold ore formation has become widely accepted. However, there has been extensive debate regarding whether a magmatic-hydrothermal system contributes fluids or metals in the source of orogenic gold deposits. The Yidinan gold deposit is hosted by Triassic quartz diorite in the West Qinling Orogen, China, which is controlled by NNE-trending high-angle brittle-ductile faults. The gold mineralization is characterized by vein and disseminated type ores comprising auriferous pyrite and arsenopyrite. Magmatic apatite U-Pb and magmatic biotite Ar-Ar dating pinpoint the emplacement and the cooling of ore-hosting quartz diorite at 241.8 ± 2.8 Ma and 241.7 ± 0.32 Ma, respectively. In situ U-Pb dating of hydrothermal monazite yield an age of 234.6 ± 2.8 Ma for the gold mineralization. Systematic fluid inclusion investigation suggests that the ore-forming fluids belong to a NaCl-H2O-CO2 ± CH4 system with low salinity (5.76–10.09 wt% NaCl equiv.) and medium temperatures (253–395 °C). During fluid evolution, phase separation occurred, with CO2 and other gases preferentially fractionating into the vapor phase. The sulfur isotope data range from 5.50‰ to 7.85‰ and are higher than those from the nearby magmatic-hydrothermal deposits. Such results support that the gold-bearing fluids were sourced from devolatilization of underlying sedimentary rocks during regional metamorphism. Fluid immiscibility caused by fault-valve processes might be the critical mechanism for the gold deposition. Although the geological and geochronological evidence suggested gold mineralization was spatially and temporally associated with the quartz diorite, the ore-forming fluids are not consistent with a magmatic source; therefore, the Yidinan gold deposit is of an orogenic type. This study reveals that despite orogenic gold mineralization and magmatic activities showing a broad temporal or spatial overlap during orogenesis processes, there is no genetic link between gold mineralization and granitic magmatism in many hydrothermal gold deposits. The low-salinity auriferous metamorphic fluid was released from underlying metasedimentary sequences during orogenesis. The rapid cooling of the granitoid after emplacement further prevented it from contributing to gold-bearing fluid formation or creating the necessary pressure-temperature conditions for gold deposition.

Role of As in the formation of giant Au deposits: Insights from sulfur isotope and geochemistry of pyrite from the Shuangwang Au deposit, West Qinling, central China

Role of As in the formation of giant Au deposits: Insights from sulfur isotope and geochemistry of pyrite from the Shuangwang Au deposit, West Qinling, central China

Bifunctional Cofe-Spinel@Cu for Peroxymonosulfate Activation and Electrochemical Nitrate Reduction Towards High Purity Ammonia Production

Ammonia is a valuable chemical feedstock and energy carrier with lower corbon footprint during conversion to H2. Haber-Bosch process is the predominant method for industrial NH3 production, but it is associated with high energy consumption and substantial CO2 emission. Recently, electrochemical nitrate reduction reaction (NO3RR), powered by renewable energy in ambient condition, has emerged as a promising method for sustainable NH3 production from nitrate containing wastewater. However, the purity of generated NH3 by NO3RR is also a critical issue that has been overlooked in state-of-the-art reports. In the case of nuclear and steelmaking wastewater, abundant nitrate ions and organic pollutants coexist. Therefore, additional step is required to separate the NH3 generated by the NO3RR from the wastewater matrix. Herein, we designed a coupled NO3RR-PMS activation electrocatalytic system to achieve a high-purity NH3 production. CoFe-spinel on Cu foam (CoFe/CF) was employed both as a cathode for NO3RR and catalyst for chemical PMS activation. The CoFe-spinel was prepared through a straightforward hydrothermal deposition on Cu foam, followed by cathodization in nitrate solution. It achieved 90% faradaic efficiency for NO3 --to-NH3 conversion and NH3 production rate of 1.10 mmol h-1 cm-2 at -0.4 V RHE, together with long-term durability for about 150 h (in 0.1 M nitrate solution at pH 14). Additionally, it demonstrated approximately 90% efficiency in removing organic pollutants via PMS activation (with 10 mg L-1 SMX solution at pH 14). Thus, the coupled NO3RR-PMS activation system, utilizing the CoFe/CF catalyst, produced NH3 with a high purity. The cathodization step generated CoFe2O4 nanostructure with well-developed oxygen vacancies, to provide plentiful active hydrogen for the observed cutting-edge figures of merit for NO3 --to-NH3 conversion. Operando analysis based on X-ray absorption spectroscopy is ongoing to reveal the genuine active site for PMS activation or NO3RR. The proposed system would offer an efficient technology for high-purity NH3 production from nitrate wastewater.

Nanoparticle attachment promotes nugget effect of Au-rich metallic melts in hydrothermal ore deposits

The role of bismuth melts in scavenging Au from hydrothermal fluids has been increasingly recognized in the last decade, but the question of how the Au extracted by such melts transforms into nuggets to form high-grade ores remains obscure. Here, we have characterized the nanostructure of gold nanoparticles (AuNPs) in Bi-rich gold ores that precipitated from Bi-Au melts and propose a novel model to explain the genesis of gold nuggets. This model comprises three consecutive processes of Au crystallization in these melts into coarse grains: the initial formation of atomic clusters equivalent to Au nucleation, the coalescence of these clusters into low-crystalline AuNPs followed by their transformation into well-structured ones, and finally the preferential attachment of these NPs along the {111} lattice plane. This atomic crystallization pathway bridges the gap between Au scavenging by metallic melts and nugget formation, thus making the picture of the formation of high-grade gold ores in the context of melt-fluid interaction more complete.

Differences in Sm/Nd ratios between early magmatic and late sulfides: The role of fluids and Nd mobility

Differences in Sm/Nd ratios between early magmatic and late sulfides: The role of fluids and Nd mobility

Silician zoning of magnetite in a Fe skarn deposit: A potential low-temperature indicator in magmatic-hydrothermal systems?

Silician zoning of magnetite in a Fe skarn deposit: A potential low-temperature indicator in magmatic-hydrothermal systems?

Ore sulfur of Golovnin Volcano, Kunashir Island

Research subject. Hydrothermal deposits of Golovnin Caldera. Aim. To study the epithermal volcanogenic ore formation. Key points. Until now, there has been a consensus on the exogenous sedimentary (colloidal) genesis of sulfur in volcanic lakes. Our observations and microstructure studies indicate the presence of sulfur melt at the bottom of Kipyaschee Lake. Drops of this melt are carried to the surface of the lake as part of a light gray foam. The significant differences of sulfur spherules in the concentration of sulfide mineralization, in its composition, as well as in the presence or absence of numerous opal inclusions are most simply explained by the capture of droplets in various parts of the sulfur melt and their subsequent movement by a gas stream passing through the melt. Elemental sulfur condensate is formed in bottom sediments as a result of forced cooling of endogenous gas flows by lake water. The main condensation of sulfur occurs here (96% or more of the total potential of fluid sulfur). Residual condensation of sulfur occurs in the aquatic environment. Finely dispersed sulfur condensate in a mixture with water is unstable and breaks down over time with the release of hydrogen sulfide and the formation of sulfurous and sulfuric acids. The activity of bottom hydrotherms and coastal unrest prevents the formation of colloidal sulfur sediment at the bottom of lakes. In the crater depressions at the bottom of the lakes of the Golovnin Caldera, sulfidization of its melt occurs simultaneously with the condensation of sulfur itself. Gravitational deposition of sulfides in the sulfur melt leads to their enrichment of the root parts of crater depressions, where pyrite ore bodies are formed in real time. Terrestrial sulfur deposits, together with the modified rocks overlying them, demonstrate the full profile of endogenous apical oxidation under gas-hydrothermal action: sulfur and sulfur-opal rocks up the section are replaced by gypsum-jarosite rocks and, further, by an “iron hat” of limonite-cemented breccias of the dome mantle. Conclusions. Observations, microstructure studies and molecular chemical modeling indicate the endogenous condensate origin of ore sulfur in the Golovnin Caldera and exclude its exogenous sedimentary genesis.

Genesis of the Bailugou Vein-Type Zinc-Lead-Silver Deposit, Eastern Qinling Orogen, China: Constraints from Ore Geology and Fluid Inclusions

The Bailugou vein-type zinc-lead-silver deposit is located in the Eastern Qinling Orogen, China. There has been a long-standing debate about whether its formation is related to magmatism or metamorphism. To determine the origin of ore-forming materials and fluids, we conducted a geological and fluid inclusion investigation of the Bailugou. Field surveys show that the vein-type orebodies are controlled by faults in the dolomitic marbles of the Mesoproterozoic Guandaokou Group, and they are distal to the regional Yanshanian intrusions. Four ore stages, i.e., quartz–pyrite ± sphalerite (Stage 1), quartz–polymetallic sulfides (Stage 2), dolomite–polymetallic sulfides (Stage 3), and calcite (Stage 4), are identified through microscopic observation. The homogenization temperatures of measured fluid inclusions vary in the range of 100 °C to 400 °C, with the dominating concentration at 350 °C to 400 °C, displaying a descending trend from early to late stages. The estimated formation depth of the Bailugou deposit varies from 2 km to 12 km, which is deeper than the metallogenic limit of the epithermal hydrothermal deposit but conforms to the typical characteristics of a fault-controlled deposit. The ore-forming fluid in Stage 1 originates from a fluid mixture and experiences a phase separation (or fluid immiscibility) between the metamorphic-sourced fluid and the fluids associated with ore-bearing carbonate-shale-chert association (CSC) strata. This process results in the transition to metamorphic hydrothermal fluid due to water–rock interactions in Stage 2, culminating in gradual weakening and potential fluid boiling during the mineralization of Stage 3. Collectively, the Bailugou lead-zinc-silver mineralization resembles an orogenic-type deposit formed by metamorphic fluids in the Qinling Yanshanian intracontinental orogeny.

Neogene Hydrothermal Fe‐ and Mn‐Oxide Mineralization of Paleozoic Continental Rocks, Amerasia Basin, Arctic Ocean

AbstractRocks dredged from water depths of 1,605, 2,500, 3,300, and 3,400 m in the Arctic Ocean included Paleozoic continental rocks pervasively mineralized during the Neogene by hydrothermal Fe and Mn oxides. Samples were recovered in three dredge hauls from the Chukchi Borderland and one from Mendeleev Ridge north of Alaska and eastern Siberia, respectively. Many of the rocks were so pervasively altered that the protolith could not be identified, while others had volcanic, plutonic, and metamorphic protoliths. The mineralized rocks were cemented and partly to wholly replaced by the hydrothermal oxides. The Amerasia Basin, where the Chukchi Borderland and Mendeleev Ridge occur, supports a series of faults and fractures that serve as major zones of crustal weakness. We propose that the stratabound hydrothermal deposits formed through the flux of hydrothermal fluids along Paleozoic and Mesozoic faults related to block faulting along a rifted margin during minor episodes of Neogene tectonism and were later exposed at the seafloor through slumping or other gravity processes. Tectonically driven hydrothermal circulation most likely facilitated the pervasive mineralization along fault surfaces via frictional heating, hydrofracturing brecciation, and low‐ to moderate temperature Fe‐ and Mn‐rich hydrothermal fluids, which mineralized the crushed, altered, and brecciated rocks.

Heterogeneous Nucleation Regulation Amends Unfavorable Crystallization Orientation and Defect Features of Antimony Selenosulfide Film for High‐Efficient Planar Solar Cells

AbstractAntimony selenosulfide (Sb2(S,Se)3) has obtained widespread concern for photovoltaic applications as a light absorber due to superior photoelectric features. Accordingly, various deposition technologies have been developed in recent years, especially hydrothermal deposition method, which has achieved a great success. However, device performances are limited with severe carrier recombination, relating to the quality of absorber and interfaces. Herein, bulk and interface defects are simultaneously suppressed by regulating heterogeneous nucleation kinetics with barium dibromide (BaBr2) introduction. In details, the Br adsorbs and dopes on the polar planes of cadmium sulfide (CdS) buffer layer, promoting the exposure of nonpolar planes of CdS, which facilitates the favorable growth of [hk1]‐Sb2(S,Se)3 films possessing superior crystallinity and small interface defects. Additionally, the Se/S ratio is increased due to the replacement of Se by Br, causing a downshift of the Fermi levels with a benign band alignment and a shallow‐level defect. Moreover, Ba2+ is located at grain boundaries by coordination with S and Se ions, passivating grain boundary defects. Consequently, the efficiency is increased from 7.70 % to 10.12 %. This work opens an avenue towards regulating the heterogeneous nucleation kinetics of Sb2(S,Se)3 film deposited via hydrothermal deposition approach to optimize its crystalline orientation and defect features.

Heterogeneous Nucleation Regulation Amends Unfavorable Crystallization Orientation and Defect Features of Antimony Selenosulfide Film for High-Efficient Planar Solar Cells.

Antimony selenosulfide (Sb2(S,Se)3) has obtained widespread concern for photovoltaic applications as a light absorber due to superior photoelectric features. Accordingly, various deposition technologies have been developed in recent years, especially hydrothermal deposition method, which has achieved a great success. However, device performances are limited with severe carrier recombination, relating to the quality of absorber and interfaces. Herein, bulk and interface defects are simultaneously suppressed by regulating heterogeneous nucleation kinetics with barium dibromide (BaBr2) introduction. In details, the Br adsorbs and dopes on the polar planes of cadmium sulfide (CdS) buffer layer, promoting the exposure of nonpolar planes of CdS, which facilitates the favorable growth of [hk1]-Sb2(S,Se)3 films possessing superior crystallinity and small interface defects. Additionally, the Se/S ratio is increased due to the replacement of Se by Br, causing a downshift of the Fermi levels with a benign band alignment and a shallow-level defect. Moreover, Ba2+ is located at grain boundaries by coordination with S and Se ions, passivating grain boundary defects. Consequently, the efficiency is increased from 7.70 % to 10.12 %. This work opens an avenue towards regulating the heterogeneous nucleation kinetics of Sb2(S,Se)3 film deposited via hydrothermal deposition approach to optimize its crystalline orientation and defect features.

A Catalyst Tube-Equipped Dual-Stage Tube Furnace System for Accurate Hg Isotopic Determination of Ore Samples Using Neptune Plus Multicollector Inductively Coupled Plasma Mass Spectrometry.

Mercury (Hg) isotopes, which display mass-dependent fractionation and mass-independent fractionation, provide a multidimensional tracer to decipher the source of metals in mineral deposits. However, mineral ore samples usually contain abundant interfering elements (e.g., Te) that can cause inaccurate Hg isotopic analysis. Available acid digestion and combustion methods failed to remove these interfering elements, hindering the application of Hg isotopes for metallogenetic tracing. Here, we developed a new dual-stage tube furnace system employing a Mn-containing catalyst tube to pretreat mineral ore samples. This method yielded good Hg recoveries (100.5 ± 3.8%, 1SD, n = 15) and low levels of interfering elements in sample solutions, allowing for accurate analysis of a series of ore standard reference materials (GBW-11108v: coal; GSO-3: Cu-Ag sulfide ore; GBW 07859: Au-Te sulfide ore). The new method was also successfully applied to measure the Hg isotopic composition of magmatic and hydrothermal ore deposits, which yielded a large range in Δ199Hg value (-0.19 to 0.22‰) for ore deposits formed in different geological settings, highlighting the future applications of this method for metallogenic tracing, especially tracing the source of metals in mineral ore deposits.

A Comprehensive Geophysical Exploration of Sedimentary Exhalative Deposits: An Example from the Huaniushan Lead–Zinc–Silver Polymetallic Deposit in Gansu, China

The Huaniushan lead–zinc–silver deposit is a hydrothermal sedimentary exhalative deposit (SEDEX), and the mining area has complex geological conditions, with the main tectonic structure being the Huaheitan–Shuangfengshan Fault (F3), which controls the distribution of strata and magmatic rocks. Since the discovery of the Huaniushan lead–zinc–silver deposit, diverse interpretations of its genesis and metallogeny have been proposed, making it challenging to establish a definitive geological explanation. Moreover, using a single geophysical exploration method relies on limited rock physical parameters, making it difficult to effectively characterize underground structures. The combined use of multiple geophysical methods can effectively integrate the geophysical characteristics of different rock physical parameters, reducing the multiplicity and uncertainty of the inverse interpretation of geophysical data. The comprehensive interpretation of three-dimensional inversion based on various geophysical data, the construction of geological–geophysical models on geological grounds, the establishment of hidden ore exploration and positioning, and the rapid evaluation of geophysical technological systems are the current research trends in mineral exploration. In light of this, in this study, we conducted research on the three-dimensional inversion interpretation of gravity and magnetoelectric exploration data of the Huaniushan sedimentary exhalative lead–zinc–silver polymetallic deposit and constructed a three-dimensional geological–geophysical model of the study area based on the obtained three-dimensional physical structure of the underground density, magnetization intensity, resistivity, and polarizability of the study area, in combination with related geological and drilling hole data. Finally, we comprehensively interpreted the favorable mineralization sites in the study area.

Development of hydrophilic carbon fiber textiles using seed-assisted hydrothermal deposition of ZnO nanostructures for enhanced interfacial interaction in CFRP composites

Development of hydrophilic carbon fiber textiles using seed-assisted hydrothermal deposition of ZnO nanostructures for enhanced interfacial interaction in CFRP composites

Geochronology, in-situ elements and sulfur isotopes of sulfides from the Songjiashan cobalt-iron deposit in the Zhongtiao mountains of North China Craton: Implications for cobalt occurrence and ore genesis

Geochronology, in-situ elements and sulfur isotopes of sulfides from the Songjiashan cobalt-iron deposit in the Zhongtiao mountains of North China Craton: Implications for cobalt occurrence and ore genesis

Genesis of the Ulaan silver-lead–zinc deposit in Northeast Mongolia: Constraints from S and Pb isotopes, together with U-Pb and Rb-Sr geochronology

Genesis of the Ulaan silver-lead–zinc deposit in Northeast Mongolia: Constraints from S and Pb isotopes, together with U-Pb and Rb-Sr geochronology

Contribution of bismuth melts to gold endowment in the Baolun gold deposit, Hainan Island, South China

Contribution of bismuth melts to gold endowment in the Baolun gold deposit, Hainan Island, South China

ZnO/AgSbO3 as an improved nanophotocatalyst in the synthesis of some naphthopyranopyrimidines

ZnO/AgSbO3 as an improved nanophotocatalyst in the synthesis of some naphthopyranopyrimidines

Quantifying element mass transfer in the Jiling Na-metasomatic hydrothermal uranium deposit, Northwest China

The Na-metasomatic hydrothermal uranium deposits are relatively widespread, low in grade (less than 1 % U3O8) but high in tonnage. Although it has been considered that this type of deposit was formed due to hydrothermal alteration unrelated to magmatic activity, the detailed evolution of fluids and ore-forming process are still not well understood. Through element-mass-balance calculation and geochemical mapping of regional rocks, we investigated the Jiling uranium deposit in northwestern China and evaluated the composition and source of fluids and element-transfer behavior through Na-metasomatism and uranium mineralization. The findings show that, in the early Na-metasomatism stage, the Na-, HFSE- and REE-rich late-magmatic hydrothermal fluids caused Na-metasomatism of wall rocks, enriching Na2O (>53 %) while removing K2O (<-78 %), depleting SiO2 (30 % in granite and 3 % in diorite), and massively mass-transferring Fe, Ti, P and some incompatible elements. With increased rock permeability and the formation of partial Fe2+-bearing minerals, the Na-metasomatic alteration produced reducing agents and migration channels for ore-forming fluids, as well as the creation of ∼ 15 vol% porosity in the altered granite for metallogenic space. In the late uranium mineralization stage, CO2-rich fluids extracted uranium and HREEs, converted Fe2+ to Fe3+, and subsequently precipitated uranium to form pitchblende with apatite, calcite and chlorite. Thus, the Na-metasomatic alteration caused by late-magmatic hydrothermal fluids is critical for the production of large Na-metasomatic hydrothermal uranium deposits. Our new geochemical mapping reveals that the mass-concentration changes of Na, K and Si are more credible to defining Na-metasomatic alteration, while Fe, Ti, P, ∑(Zr-Hf-Nb-Ta) and ∑LREE/∑HREE vary strikingly during the uranium mineralization process.