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The Huxu Au-dominated polymetallic deposit is a hydrothermal deposit located in the Dongxiang volcanic basin in the middle section of the Gan-Hang tectonic belt in South China. The orebodies primarily occur within the Jurassic-Cretaceous quartz diorite porphyry, while the genesis of this deposit is unclear. This study focused on geological and mineralogical characteristics, in-situ trace elements and S-Pb isotopes of three generations of pyrite of the Huxu deposit to clarify the distribution of trace elements in pyrite, ore-forming fluid and material sources, and genetic types of the deposit. The mineralization stage of the deposit can be divided into quartz-pyrite stage (S1), quartz-pyrite-hematite stage (S2), quartz-polymetallic sulfide stage (S3) and quartz-hematite stage (S4), with the corresponding pyrite being divided into three generations (Py1–Py3). in-situ trace element data of pyrite show that Au in pyrite mainly exists in the form of solid solution (Au+), and the content is relatively low at all stages (0.18 ppm for Py1, 0.32 ppm for Py2, 0.68 ppm for Py3), while Pb and Zn mainly exist as sulfide inclusions in the pyrite. S-Pb isotopes show that the sulfur and ore-forming material of this deposit are mainly sourced from magma. The mineral association, mineral textures and trace elements in different stages of pyrite indicate that fluid boiling and fluid mixing are the key factors of native gold precipitation in S2 and S4, respectively, while water-rock interaction controlled the precipitation of Pb-Zn sulfides. These integrating with geological characteristics suggests that the deposit should be an intermediate sulfidation epithermal deposit. [ABSTRACT FROM AUTHOR]

The Chayong Cu-polymetallic deposit is a recently discovered Cu-polymetallic deposit hosted in the Sanjiang Metallogenic Belt within the Tibetan Plateau of China to the northeast of the North Qiangtang terrane. The ore body occurs in siltstone and is controlled by a northwest-trending fault structure. According to the associations, assemblages, and cutting relationships between ore veins, the hydrothermal mineralization period can be divided into three mineralization stages: (1) a molybdenite mineralization stage, (2) a Cu-polymetallic sulfide stage, and (3) a quartz-carbonate stage. Two types of fluid inclusions (FIs), namely, liquid and vapor-rich inclusions, are present in quartz associated with sulfide minerals. Early-stage FIs are both liquid and vapor-rich, homogenized at temperatures ranging from 364.1 to 384.2 °C, and have salinities ranging from 0.70% to 9.60% NaCl equivalent (eqv). The middle-stage FIs are also both liquid- and vapor-rich, homogenized at temperatures ranging from 272.4 to 355.6 °C, and have salinities ranging from 0.53%–17.10% NaCl eqv. The late-stage FIs are liquid, homogenized at temperatures ranging from 209.4 to 255.3 °C, and have salinities ranging from 0.35%–6.87% NaCl eqv. The samples from the deposit have δ34S values of − 21.8‰ to − 19.2‰ and − 5.5‰ to − 6.0‰, suggesting that sulfur was derived from the host sediments and magmatic fluids, respectively. The metallic minerals within the deposit have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of 18.439–18.458, 15.656–15.679, and 38.772–38.863, respectively, suggesting that the metals were derived from the upper crust and orogenic belts. The samples from the deposit have δ18OW values of 2.99‰–7.99‰ and δDW values ranging from − 84.4‰ to − 73.9‰, indicating that the ore-forming fluids were magmatic and mixed with minor amounts of meteoric water. The ore-forming fluid of the Chayong copper polymetallic deposit was a high-temperature, medium- to low-salinity H2O–NaCl–CH4–N2 ± CO2 fluid system. The early high-temperature magmatic fluid, due to boiling, decreased in temperature, and via the mixing of meteoric water, gradually evolved towards the later-stage medium- to low-temperature and low-salinity fluid, causing molybdenite mineralization and forming copper polymetallic sulfide veins and quartz carbonate veins. [ABSTRACT FROM AUTHOR]

Jumun Island is tectonostratigraphically situated on the marginal zone of the Gyeonggi Massif. The Massif is in contact with the southwestern margin of the Imjingang Belt and adjacent to Boreum Island, where ultramafic rock with magmatic Fe-Ti oxide deposits occurs. The northwest of Jumun Island, facing the Boreum ultramafic rock with Fe-Ti oxide ores, is composed of Precambrian Boreumdo schists containing a few magmatic intrusives, the exact ages of which are unknown. In Jumun, the ultramafic intrusion (Mg# = 75), which is confined to a narrow zone along the seaside, mainly consists of olivine (Fo = 81–82), amphibole (magnesio-horn-blende to tremolite), and phlogopite. The olivine is strongly serpentinized and encompassed by amphibole and phlogopite. The Ni-Cu sulfide mineralization found in the ultramafic rock is weak but has a typical assemblage of pyrrhotite-pentlandite-chalcopyrite with a small amount of magnetite. Notably, the Ni-Cu sulfides are closely associated with amphibole and phlogopite and are found in the fractures and interstitials of the olivine grains. The pyrrhotite (n = 2) and chalcopyrite (n = 1) are compositionally close to pure samples, whereas the pentlandite (n = 2) is characterized by enrichment with Co (up to 6.9 wt%). The sphalerite-bearing quartz vein cuts across the Precambrian gneissic rock and strikes N70 °W with an 80 °NE dip. This vein, which is traceable to a limited extent and approximately 40 cm wide, shows mineralogical zonation in the inward direction from pyrite to sphalerite-dominant. Consisting of sphalerite, pyrite, quartz, and chlorite with minor amounts of chalcopyrite, pyrrhotite, and pentlandite, it is composed of 9.56 wt% Zn with < 1.0 wt% As, Co, Cu, In, Mn, Ni, and Pb and below-detection limits (0.001 ppm) amounts of Bi, Ge, Mo, Se, Sb, Te, and W. Sphalerite, a principal ore mineral, is coarse-grained and reddish-brown and is composed of 57.3–58.8 wt% ZnS, 8.0–9.2 wt% FeS, and 32.0–32.4 wt% S with small amounts of Cu, Mn, As, and Cd. The recently discovered Ni-Cu sulfide mineralization and quartz vein with sphalerite, along with the linear array of magmatic Fe-Ti oxide deposits, provide conclusive evidence that the marginal zone of the Gyeonggi Massif may be a geologically favorable area for the formation of magmatic and magmatic-hydrothermal deposits. For exploration purposes, it is necessary to contextualize the source, tectonic setting, and magmatic evolution. [ABSTRACT FROM AUTHOR]

Rare metals such as lithium (Li), rubidium (Rb), and cesium (Cs) are strategically crucial mineral resources for the development of emerging industries in China. Ensuring a stable long-term supply of these resources is essential. The geothermal systems in Xizang, China are well-developed, with a wide distribution of various types. Most high-temperature geothermal systems in Xizang are exceptionally enriched in rare metal elements (RMEs) and have the potential to become a new source of rare metals to secure China's strategic mineral resource supply in the future. A close relationship also exists between the geothermal system and the special salt lake resources on the Tibetan Plateau. Geothermal springs thus play a key role in the migration and enrichment of RMEs from deep to shallow parts of the crust, in the transition between endogenous and exogenous mineralization, and source-to-sink processes. However, the mechanisms of element enrichment and evolution in these springs have not been systematically discussed, and many theoretical issues remain to be investigated. Based on summarizing and analyzing previous research, this study employs hydrochemical and isotopic geochemistry methods to investigate typical geothermal springs across Xizang and explore the anomalous enrichment mechanism of RMEs, and the resource effects of geothermal springs. Comprehensive analysis shows that the total dissolved solids (TDS) and hydrochemical types of geothermal springs are similar to those of major geothermal fields worldwide, but the Tibetan springs are abnormally rich in Li (averaging 5.48 mg/L), Rb (averaging 0.75 mg/L), and Cs (averaging 3.58 mg/L), which are hundreds to thousands of times more concentrated than natural waters. The distribution of these enriched geothermal springs is controlled by the Yarlung Zangbo suture zone and the extended N-S trending rifts, especially in the intersection zone of the two, where the geothermal springs are the most enriched. Based on the spatial distribution, isotopic, and elemental geochemistry, the RMEs enriched in Tibetan geothermal springs are mainly derived from the magmatic-hydrothermal fluids generated by the partial melting of the subducted Indian plate under the Eurasian continent. These fluids not only maintain geothermal activities as a heat source but also participate in the material cycle of the geothermal spring as a material source. Against the background of regional crustal enrichment in RMEs, incompatible elements such as Li, Rb, and Cs are gradually enriched in magmatic-hydrothermal processes including partial melting in the source, magmatic differentiation, and hydrothermal fluid exsolution, and some ore-forming elements are further extracted from surrounding rocks through deep high-temperature water-rock interactions. Eventually, an eruption occurs, and these fluids move to the surface to form a geothermal spring rich in RMEs. With the drainage of geothermal springs, the RMEs are continuously transported to the lake basin by surface runoff and continue to concentrate and evolve into salt lake brines under an extremely arid climate environment, constituting an endogenous source and exogenous accumulation salt lake metallogenic model. This comprehensive explanation of the sources, migration, enrichment mechanisms, and resource effects of geothermal springs will deepen the understanding of rare metal mineralization processes, and aid in the advancement of theoretical models for key rare metal mineral resources in various geological bodies of the Tibetan Plateau, significantly expanding exploration scopes and accurately assessing the resource potential of RMEs. [ABSTRACT FROM AUTHOR]

An original database compiled by the authors on volatile components of mineral-hosted fluid inclusions currently includes 12 470 analyses from 480 publications and was used to calculate the average gas phase composition of fluids that formed hydrothermal deposits throughout the Earth's geological evolution, from the Archean to Cenozoic. The paper reviews the methods used in the study, their potential errors, and limitations. Characteristics of the gas composition of fluids are traced for more than 300 ore deposits of Au, Sn, W, Cu, Cu, Pb, Zn, Sb, Mo, and U. The dominant volatile component of natural mineralizing fluids in the Earth's crust is carbon dioxide, regardless of the geologic age. The fluids contain subordinate amounts of reduced carbon species (methane) and nitrogen, as well as minor amounts of hydrogen sulfide and some other gases. The Cenozoic fluids commonly contain more nitrogen than methane. These relations are occasionally also found in the Precambrian fluids. The CO2/CH4 ratio as an indicator of the redox state of the system notably increased over the Earth's geological history. [ABSTRACT FROM AUTHOR]

Te–Bi bearing minerals are commonly present in many hydrothermal gold deposits and can provide important physicochemical constraints on their mineralization. The gold mineralization in the Xiejiagou gold deposit is hosted in the Mesozoic Linglong granite and consists of auriferous quartz veins and subordinate disseminated ores in the vein-proximal alteration zone. Three types of pyrite were identified that formed in stage I, II, and III. Gold occurs mostly as native gold and electrum (Ag > 20 wt.%) inclusions in or filling microfractures in pyrite. The abundant auriferous pyrite-quartz veins contain an assemblage of tsumoite and hessite. The tsumoite occurs as irregular inclusions in the Py1 and is intergrown with the chalcopyrite. The hessite occurs as irregular inclusions or along the margins of the Py2, and it coexists with the gold and galena. The tellurium fugacity continually decreased from stage I (log fTe2 = −8.8 to −10.7) to stage III (log fTe2 = −13.8 to −17.0). The sulfur fugacity increased from stage I (log fS2 = −8.6 to −11.4) to stage II (log fS2 = −7.2 to −11.4), and then, it decreased from stage II to stage III (log fS2 = −9.8 to −13.0). These data indicate the conditions of the gold precipitation during the ore formation process. A detailed study of gold distribution in texturally different pyrite and the paragenetic association of tellurides provide valuable information on the distribution pattern of gold and in understanding the processes of gold deposition and evolution. [ABSTRACT FROM AUTHOR]

This paper presents an integrated approach involving geophysical and remote sensing datasets in the identification of regions that have undergone hydrothermal alteration in the gold-hosted site of the Ife–Ilesa schist belt. Geophysical methods employed include the aeromagnetic and aeroradiometric data, while the remote sensing involved Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Derivatives such as analytic signal, total horizontal derivative, tilt derivative of the total horizontal derivative, and 3-D Euler deconvolution were applied on the aeromagnetic data for the mapping and delineation of structures guiding migration of hydrothermal and mineralizing fluids in the study area. Radiometric analyses involving K/eTh, Ideal K anomalies deviation (Kd), and F-parameter, including principal component analyses on ASTER to isolate Potassic, Argillic, Propylitic, and Phyllic alteration zones were performed to delineate hydrothermally altered zones. The lineament map showed that the study area is geodynamically active as evident by the presence of deep-seated intersecting structures with depths ranging from 189 to 899 m, principally trending NE–SW, which is an impression of the Pan–African orogeny. The fuzzy gamma operator 0.9 was thereafter used in the integration of aeroradiometric and ASTER data for the hydrothermal alteration map production. Subsequently, five classes ranging from background to very high alteration anomalies were derived using the concentration–area (C–A) fractal model from the hydrothermal alteration map. These classes reveal the pervasive styles of alteration in the study area. The study further revealed the close association of structures, granitoids, hydrothermal alteration, and orogenic gold deposits. Also, the flurry of mining activities in the southern flank of the study coincides with most of the hydrothermally mapped areas with the Prediction–area (P–A) plot showing 78% occurrence of orogenic gold deposits in 22% of the total area explored. This translates to high potential of orogenic gold mineralization in the study area. The study therefore concluded based on the validation result that hydrothermal alteration mapping is important in the mapping of orogenic gold deposit. Hence, unexplored areas particularly in the western and eastern flank of the study area where there are strong indications of hydrothermal alteration have good prospect for gold mineralization. [ABSTRACT FROM AUTHOR]

The Wutonggou iron deposit is located in the well-known iron metallogenic belt in the eastern Tianshan, NW China, and has been regarded as a sedimentary iron deposit. Although hydrothermal overprinting could play indispensable roles in the formation of high-grade iron ores in sedimentary iron deposits, previous studies mainly focused on sedimentary-related iron mineralization, while the nature and contribution of hydrothermal fluids are poorly constrained. Accordingly, an integrated study of ore geology, H-O-C isotopes and 40Ar-39Ar dating, is conducted on the Wutonggou deposit, in order to reveal the features, source, and timing of hydrothermal mineralization. The studied deposit includes two mining sections namely the Jianshan and Wutonggou. The δ18O values of early magnetite from the Jianshan section range from +3.0‰ to +5.8‰ that nearly consistent with classic magmatic magnetite, while increase to 6.3‰–8.0‰ in the late stage. Quartz from the two sections shows comparable H-O isotopic compositions and identical fractionation trends, and is plotted in or periphery to the primary magmatic water area. Calcites from the two sections are broadly similar in carbon and oxygen isotopic compositions, and siderite from the Wutonggou section is plotted in the same region. Thus, comparable stable isotopic compositions and evolution trends indicate similar magmatic fluids contributed hydrothermal iron mineralization in the two mining sections. Moreover, water-rock interactions of varying degrees generated distinct mineralization styles in the Jianshan and Wutonggou sections, and caused the isotopic fractionation in late stages. Biotite extracted from a hydrothermal siderite ore yielded a 40Ar-39Ar plateau age of 299.5 ± 2.0 Ma, indicates the timing of hydrothermal iron mineralization is corresponding to the emplacement of vicinity granitoids. Taken together, the hydrothermal mineralization in the Wutonggou iron deposit was the product of remobilization and upgrading of early sedimentary iron ores, and ore-forming fluids were most probably originated from regional granitic magmatism. [ABSTRACT FROM AUTHOR]

Radon (Rn) and helium (He) gases from uranium decay form distinct anomalies related to buried uranium deposits. In order to trace the geochemical anomalous sources from the volcanic-related uranium deposits in deeply buried areas, systematical Rn contents and He isotope ratios were analyzed from the Daguanchang uranium deposit. The soil gas Rn concentrations above the deep uranium are ten times higher than those in barren areas, indicating that instantaneous Rn content measurements can be used to detect deeply buried uranium. The helium isotope ratios (3He/4He) of the unmineralized samples from the mineralized drill hole (ZK1) are relatively lower and uniform compared to those of the samples from no-mineral drill hole (ZK2). However, the Th and U contents of the drill core samples from ZK1 are slightly lower than those of the samples from ZK2, indicating that the lower 3He/4He ratios in ZK1 are most likely due to the addition of 4He from underlying uranium intervals. The differences in the instantaneous Rn contents are consistent with the variations in the He isotope ratios of the drill core samples. These results demonstrate that soil gas Rn and 3He/4He ratios are useful tracers and can indicate the existence of deeply buried volcanic-related hydrothermal uranium ores. [ABSTRACT FROM AUTHOR]

Based on the study of local volumes of minerals using the classical methods of isotope dilution and thermal ionization mass spectrometry (U–Pb ID TIMS), an isotopic study of pitchblende and galena is carried out at the Natali uranium ore occurrence (Northern Transbaikalia). For the first time, it was shown that the pitchblende mineralization at the ore occurrence has a Late Silurian (422 ± 4 Ma) age. Its formation is related to the Early–Middle Paleozoic collisional tectogenesis in the area of the Tonod uplift, accompanied by increased fluid activity. The Pb isotopic composition analysis in galena associated with pitchblende show that galena is enriched in radiogenic isotopes 206Pb and 207Pb, a source of which was ancient (Precambrian) concentrations of uranium. [ABSTRACT FROM AUTHOR]

Hydrothermal disseminated gold mineralization in the Sanshandao gold belt, Jiaodong Peninsula, China, is closely associated with regional NE–NNE fault zones. To investigate the structural controls on this mineralization, we conducted 3D numerical modeling of coupled heat transport, tectonic deformation, and fluid flow, of which two sets of models, designed simple models and actual models, were involved. The simple models were used to examine how general fault geometries (fault bend length, fault bend angle, and fault dip) influenced dilation (positive volume strain) and fluid flow and further influenced hydrothermal mineralization. In contrast, actual modeling was carried out to further understand the structural controls and mineralization localization in a specific geological condition at Sanshandao. Following this, numerical simulation experiments with variable paleo-stresses on these two models were carried out in FLAC3D platform. The simulation results of the simple models showed that long fault bend lengths, large absolute fault bend angles, and large changes in fault dip were more likely to promote dilation in the fault zone. The dilation zones are related to the small intersection angle of maximum principal stress and fault dip. The simulation results of the actual model illustrate that the gold mineralization distribution at Sanshandao was controlled by the coupling of fault strike–dip bends. Specifically, the discontinuous mineralization in the vertical direction was caused by local fluid focusing due to fault dip changes, particularly where the bend length was long. In addition, the oblique orientation of ore shooting depended on the variable strain orientations relative to the fault, which appeared to be fault strike variations. The results further determined the NNW–SSE-directed compression as the paleo-stress regime at Sanshandao during the ore-forming period. Our data also illustrated the deep fluid flow pathways in the Sanshandao gold belt and the Xinli S–SSE deep and the Sanshandao and Beibuhaiyu E–NE deep areas deserve to be the focus of the next gold exploration. [ABSTRACT FROM AUTHOR]

Wastewater treatment is inevitably required to alleviate the pollution of water resources by various contaminants such as antibiotics. MOFs are novel materials with photocatalytic activities. In this study, sonophotocatalytic degradation of tetracycline (TC) by the Cerium-based MOF (Ce-MOF) is optimized by modification of its synthesis route. Ce-MOF synthesis by room temperature (RT), hydrothermal (HT), and sonochemical synthesis (SC) are studied. TC degradation experiments revealed the superiority of SC synthesis. The interplay of main synthesis parameters, namely, initial ligand concentration, ultrasound (US) power and time on sonophotocatalytic activity of Ce-MOF, were investigated by response surface methodology model (RSM) utilizing the central composite experimental design (CCD). The optimum SC synthesis conditions are an initial ligand concentration of 8.4 mmol/L, a sonication power of 50 amplitude, and a US time of 60 min. The optimally synthesized Ce-MOF was characterized by infrared spectroscopy, FTIR, XRD, FE-SEM, TEM, zeta potential analysis, diffuse reflectance spectroscopy, particle size analysis, Mott-Schottky analysis, photocurrent analysis, electrochemical impedance spectra, and photoluminescence spectroscopy. The findings indicate that the removal efficiency of TC can reach up to 81.75% within 120 min in an aqueous solution containing an initial TC concentration of 120 ppm and 1 g/L Ce-MOF at pH of 7. Mineralization efficiency of the process is 71% according to COD measurements. The Ce-MOF catalyst retained its chemical stability and remained active upon TC degradation which makes it a promising candidate for wastewater treatment. [ABSTRACT FROM AUTHOR]

The estimation of the degree of tectonic fragmentation for upper lithosphere following the method of Yu.V. Nechaev (2010) is based on calculations of specific lineament lengths. We used data for three regions—Northwest Caucasus, the Voronezh Anteclise, and the Malko–Petropavlovsk zone in Kamchatka—to test whether other morphometric parameters could be used: specific lengths of "weak" zones, elongation lines and water streams, as well as relief curvature. Their anomalies are confined to seismic areas and to areas of hydrothermal and magmatic activity. We show that the most information is provided by 3D models of tectonic fragmentation that incorporate specific lengths of "weak" zones and water stream lengths. [ABSTRACT FROM AUTHOR]

To separate oil–water mixtures especially in oil field operations, new energy-efficient methods are urgently required. Conventional separation techniques using demulsifiers for separation of oil–water mixtures or even use of membranes usually suffered from high cost and energy consumption, composition dependency of demulsifiers and fouling or inability of a single membrane to separate all types of oil–water mixtures. This research aimed to synthesize tungsten oxide-coated stainless steel mesh using the hydrothermal method, with a focus on evaluating its effectiveness in oil–water separation. The coating procedure was carried out using hydrothermal techniques, with an emphasis on investigating the impact of precursor concentration, pH levels, reaction temperature and duration, on the separation efficiency of the optimal coating solution. The hydrothermally coated stainless steel mesh was created within a polytetrafluoroethylene reaction vessel, submerged in a 150 ml aqueous solution containing 0.0094 mol of sodium tungstate di-hydrate at pH 3.0, achieved through the addition of hydrochloric acid. Additionally, 1 g of oxalic acid, acting as a chelating agent, was introduced. Subsequently, the mesh underwent a 4 h reaction at 220 °C and was subsequently annealed for 30 min in a 350 °C furnace. Remarkably, the resultant mesh exhibited an exceptional water separation flux of 9870 ± 15 L/hr/m2 when exposed to 1:1 v/v oil–water mixtures. This performance significantly outperformed previous filters designed for similar oil–water separation tasks. The mesh efficiently facilitated the passage of water through the oil–water mixture, achieving an efficiency rate exceeding 98 ± 1%. To gauge its wetting behavior, the hydrophilic/underwater oleophobic filter underwent static contact angle measurements. The filter's wetting mechanism was primarily attributed to its hierarchical surface structure, which enhanced surface hydrophilicity and roughness. Analytical techniques such as XRD, FTIR, and FE-SEM were employed to scrutinize the fabricated filter's composition. These analyses confirmed the successful creation of a nanostructured WO3 coating on both sides of the stainless steel mesh. Moreover, the utilization of commercially available chemicals and straightforward fabrication techniques underscores the promising potential of this approach for large-scale applications. [ABSTRACT FROM AUTHOR]

Thermochemical transformations of the organic matter and mineral matrix of the bituminous oil-containing rock from the productive stratum of Permian heavy crude deposits (Ashal'cha oilfield) at 350 and 600°С in a hydrogen medium were studied by electron paramagnetic resonance (EPR) spectroscopy. A rock sample taken from a depth of 117.5–118.5 m was studied before and after hydrothermal treatment at 300°С in the presence of an aqueous phase. Comparison of the EPR spectra shows that, as compared to the initial rock, an increase in the temperature to the "oil window" level, 350°С, leads to a fourfold increase in the intensity of the signal from free organic radicals (С350), and after hydrothermal treatment its intensity increases by a factor of 5. This fact characterizes the oil-generation potential of the rock with the formation of liquid and gaseous hydrocarbons. On reaching the "oil and gas window" temperature (600°С), organic carbon radicals (С600) were not detected. This fact suggests that the rock from productive deposits of the Permian age virtually completely realizes its oil-generation potential at 350°C. The amount of Mn2+ ions in calcite after the hydrothermal treatment gradually decreases with an increase in the pyrolysis temperature. Iron oxides and hydroxides were detected as concomitant compounds. They can exhibit catalytic properties in hydrothermal and pyrolytic processes. The presence of minerals of iron and manganese in different oxidation states suggests nonequilibrium conditions of the rock alteration. Thus, EPR can serve as a nondestructive method for simultaneous monitoring of the mineral composition and organic matter of rocks. [ABSTRACT FROM AUTHOR]

The Yueguang gold deposit is located in Fengjia, Xinhua County, Hunan Province, South China. It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt, west of the Baimashan granitic batholith. In order to discern the characteristics of the ore-forming fluids, the underlying mineralization processes, and establish a foundation for the origin of the Yueguang gold deposit fluid inclusion microthermometry, as well as quartz hydrogen and oxygen isotope analysis, have been carried out on samples obtained from various stages of mineralization. The hydrothermal mineralization stages within the Yueguang gold deposit can be categorized into three stages: (i) the barren, pre-ore quartz-pyrite stage (Stage I), the quartz-pyrite-gold stage (Stage II), and the post-ore quartz-carbonate stage (Stage III), with the second stage being the main mineralization stage. The fluid inclusions identified in samples from the main mineralization stage can predominantly be described with the NaCl–H2O and CO2–NaCl–H2O systems. These inclusions display homogenization temperatures ranging from 158.8 to 334.9 °C, and the fluid salinity ranges from 0.3% to 4.0% (wt.% NaCl equiv.). Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO2, CH4, and N2. Isotopic analysis indicates δ18O fluid values ranging from 3.95 to 6.7 ‰ and δDH2O values ranging from − 71.9 to − 55.7 ‰. These results indicate that the ore-forming fluid of the Yueguang gold deposit belongs to metamorphic hydrothermal fluids of middle-low temperature and low salinity. In the process of ore formation, gold is transported in the form of Au (HS)2− complexes, with gold deposition being driven by fluid immiscibility. Therefore, the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrothermal fluid. It may become a new target for gold exploration in the Baimashan region, central Hunan Province. [ABSTRACT FROM AUTHOR]

Through our monitoring of the volcanic characteristics of well waters around Usu Volcano, Hokkaido, Japan, we evaluated the relationships among dissolved carbon dioxide (D-CO2), water temperature and pH in the Toya-ko and Sobetsu hydrothermal areas in 2000–2020 after the most recent eruption. The D-CO2 concentrations of sampled waters from wells connected to the hydrothermal areas increased in 2000–2006 and decreased thereafter until 2020. The water temperature continued to fall from 2000 to 2010, and fell moderately further until 2020. The pH was constant from 2000 to 2015 and rose thereafter. Scatter diagrams were drawn with D-CO2 concentration per unit water temperature on the x axis and D-CO2 concentration per unit pH on the y axis for water samples from 12 to 16 wells each year. The approximate formula was represented as z = ax + by from the scatter diagrams using the principal component analysis. The value of b/a was predicted to have a high value for well water groups in the volcanic hydrothermal areas. The values of a, b and b/a might be applicable as distinct factors for volcanic or non-volcanic hot water based on the examples of 7 well water groups in the various hydrothermal areas. The b/a values rapidly decreased from 2000 to 2003 and showed a further decrease until 2020 for the well waters from the Toya-ko and Sobetsu hydrothermal areas. This suggests that the groundwater with no volcanic reaction increased in the well water. [ABSTRACT FROM AUTHOR]

This paper examines the Karymsky Volcanic Center to estimate how much volcanic and hydrothermal activity affects the chemical composition of river water. We evaluate the volumes of major and trace elements coming to the Pacific Ocean via the Karymsky River. We assess the quality of river water in compliance with the regulations for potable water, water used for household work, and in fisheries. It is shown that the formation of ion load of the river water mostly occurs by inflow of thermal waters, as well as due to water-soluble complexes of ashes discharged by Karymsky Volcano and coming to the catchment area of the river. The annual volume of dissolved material transported by the river to the Kronotsky Bay of the Pacific Ocean amounts to more than 90 kilotons. [ABSTRACT FROM AUTHOR]

Magma intrusion has an important influence on the physical and mechanical properties of coal and rock. In the area of magma intrusion, disasters such as gas outburst are prone to occur. Revealing its invasion law will be conducive to disaster management and energy development. For this purpose, changes in industrial analysis components of coal, mineral composition, major oxides, trace elements, and rare earth elements of coal under the thermal metamorphism of magma intrusion were analyzed. It is found that the moisture and volatile matter contents of the thermally affected coals in the mining face are generally lower than that of normal coals, while moisture and volatile matter contents are reduced towards to the magma intrusion contact. For example, the moisture and volatile matter of coal sample M01 decreased by 64.6% and 38.6% respectively compared with coal sample M05. During magma intrusion, some minerals remain on the surface of the coal body, resulting in changes in the mineral composition of the coal body. The decrease in carbon atom net spacing, the increase in crystallite aggregation and ductility, and aromaticity in thermally affected coals have a positive impact on the improvement of coal metamorphism. Due to the influences of magmatic intrusion, the variation rules of major oxides in coal are different, and the closer to the magmatic intrusion zone, the easier the major oxides are to be depleted. However, magma intrusion will not lead to the loss of all major oxides in thermally affected coals, such as content of CaO is 54.8%, which is higher than that of coal not affected by magmatic hydrothermal fluid. Most of the trace elements in the thermally affected coals of the No. 9 coal seam are depleted. The contents of rare earth elements are low on the whole coalbasis, with an average of 29.48 μg/g, and the distribution pattern towards to magmatic intrusion shows a wide and gentle "V" curve with left high and right low, showing the characteristics of enrichment of light rare earth elements. [ABSTRACT FROM AUTHOR]

This paper reports the efficiency of photocatalytic process activated under hydrothermal conditions. This hybrid activation is efficient for effluent treatment at relatively low temperature (below 150 °C) and pressure (5 bar) in presence of TiO2 containing anatase phase alone or in mixture with rutile. We compared the efficiency of this hybrid process in regards to photocatalysis at ambient temperature and to catalytic oxidation under mild pressure and temperature (hydrothermal process) by investigating the impact of temperature (90–150 °C), irradiation type (UV-A centered at 365 nm and visible light [λ > 400 nm]) and nature of TiO2 (anatase, rutile or mixture of anatase and rutile) on the conversion and mineralization of glucose. This hybrid process (photocatalysis assisting by hydrothermal process) showed better mineralization of glucose than the two separated processes explained by a more important formation of hydroxide ions by hydrothermal process favoring HO° radical by photocatalysis. This new process was also efficient for industrial effluent mineralization. [ABSTRACT FROM AUTHOR]

The Zhazixi deposit hosted in sedimentary rocks is a major Sb-W deposit in South China. The mineral scheelite, which can be dated by the U-Pb method, commonly occurs in both tungsten (W)-dominated and antimony (Sb)-dominated ore veins of the deposit. Cathodoluminescence (CL) images reveal the presence of three distinct stages of scheelite (Sch-I, Sch-II and Sch-III) within the deposit. These three scheelites were dated using in-situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), yielding U-Pb ages of 158.1±5.4 Ma and 157.6 ± 4.9 Ma for Sch-I, 155 ± 11 Ma for Sch-II, and 151.3±6.1 Ma for Sch-III. These data suggest that the Zhazixi Sb-W deposit formed during the Late Jurassic (160–150 Ma) rather than the Late Triassic as previously suggested. Considering the temporal similarity with low-temperature hydrothermal Sb deposits in the Xiangzhong metallogenic province (XZMP), the formation of the Sb-W deposit may have followed a similar genetic model, where meteoric groundwater circulated to depth and extracted metals from fertile basement rocks through fluid-rock interaction, resulting in the generation of ore fluids. This study highlights that Late Jurassic low-temperature hydrothermal Sb-polymetallic mineralization in the XZMP is likely more extensive than previously perceived. [ABSTRACT FROM AUTHOR]

In this work, we investigated in situ isotopic compositions of antimony (Sb) minerals from two substages of the ore deposits near Pezinok (Slovakia). The δ123Sb values of the primary Sb minerals range from −0.4 and +0.8‰ and increase progressively along the precipitation sequence. In the substage II, the early-formed gudmundite (FeSbS) shows in all sections the lowest δ123Sb values, followed by berthierite (FeSb2S4), stibnite (Sb2S3), and valentinite (Sb2O3) with the heaviest δ123Sb values. A similar trend was observed for the substage III, from the initially-formed stibnite, followed by kermesite (Sb2S2O), valentinite, senarmontite (both Sb2O3), and schafarzikite (FeSb2O4). The evolution can be rationalized by a Rayleigh fractionation model with a starting δ123Sb value in the fluid of +0.3‰, applying the same mineral-fluid fractionation factor to all minerals. Thus, the texturally observed order of mineralization is confirmed by diminishing trace element contents and heavier δ123Sb values in successively crystallized Sb minerals. Antimony in substage III was likely supplied from the oxidative dissolution of stibnite that formed earlier during substage II. The data interpretation, although limited by the lack of reliable mineral-fluid fractionation factors, implies that Sb precipitation within each substage occurred from an episodic metal precipitation, likely associated with a similar Sb isotope fractionation between fluid and all investigated Sb minerals. Large isotopic variations, induced by precipitation from a fluid as a response to temperature decrease, may be an obstacle in deciphering the metal source in hydrothermal ore deposits. However, Sb isotopes appear to be an excellent instrument to enhance our understanding on how hydrothermal systems operate. [ABSTRACT FROM AUTHOR]

The oblique distribution of orebodies is a basic feature of the spatial distribution of orebody groups in hydrothermal deposits, and it is closely related to the shearing effect. However, the oblique distribution patterns of orebody groups controlled by ore-controlling/ore-forming structures at different scales (orebody, ore deposit and ore field scales) and the underlying formation mechanism are unclear but could be used to directly constrain mineral exploration and prospecting breakthroughs in the deep and peripheral areas of ore deposits. This paper uses the northeastern Yunnan Ge-rich Pb–Zn ore concentration area in the Sichuan–Yunnan–Guizhou metallogenic area as an example to analyse and demonstrate the oblique distribution patterns of orebodies (orebody groups) controlled by ore-forming/ore-controlling structures at different scales and the underlying mechanical model based on the Theory and Methods of Ore field Geomechanics. The results indicate that in 3D space, the oblique distributions of orebodies (veins), orebody groups and ore deposits are controlled by the mechanical properties, kinematic characteristics, and tectonic stress fields of ore-forming/ore-controlling fault structures of different sequences during the mineralization period. This study has an important guiding role for ore field-scale exploration deployment, evaluation of deep and peripheral prospecting, and exploration project arrangement, with the aim of helping mining companies increase resource reserves and production. [ABSTRACT FROM AUTHOR]

Pyrite, the most common sulfide mineral, is a ubiquitous component of many hydrothermal gold deposits. Geochemical patterns within the refractory pyrite structure represent a valuable repository of information that can help constrain the sources of ore-forming materials, and the evolution of ore-forming processes over time. However, there are still a lot of debates on the mechanisms of physico-chemical processes in ore-forming fluid controlling trace element and sulfur isotope distributions in pyrite during growth. In our manuscript, we use cutting-edge complementary microanalytical methods to understand the origin and evolution of zoned gold-bearing pyrite in samples from the largest gold deposit in the Ailaoshan gold belt, SW China, Zhenyuan (exceeding 100t Au, average grade: 5.3 g/t). Pyrite, arsenopyrite, chalcopyrite, and stibnite are the most abundant sulfide minerals in most orebodies. Of these, pyrite is dominant and is also the most important host for gold. Two types of pyrite can be clearly distinguished: framboidal pyrite and hydrothermal pyrite. Gold is most commonly hosted by hydrothermal pyrite. Framboidal pyrite, mainly hosted by carbonaceous slate, hosts negligible Au, and features low δ34S values ranging from − 35.0 (± 0.9) to − 25.6 (± 1.0)‰. Hydrothermal pyrite is characterized by complex intra-grain zoned textures with alternating As-rich and As-poor bands readily recognizable on backscattered electron images. Scanning electron microscopy and trace-element analyses show that both visible and invisible gold occur only in the As-rich bands. Compared to the As-poor bands (72.1% of Au concentration data < 1.96 ppm, n = 43), the As-rich bands are characterized by far higher concentrations of Au (up to 1420 ppm), Cu, Ag, Sb, and Tl, but lower concentrations of Co and Ni. In-situ sulfur isotope analysis indicates that the δ34S values of As-rich zones range from − 7.3 (± 0.6) to 2.9 (± 0.6)‰ and are similar to those of As-poor zones (from − 6.9 (± 0.7) to 2.8 (± 0.6)‰), but distinct from the framboidal pyrite. Combined with published fluid inclusion data and a probable age for the magmatic event associated with mineralization, these data suggest that magmatic–hydrothermal fluids contributed most ore-forming materials and that periodic boiling led to formation of the rhythmic As-rich and As-poor bands in pyrite. Our data for pyrite constrain the evolution of ore-forming processes and provide new insights into the formation of zoned pyrite, with the conclusions having broad implications for analogous hydrothermal gold deposits worldwide. [ABSTRACT FROM AUTHOR]

The southeastern French Massif Central represents an ideal area to study the linkage between regional metamorphism, crustal partial melting, emplacement of granitic magmas, and hydrothermal Sn-W mineralization in a polyphase tectono-metamorphic setting related to the late-Variscan orogeny. Here, we describe the mineralogical, structural, geochemical, and geochronological characteristics of cassiterite–wolframite-bearing quartz veins at St-Mélany, a small uneconomic Sn-W occurrence located in the North Cévennes area. The veins show evidence of ductile deformation (boudinage, asymmetric folding, dynamic recrystallization) consistent with a synkinematic emplacement during the regional low-pressure–medium-temperature metamorphism at ca. 320–315 Ma. This dominantly water-fluxed melting event reaching muscovite breakdown conditions (T < 750 °C, P ≈ 0.6 GPa) was synchronous to the emplacement of the syntectonic Rocles peraluminous granite, which is interpreted as a proximal source for the mineralizing fluids at St-Mélany. The U–Pb LA-ICP-MS dating of coexisting wolframite and cassiterite from a mineralized quartz vein yielded lower-intercept ages of 318.4 ± 2.2 Ma and 311.4 ± 1.0 Ma (2σ), respectively. These results suggest a temporal decoupling of W and Sn mineralization with a time gap of 4–10 Myr, but additional work is needed to confirm this interpretation. A weighted mean 40Ar/39Ar date of 304.5 ± 4.8 Ma (2σ) was obtained for muscovite from the selvage of a mineralized vein, interpreted as a recrystallization age related to metamorphic re-equilibration or hydrothermal overprinting. Dikes of aplites and pegmatites cut the Sn-W-mineralized veins and were emplaced at 305.9 ± 3.9 Ma (2σ) based on U–Pb LA-ICP-MS dating of magmatic cassiterite. The dikes have highly evolved compositions typical of peraluminous high-phosphorus rare metal granites with Li-F-Ta > Nb-Sn-Be enrichments. Emplacement of the granitic dikes was coeval with the regional low-pressure–high-temperature metamorphism at ca. 305–300 Ma, reaching biotite dehydration melting conditions (T > 800 °C, P ≈ 0.4 GPa), which led to the formation of the Velay anatectic dome possibly linked to lower crust granulitization. We conclude that polyphase emplacement of W-Sn-mineralized veins at ca. 320–310 Ma and rare metal granitic dikes at ca. 305 Ma results from contrasting crustal melting conditions, in relation to the late-Carboniferous orogenic evolution of the southeastern French Massif Central, and possibly related to delamination of the subcontinental lithospheric mantle. [ABSTRACT FROM AUTHOR]

This work is aimed at the practical application of satellite imagery data for the selection of promising areas during geological exploration work in conditions of medium-low mountainous terrain and a sharply continental climate. The processing results and analysis of WorldView-2 data within the Talmanskaya area are presented in order to identify zones of hydrothermal-metasomatic changes in rocks that are promising for identifying of gold-polymetallic mineralization. The choice of the study area is due to sufficient geological knowledge and the absence of man-made formations that affect the result of processing satellite imagery materials. To increase the spectral information content of the WorldView-2 data, the spectral channel ratio method was used, as a result of which a pseudocolor RGB composite was created that displays the spectral characteristics of objects on the Earth's day surface, in particular, minerals of the oxide/hydroxide group containing transition iron ions (Fe3+ and Fe3+/Fe2+). A comparison of satellite data processing results along with geological information made it possible to identify spectral anomalies as indicators of the presence of near-ore changes, which are an important search criterion for hydrothermal deposits. [ABSTRACT FROM AUTHOR]

This article presents the results of a comparative analysis of the isotopic–geochemical composition of gases from igneous/hydrothermal and sedimentary volcanic systems in various regions of the world based on a large amount of literature data and the results of the author's own research. The purpose of the study is to evaluate the nature of gases of various volcanic systems using known genetic criteria developed as a result of many years of research by a number of scientists from around the world. Data processing for the purpose of comparative analysis and corresponding graphical constructions have been performed using standard computer programs. A comprehensive analysis of the isotopic composition of carbon-rich gases and the isotopic ratio of helium (R/Ra) allows us to draw the following main conclusions: (1) hydrocarbon (HC) gases of the studied volcanic systems have different genetic sources: (a) abiogenic in igneous and carbonic sedimentary volcanic systems, (b) predominantly abiogenic–biogenic in the hydrothermal system, and (c) biogenic (thermogenic–microbial) in sedimentary volcanoes; (2) the content of abiogenic methane in the magmatic/hydrothermal system is insignificant and does not exceed 1%; (3) the isotope composition of CO2 and the ratio of isotopes of radiogenic and air argon (40Ar/36Ar) in igneous volcanoes varies within very narrow limits when compared with sedimentary volcanoes. However, the use of these parameters as an unambiguous genetic criterion is not possible. [ABSTRACT FROM AUTHOR]

Upper Paleozoic (D3–P1) carbonaceous shales and siltstones in the surrounding of the Kara astrobleme are studied. The material composition of the target rocks is analyzed by methods of multidimensional statistics—correlation, factorial, and hierarchical cluster methods. As a result, we revealed the geochemical specificity of the components, generally indicating the contamination of the target rocks of the Kara astrobleme by some ore and rare earth elements by the post-impact hydrothermal activity, mobilization, redeposition, and concentration of the substance. The analysis of the contents of Ni, Cr, and Co indicates partial enrichment of the target rocks by cosmic matter in the area of intense impact crushing, disintegration, and hydrothermal mineralization. [ABSTRACT FROM AUTHOR]

In the process of double-shield TBM excavation, it is difficult to directly observe and test the characteristics of the surrounding rock. In this paper, the screening test of the different type tailings in the wet state was carried out to obtain the gradation curve and curve evaluation index. Combining with the excavation parameters and the surrounding rock characteristics of the tailings, a comprehensive analysis was carried out to establish the evaluation system among with the tailings gradation characteristics, lithology characteristics and excavation parameters. The results showed that: Sparsely fissured rock: the tailings are extensional fractures, the tailings gradation curve is inverse "S" type and gentle, and the evaluation index value: (1.50 > lg(Cu) > 1.35), (1.90 > Cc > 1.10). Broken surrounding rock: the curve is "L" type and steep, the content of coarse particles is much more than that of fine particles and (1.10 > lg(Cu) > 1.00), (2.60 > Cc > 2.40). Fractured rock: the curve is "Step" type, the tailings particles lack the middle particle size, the minerals are mostly weathered, (2.15 > lg(Cu)> 1.95), (0.09 > Cc > 0.07). The research results have good applicability to the surrounding rock stability evaluation of the example tunnel, which verifies the feasibility of the method. [ABSTRACT FROM AUTHOR]

Mica exhibits a relatively high Rb/Sr ratio and possesses a closure temperature for the Rb-Sr isotope system that is higher than the ore-forming temperature range of low- to medium-temperature deposits. Consequently, utilizing the laser ablation (LA) technique for in situ Rb-Sr dating in mica constitutes a significant methodology for resolving the mineralization chronology of low- to medium-temperature hydrothermal ore deposits. In this study, we employed a combination of a triple quadrupole inductively coupled plasma mass spectrometer (ICP-MS/MS) and 193 nm LA system with SF6 as the reaction gas to achieve interference removal of 87Rb+ on 87Sr+. We then developed an in situ Rb-Sr dating method for mica. In addition, an investigation was conducted to identify the factors that could influence the analytical accuracy of the method. Subsequently, we applied the developed method to carry out in situ Rb-Sr dating for the ZBH-25 biotite, a national primary reference material (GBW04439) for K-Ar dating, and yielded a younger age (ca. 12%, relative standard deviation, RSD) than the reference K-Ar age when using NIST SRM 610 as the reference material for external calibration. This finding indicated that in the process of determining Rb-Sr ages for mica by LA-ICP-MS/MS, there are significant matrix effects between the NIST SRM 610 and the mica samples, resulting in inaccurate Rb-Sr ages. In response to this issue, a two-step calibration method is proposed here. Based on external calibration using NIST SRM 610, ZBH-25 biotite is employed as a second external reference material to perform a second calibration of the sample data to correct the matrix effect between the glass standards and the natural mica samples, thereby improving the accuracy of Rb-Sr dating by LA-ICP-MS/MS. Using the proposed method, in situ Rb-Sr dating by LA-ICP-MS/MS was performed on mica samples from monzonite exposed in Mt. Dromedary, New South Wales, Australia, porphyritic granodiorite in Fangshan pluton and albionite granite in the Gyirong area of Tibet. The obtained Rb-Sr age results show agreement with the recommended values within the analytical uncertainty, which serves to validate the accuracy and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The current work is an attempt to reveal the possible utilization of the radiometric measurements to build-up a complete genetic scenario for magmatic, hydrothermal, and supergene uranium mineralization. For this purpose, ground gamma-ray survey was performed through the exploratory tunnels dug perpendicular to El-Missikat and El-Erediya shear zones, the Central Eastern Desert of Egypt. Contents of U, Th, and K were measured for the host pink granite (e.g., avg.15.94 U ppm, 35.62 Th ppm, and 6.63% K), alteration zones (brecciation, silicification, greisenization, kaolinization and hematitization) (e.g., avg. 124.01 U ppm, 63.67 Th ppm, and 3.13% K), and mineralized silica veins (e.g., avg. 312.65 U ppm, 92.22 Th ppm, and 2.62% K). All of these data were graphically represented as correlation plots of Th vs. U, Th/U vs. U, Th vs. K, and U/K vs. Th/K. The overall results indicate magmatic, hydrothermal, and supergene sources of El-Missikat and El-Erediya U mineralization. The magma-derived U contents are enclosed mainly in the pink granite that is mostly characterized by normal Th/U (2.5–5) and Th/K ratios (3–5*10–4). The hydrothermal processes through the alteration zones and mineralized silica veins are reflected by the weak correlation of Th with U (e.g. r = 0.13 and − 0.39), the strong negative correlation of Th/U ratio with U (e.g. r = − 0.82), 2.5˃Th/U˃0.1, Th/K˃5*10–4, Th/K < 3*10–4, and the strong positive correlation of U/K with Th/K (e.g. r = 0.91) as well as the occurrence of thorite, columbite, xenotime and hydrothermal zircon (0.5 > Th/U ≤ 0.1). Afterwards, the hydrothermal mineralization underwent some degrees of chemical weathering that resulted in supergene U mineralization whose fingerprints can be traced by the occurrence of secondary U minerals (e.g. kasolite and uranophane), Th/U ratios ≤ 0.1, and the weak correlation between Th/K and U/K (e.g. r = 0.39 and − 0.11). [ABSTRACT FROM AUTHOR]

The largest tungsten deposit at Degana in NW India, hosted in Neoproterozoic (ca. 827±8.2 Ma) peraluminous granite emplaced within Delhi meta-sediments, characterized as vein and greisen types hydrothermal multi-metal deposit. A number of NW-SE trending quartz and pegmatite veins, intruded in granite, host tungsten and lithium of economic significance. Extensive mining for tungsten ore in the past resulted in huge amount of tailing dumps on hill slope of Rewat hill all over. These tailing dumps mainly contain greisenised granite, pegmatite and quartz-mica-wolframite veins which host anomalous W-Li-Sn-Mo-Ta multi-metals. In this study, we provide first-hand information on W-Li and associated rare metals potential of tailing dumps of Rewat hill using petrographic study and geochemical analysis. A total 7 samples from tailing dumps were analysed by ICP-MS indicate significant W values which ranges between 201.47 ppm to 2647.83 ppm with an average of 748.51 ppm, Li (1006.92 ppm to 6701.43 ppm, avg. 2743.64 ppm), Sn (22.77 ppm to 438.87 ppm, avg. 96.49 ppm), Mo (3.43 ppm to 254.21 ppm, avg. 63.0 ppm) and Ta up to 53.09 ppm. Ore beneficiation study on tungsten ore from tailing dumps by NML indicated that at 5% WO3, the grade of the pre-concentrate; a recovery of > 60% could be achieved whereas at 30% WO3 grade the recovery is about 46%. However, IBM results indicated a recovery of 59.8% with 66.30–66.50% WO3 grade of final concentrate from tailing dumps having assay value between 0.14%–0.15% WO3. [ABSTRACT FROM AUTHOR]

The formation of many hydrothermal gold deposits is closely related to iron-rich rocks. The host rocks of the Madiyi Formation of the Mid- to Late Neoproterozoic Banxi Group for the Woxi Au (-Sb-W) deposit, which is located in western Hunan Province of the western Jiangnan Orogen, South China, is rich in hematite, which provides a good example for studying the relationship between the formation of gold deposit and iron-rich rocks. Field investigation and petrographic observation on the unaltered, weakly altered and strongly altered rocks demonstrate that the bleaching is caused by a combination of carbonatization, sulfidation and sericitization. Mass balance calculation suggests that, during decolourization there is no change in TFe2O3, while FeO is gained and Fe2O3 is lost. Geochemical modeling found that Au was mainly present as AuHS(aq) and Au(HS)2−, and that the water-rock interactions decreased the sulfur fugacity which destroyed the stability of such aqueous complexes. Combined with the locally occurred native gold in quartz veins, it is concluded that the major gold precipitation mechanisms are sulfidation and fluid boiling. Based on previous geochronological and geochemical research further gold mineralization is proposed to be generated by deep sourced magmatic or metamorphic fluid migrated upward along the Woxi fault, and the iron-rich Madiyi Formation is the idea chemical trap for gold deposition. The decrease of sulfur contents caused by fluid-rock interactions and fluid boiling are the major mechanisms for gold mineralization. [ABSTRACT FROM AUTHOR]

This paper considers the conditions of formation for dominantly silver mineralization in the Kyplatap Volcanic Field (KVF), the Chaun Zone, the Central Chukchi Sector, and the Okhotsk-Chukchi Volcanogenic Belt (OChVB). New data are provided for the composition, distribution, and concentrations of trace elements, including REEs, in ore-bearing metasomatites. Appreciable enrichment of the samples in REEs, the dominance of light lanthanoids over heavy ones, very low Eu/Sm ratios (), and low slopes of the near-chondrite spectra involving obvious europium minima, are all typical of the KVF epithermal mineralization system. The values of Ce/Ce* vary between small negative and moderate positive values (between 0.81 and 1.38), while Eu/Eu* varies between 0.28 and 0.7. This combination of Ce/Ce* and Eu/Eu* indicates oxidizing conditions that prevailed during mineralization. The results of thermometric and cryometric studies in fluid inclusions in quartz revealed the fact that the ore-forming fluid contained chlorides of Na, Mg, and K, the epithermal mineralization was deposited by homogeneous hydrothermal fluids with salt concentrations (0.3–6.2 wt %-equi. NaCl), fluid density 0.60–0.87 g/cm3, at temperatures of 203 to 343°С, with the steam pressure varying between 40 and 140 bars. These geochemical and thermometric data corroborate our previous hypothesis, viz., that this KVF mineralization belongs to an intermediate sulfidation epithermal class. These data indicate andesite magmas and meteoric waters as the most likely sources of the fluids. The information reported in this paper is of practical significance for regional predictive metallogenetic constructions, search for and estimates of epithermal Au–Ag deposits. [ABSTRACT FROM AUTHOR]

Prospectivity models that quantify spatial associations between predictor variables and mineralization are critical in data-driven mineral prospectivity mapping (MPM). The current prospectivity modelling approaches, however, are limited in terms of meeting both nonlinearity and interpretability, which are two essential factors in evaluating the performance of a model. Along these lines, this work proposed a novel Bayesian decomposition modelling (BDM) method with nonlinear ability and without loss of interpretability. Following the "decomposition-integration" strategy, the BDM method first decomposed the predictor variables by dimension and then transformed them through nonlinear mapping functions (NMFs). All nonlinear mappings of the predictor variables were then linearly integrated to generate the prospectivity model. Throughout the process, the interpretability of the model was maintained via the decomposition of the predictor variables, and the introduction of NMFs ensured better predictive performance compared to methods that only use linear transformations, such as logistic regression and weights of evidence. The BDM method was applied to the Dayingezhuang deposit, a structurally controlled hydrothermal gold deposit in the Jiaodong Peninsula. The results demonstrate that the area under the receiver operating characteristic curve for the classification model was 0.97, and the coefficient of determination of the gold grade predicted by the regression model was 0.91, clearly indicating that the BDM method possesses excellent predictive ability compared to that of several well-known approaches. Moreover, the classification and regression coefficients of the BDM reveal favourable conditions for gold mineralization in Dayingezhuang, including the negative distance (footwall of fault), gentle dip angle, negative divergence of fluid (mineral fluid convergence) and positive volumetric strains (dilation space). Therefore, the proposed BDM method, which combines robust predictive capability and interpretability, is an effective new method for MPM. [ABSTRACT FROM AUTHOR]

The regolith-hosted rare earth element (REE) deposits in the Nanling Mountain Range, South China, are the most important source of heavy REE (HREE) in the world. A perplexing thing is that only a few of these deposits are relatively enriched in HREE and most of them are actually light REE (LREE)-enriched, although they are all originated from the granitic bedrocks with similar HREE concentrations. This is supposed to be related to the redistribution of REE in the weathered bedrocks due to groundwater-rock interaction, however, it remains enigmatic how REEs are mobilized and fractionated in the interaction. Titanite is an important REE contributor to the regolith-hosted REE deposit. Here, we investigate textural and compositional variations of the titanite from the granitic bedrocks to weathered profiles in the Zuokeng regolith-hosted REE deposit, the largest one that is newly discovered in this region. Together with thermodynamic modelling, we deduce the nature of the fluids, temperature range for titanite alteration, and the mechanism of REE fractionation. Primary titanite is of magmatic in origin and shows relatively high REE contents and negative Eu anomaly on the chondrite-normalized REE pattern. Secondary titanite is commonly associated with chloritized biotite and is characterized by extremely low REE, high Al2O3, F and significant positive Eu anomaly, typical of authigenic origin due to chloritization of biotite under oxidized conditions in supergene environment. From the bedrocks upward to the surface, primary titanite is gradually replaced by calcite, synchysite-(Ce) and TiO2 in the weathered bedrocks. This is interpreted as the result of infiltration of the F, carbonate-rich, alkaline fluids derived from local groundwater through the bedrocks. The irregular dark patches in primary titanite display typical alteration texture and may have formed through fluid leaching of primary titanite. The patches in primary titanite have lower REE concentrations and higher LREE/HREE ratios than magmatic domains, indicating that the groundwater preferentially scavenges HREE from primary titanite, leaving behind LREE in weatherable secondary minerals, such as synchysite-(Ce) and allanite. Mass balance calculation results also confirm that more HREE are lost from weathered bedrocks than LREE. Therefore, the interaction of groundwater and granitic bedrocks may be favorable to enrich LREE rather than HREE in the regolith. This may explain why most regolith-hosted REE deposits like Zuokeng in South China are of predominant in LREE. This study highlights the role of groundwater in mobilizing, fractionating and enriching REE from the granitic bedrocks to resultant regolith-hosted REE deposits. [ABSTRACT FROM AUTHOR]

New geochemical data of the Iron Oxide-Copper–Gold (IOCG) mineralization and its host rocks in the Dara area, North Eastern Desert of Egypt, are investigated for a better understanding of their petrogenesis. The host rocks are classified into metagabbro-diorite and I-type younger granitoids (monzogranite and alkali feldspar granites). The metagabbro-diorite rocks are volcanic arcs with calc-alkaline affinity and were generated by partial melting of mantle related to the subduction zone. The monzogranite and alkali feldspar granite are metaluminous to weakly peraluminous with calc-alkaline and highly fractionated I-type affinity, respectively. The monzogranite was suggested to be generated from the partial melting of the lower mafic crust, whereas the alkali feldspar granites were from the upper continental crust. IOCG mineralization at the Dara prospect is confined along contacts between the metagabbro-diorite and monzogranite rock types in the form of quartz and quartz-carbonate veins surrounded by alteration zones. The IOCG mineralization is structurally controlled where the quartz and quartz-carbonate veins follow rejuvenation NW–SE compressional Najd fault to E-W and NE-SW extensional fault systems. The hydrothermal mineralization consists of magnetite, hematite, specularite, quartz, calcite, chalcopyrite, minor pyrite, and native gold. Hydrothermal alteration is subdivided into inner sericite-rich and outer chlorite-rich zones. Chemical discrimination using CCPI (chlorite-carbonate-pyrite chemical index), AI (alteration index), and mass balance calculation suggests a redistribution of most elements during alteration without extensive elemental changes except for Eu and Ho. The field, mineralogical, and geochemical features advocated that the mineralization is akin to be related to the Iron Oxide-Cu-Au (IOCG) system that could be linked to the post-collisional tectonic setting of the Arabian-Nubian Shield (ANS). [ABSTRACT FROM AUTHOR]

Gold mineralization in the El-Barramiya region of the Eastern Desert, Egypt, is connected to the post-accretionary stage throughout the Central Eastern Desert. It is represented by quartz, quartz-carbonate veins and disseminations in listvenite rocks. The thrust contact between rock units in El-Barramiya area played an imperative part in gold mineralization where the obduction of ophiolitic rocks over the metasediments and metavolcanics caused shear zones. Mineralization in the study area formed along shear zones and the gold mineralization prefers to precipitate along the transition zone between low-grade regional metamorphic area which is represented by metasediments and high grade which is represented by actinolite schist. The gold mineralization lode of El-Barramiya gold mine area is situated in E–W trending quartz and quartz-carbonate veins along a shear zone located in the intersections between faults trend in NE–SW (Najd fault), NW–SE and thrust faults trend in NEE–SWW in metavolcanic and metasedimentary host rocks. Porphyry granite in the mine area played an important role in hydrothermal alteration process where it represents the source of K, listvenite formed when fluids rich in CO2 and bearing-K permeate and alter the previously altered ultramafic rocks, usually serpentinites of the ophiolitic mélange rocks. The listvenitization process includes silicification and carbonatization metasomatic processes, tectonized serpentinites are altered to listvenite as the carbonatization becomes more intense close to dipping transpressive faults. Geochemical studies of listvenite and mineralized veins helped to determine the ultramafic genesis of listvenite and gold transformed as gold bisulfide. The whole rock geochemical data from El-Barramiya and elsewhere indicate that the transformation of serpentinite into listvenite involves profound metasomatic modification of the bulk-rock geochemistry. The chemical changes during alteration of serpentinite to listvenite are dominated by the addition of CO2, the removal of H2O, and the redistribution of SiO2, MgO and CaO as carbonate minerals and silica replace serpentine. All listvenites at El-Barramiya lode gold deposit are enriched in CaO, Fe2O3 and K2O, but depleted in MgO compared with associated serpentinite that is presumed to represent their protoliths. The chemical changes during alteration of serpentinite to listvenite are dominated by the addition of CO2, the removal of H2O, and the redistribution of SiO2, MgO and CaO as carbonate minerals and silica replace serpentine. Alteration also caused redistribution of trace elements, with some being locally remobilized within the rock, some being added from a fluid phase, and others being leached out of the rock. Petrographic investigation and geochemical studies show different types of alterations (carbonatization and silicification) and mineralization. Mineralizations are represented by gold and sulfides (pyrite, arsenopyrite and smaller quantities of chalcopyrite, sphalerite, galena, tetrahedrite and gersdorffite) found in auriferous quartz veins and disseminated in listvenite. The area exposed to brittle–ductile deformation in addition to different types of structures such as faults and fractures controlling on the formation of mineralization and act as hydrothermal channels ways for fluid flow. Fluid inclusions studies revealed that gold mineralization was formed from heterogeneous trapping of H2O–CO2 fluids at a temperature of 280–340 °C and pressure within the range of 1.5–1.9 kbar, which is consistent with the mesothermal conditions. [ABSTRACT FROM AUTHOR]

The ages of hydrothermal Hg deposits are difficult to constrain because of the lack of suitable minerals for dating. The South China low-temperature metallogenic domain hosts numerous Hg deposits, including the Jianyan Hg deposit that is composed mainly of cinnabar and calcite. There are two stages of calcite in the deposit: syn-ore calcite (Cal-I) and post-ore/barren calcite (Cal-II). Cal-I is mainly euhedral-subhedral and fine-grained, has homogeneous grey luminescence, and is associated with cinnabar. Subhedral-anhedral Cal-II crosscuts Cal-I and is relatively coarse-grained. The syn-ore Cal-I has high U contents (0.1–1.3 ppm) and U/Pb ratios (up to 4.2), and is thus suitable for U-Pb dating. Using a laser ablation-inductively coupled plasma-mass spectrometer equipped with ion counters, we obtained a U-Pb age of 426.3±5.7 Ma (MSWD=1.5) for Cal-I. This age is interpreted to represent the timing of Hg mineralisation at Jianyan and is similar to ages of 440–400 Ma reported for many carbonate-hosted Pb-Zn and Ba-F deposits in South China. Based on the present results in combination with existing geochemical and geochronological data, we infer that these deposits belong to a Paleozoic Hg-Pb-Zn-Ba-F mineralisation system that was controlled by Caledonian tectonism. [ABSTRACT FROM AUTHOR]

To develop simultaneous and in-situ detection techniques towards Cr(VI) and Mn(II), Eu/Tb@CDs with white fluorescence were prepared by a one-step hydrothermal method. With the increase of Cr(VI), all fluorescence channels of Eu/Tb@CDs exhibited obvious quenching, and the detection limit (LOD) was 0.10 μM. In the presence of Mn(II), only the fluorescence from Tb and Eu was quenched, while the fluorescence of CDs was not effected. The LOD for Mn(II) was 0.16 μM. More importantly, in the actual water samples where Cr(VI) and Mn(II) coexist, Eu/Tb@CDs can realize their rapid and simultaneous detection by simple spectral calculation. The selective and competitive experiments have also confirmed that the detection of Cr(VI) and Mn(II) was not interfered by common pollutants in groundwater. It is undeniable that the simultaneous detection of multiple targets by one probe not only greatly improves the detection efficiency, but also has important significance for the field monitoring of water quality parameters. [ABSTRACT FROM AUTHOR]

Khaf Al Laasif is a small (about 100-m long) old mine in the vicinity of Muscat, Oman, with traces of copper and lead. On the contrary to most of the copper mines in Oman developing in ophiolites, Khaf Al Laasif developed in Neoproterozoic metamorphosed dolomite of the Saih Hatat Dome. The copper and lead mineralization was plausibly formed during hydrothermal events that followed major tectonic events in the area. The mine was dug using fire-set mining and that crushing of the mined material was on the spot. The survey of the mine volume has made it possible to estimate the corresponding volume of woody fuel and the minimum forest area necessary for its excavation, which is considerable. Beyond the interest of a site allowing the study of fire-set mining techniques, this paper argues that the main limiting factor to the mine exploitation was the supply of woody fuel, wood or charcoal. It raises questions that could lead to future research on subjects that have been curiously little addressed until now: where did the woody fuel come from and what was the huge paleo-environmental impact of its massive exploitation, at what time does this exploitation go back and in what circuits and socio-economic contexts does it correspond? The main objective of this preliminary study is to reveal the interest of this site and the multidisciplinary issues associated with it. [ABSTRACT FROM AUTHOR]

The origin, evolution, and interplay of brine and hydrocarbon fluid systems play a crucial role in the formation of deep sediment-hosted base metal ore deposits. Here we investigate ratios of halogens, noble gases, stable C and S isotopes, and metal budgets of aqueous brines, which deposited deep-seated and near-surface hydrothermal Zn-Pb mineralization hosted by Zechstein carbonates in the Lower Saxony Basin (North German Basin), by studies of fluid inclusions in sphalerite and quartz. Major and trace element geochemistry and noble gas isotopic signatures of brine inclusions revealed that the ore-forming fluids were highly reactive and experienced prolonged interactions with host rocks in the constricted, over-pressured metal source regions and consequently evolved from near-neutral, oxidized brines towards more reduced, acidic high-salinity brines. Quartz-hosted halite-saturated fluid inclusions with Th <200°C contain Zn and Pb concentrations up to ca. 9400 μg g-1 and 5200 μg g-1, respectively, and indicate the efficiency of metal scavenging processes. The interactions with Westphalian coals and Corg-rich shales influenced the redox state as well as the trace and critical element budget of the sphalerite-hosted fluid inclusions, with enrichment in Ge, Pd, Sb, Tl, Bi, and Ag. The salinities of metalliferous fluids originated primarily from seawater evaporation, however in addition a significant halite-dissolution component is present in the southern part of the Lower Saxony Basin. High concentrations of radiogenic noble gases and potassium in the sphalerite-hosted fluid inclusions are ascribed to strong interactions with the Paleozoic siliciclastic sedimentary pile and crystalline basement rocks. Reflux of the strongly modified, sulfur-poor, Zn-Pb-bearing acidic brines, proceeded via re-activated structurally controlled pathways into sour gas or gas-saturated brine pools in the Zechstein Ca2 carbonate unit. Here, mixing of the ascending metal-rich brines with H2S derived from thermochemical sulfate reduction (TSR), resulted in the deposition of deep-seated Zn-Pb ores in the Lower Saxony Basin. The overall timing of the Zn-Pb ore formation can be constrained to the Upper Cretaceous basin inversion. [ABSTRACT FROM AUTHOR]

The Montecristo district, northern Chile, is one of the few places worldwide where there is a direct relationship between magnetite-(apatite) (MtAp) mineralization and iron oxide-copper–gold (IOCG) mineralization. The MtAp mineralization includes Ti-poor magnetite, fluorapatite, and actinolite and is crosscut and partially replaced by a younger IOCG mineralization that includes a second generation of actinolite and magnetite with quartz, chalcopyrite, pyrite, and molybdenite. The MtAp stage at Montecristo is interpreted as the crystallized iron-rich melts that used the pre-existing structures of the Atacama Fault System as conduits. These rocks later acted as a trap for hydrothermal IOCG mineralization. Geochronology data at Montecristo indicate that the host diorite (U–Pb zircon 153.3 ± 1.8 Ma, 2-sigma), MtAp mineralization (40Ar-39Ar in actinolite, 154 ± 2 Ma and 153 ± 4 Ma, 2-sigma), and the IOCG event (Re-Os on molybdenite, 151.8 ± 0.6 Ma, 2-sigma) are coeval within error and took place in a time span of less than 3.4 Ma. The εHfi and εNdi values of the host diorite are + 8.0 to + 9.8 and + 4.3 to + 5.4, respectively. The whole-rock 87Sr/86Sri values of the IOCG mineralization (0.70425 to 0.70442) are in the lower end of those of the MtAp mineralization (0.70426–0.70629). In contrast, εNdi values for the IOCG mineralization (+ 5.4 and + 5.7) fall between those of the MtAp rocks (+ 6.6 to + 7.2) and the host diorite, which suggests that the IOCG event was related to fluids having a more crustal Nd (εNdi < + 5.7) composition than the MtAp mineralization. This likely reflects the mixing of Nd from the MtAp protolith and a deep magmatic-hydrothermal source, very likely an unexposed intrusion equivalent to the host diorite. Sulfur isotope compositions (δ34S, + 0.3 to + 3.4‰) are consistent with a magmatic source. [ABSTRACT FROM AUTHOR]

A novel magnetic nano-biocomposite (MNBC) was introduced as an adsorbent for a dispersive magnetic solid-phase extraction procedure. The synthesis of the MNBC is based on the co-precipitation of Ni(II) and Fe(III) ions as their hydroxide forms via a simple hydrothermal method, calcination of the obtained Ni–Fe layered double hydroxide, and hybridation of the resultant NiO–NiFe2O4 MNC with chitosan nanoparticles. After prosperous synthesis and characterization of the MNBC, it was applied as an effectual adsorbent for the extraction and pre-concentration of cadmium ions (Cd(II)) from aqueous solutions followed by flame atomic absorption spectrometry detection. The essential factors affecting the extraction recovery were investigated and optimized. According to the method validation, the method's linear dynamic range was from 0.2 to 30 ng mL‒1 with a determination coefficient of 0.9996, and the limit of detection was calculated to be 0.02 ng mL‒1. The precision of the method in terms of intra-day and inter-day relative standard deviations (n = 6) with a concentration of 20 ng mL‒1 Cd(II) were 1.42% and 2.11%, respectively. The developed method's accuracy was confirmed by analysis of a certified reference sample. The developed method was applied for the determination of Cd(II) in various water and industrial wastewater samples. The satisfactory relative recovery values between 97.6 and 103.9% were achieved for the spiked samples, confirming the ignorable matrix effect and successive applicability of the method. [ABSTRACT FROM AUTHOR]

Recent studies have reported the significant role of Au-bearing nanoparticles in the formation of hydrothermal gold deposits. Despite the ever-increasing understanding of the genesis and stability of Au-bearing nanoparticles, it is still unknown how they behave when exposed to hydrothermal fluids. Here, we study the nanostructural evolution of Au–Ag nanoparticles hosted within Co-rich diarsenides and sulfarsenides of a natural hydrothermal deposit. We use high-resolution transmission electron microscopy to provide a singular glimpse of the complete melting sequence of Au–Ag nanoparticles exposed to the hydrothermal fluid during coupled dissolution–precipitation reactions of their host minerals. The interaction of Au–Ag nanoparticles with hydrothermal fluids at temperatures (400–500 ºC) common to most hydrothermal gold deposits may promote melting and generation of Au–Ag nanomelts. This process has important implications in noble metal remobilization and accumulation during the formation of these deposits. [ABSTRACT FROM AUTHOR]

Integrating various tools in targeting mineral deposits increases the chance of adequate detection and characterization of mineralization zones. Selecting a convenient dataset is a key for a precise geological and hydrothermal alteration mapping. Remote sensing and airborne geophysical data have proven their efficiency as tools for reliable mineral exploration. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Advanced land imager (ALI), Landsat 8 (L8), and Sentinel 2 data are widely-used data among various types of remote sensing images in resolving lithological and hydrothermal alteration mapping over the last two decades. ASTER is a well-established satellite in geological remote sensing with detailed Short-wave infrared (SWIR) range compared to visible and near-infrared region (VNIR) that controls iron-associated alteration detection. On contrary, ALI has excellent coverage of the VNIR area (6 bands), but does not possess the potentiality of ASTER for the SWIR and thermal regions. Landsat 8 is widely used and highly recommended for lithological and hydrothermal alteration mapping. The higher spatial (up to 10 m) resolution of Sentinel 2 MSI has preserved its role in producing accurate geological mapping. Notwithstanding the foregoing, implementing the four datasets in a single study is time-consuming. Thus, an important question when commencing an exploration project for hydrothermal alterations-related mineralization (orogenic mineral deposits in the current research) is: which dataset should be adopted to fulfill proper and adequate outputs? Here the four widely recommended datasets (ASTER, ALI, L8, and sentinel 2) have been tested by applying the widely-accepted techniques (false color combinations, band ratios, directed principal component analysis, and constrained energy minimization) for geological and hydrothermal alteration mapping of Gabal El Rukham-Gabal Mueilha district, Egypt. The study area is covered mainly by Neoproterozoic heterogeneous collection of ophiolitic components, island arc assemblage, intruded by enormous granitic rocks. Additionally, airborne magnetic and radiometric data were applied and compared with the remote sensing investigations for deciphering the structural and hydrothermal alteration patterns within the study area. The results demonstrated a different extent from one sensor to another, highlighting their varied efficacy in detecting hydrothermal alterations (mainly hydroxyl-bearing alterations and iron oxides). Moreover, the analysis of airborne magnetic and radiometric data showed hydrothermal alteration zones that are consistent with the detected alteration pattern. The coincidence between high magnetic anomalies, high values of the K/eTh ratio, and the resultant alterations confirm the real alteration anomalies. Over and above that, the remote sensing results and airborne geophysical indications were verified with fieldwork and petrographic investigations, and strongly recommend combining ASTER and Sentinel 2 results in further investigations. Based on the outputs of the current research, we expect better hydrothermal alteration delineation by adopting the current findings as they sharply narrow the zones to be further investigated via costly geophysical and geochemical methods in mineral exploration projects. [ABSTRACT FROM AUTHOR]

Water scarcity is becoming a major issue worldwide due to water pollution and population growth, calling for advanced techniques for water reclamation. For instance, advanced oxidation processes using semiconductor photocatalysts appear promising, yet the light-harvesting capacity of semiconductors must be optimized to ensure complete degradation of contaminants. For this, semiconductors have been modified using electrochemical, sol–gel, hydrothermal, co-precipitation, and microwave-assisted methods. Here, we review electro-fabrication strategies for generating photocatalytic systems for wastewater remediation. We found that the photophysical properties of electrogenerated photocatalysts can be optimized by modulating electrochemical parameters, customizing the electrolyte component, integration of other synthetic routes, innovative technology in the electrochemical setup, and optimization at the final crystallization stages. We focus on anodic dissolution, anodization, metal electrodeposition, current and potential, electrolyte agitation and formulation, additives, electrosynthesis temperature, solvents, crystallization and unconventional electrochemical setup. [ABSTRACT FROM AUTHOR]