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Based on the study of the distribution of intra-platform shoals and the characteristics of dolomite reservoirs in the Middle Permian Qixia Formation in the Gaoshiti-Moxi area of the Sichuan Basin, SW China, the controlling factors of reservoir development were analyzed, and the formation model of "intra-platform shoal thin-layer dolomite reservoir" was established. The Qixia Formation is a regressive cycle from bottom to top, in which the first member (Qi1 Member) develops low-energy open sea microfacies, and the second member (Qi2 Member) evolves into intra-platform shoal and inter-shoal sea with decreases in sea level. The intra-platform shoal is mainly distributed near the top of two secondary shallowing cycles of the Qi2 Member. The most important reservoir rock of the Qixia Formation is thin-layer fractured-vuggy dolomite, followed by vuggy dolomite. The semi-filled saddle dolomite is common in fracture-vug, and intercrystalline pores and residual dissolution pores combined with fractures to form the effective pore-fracture network. Based on the coupling analysis of sedimentary and diagenesis characteristics, the reservoir formation model of "pre-depositional micro-palaeogeomorphology controlling shoal, sedimentary shoal controlling dolomite, penecontemporaneous dolomite benefiting preservation of pores, and late hydrothermal action effectively improving reservoir quality" was systematically established. The "first-order high zone" micro-paleogeomorphology before the deposition of the Qixia Formation controlled the development of large area of intra-platform shoals in Gaoshiti area during the deposition of the Qi2 Member. Shoal facies is the basic condition of early dolomitization, and the distribution range of intra-platform shoal and dolomite reservoir is highly consistent. The grain limestone of shoal facies is transformed by two stages of dolomitization. The penecontemporaneous dolomitization is conducive to the preservation of primary pores and secondary dissolved pores. The burial hydrothermal fluid enters the early dolomite body along the fractures associated with the Emeishan basalt event, makes it recrystallized into medium-coarse crystal dolomite. With the intercrystalline pores and the residual vugs after the hydrothermal dissolution along the fractures, the high-quality intra-platform shoal-type thin-layer dolomite reservoirs are formed. The establishment of this reservoir formation model can provide important theoretical support for the sustainable development of Permian gas reservoirs in the Sichuan Basin. [ABSTRACT FROM AUTHOR]

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Hydrothermal mineral systems are formed by the transport of metals from large source areas through convective fluid flow, subsequent leading to deposition of these metals at specific sites. The fluid pathways are crucial for connecting mineral sources with favorable zones of mineral deposition. However, due to the complexity of fluid flow and limitations in sampling cost, assay cost, and expert experience, inferring fluid pathways poses a significant challenge. In this paper, we leverage the continuous and extensive characteristics of exploration data to identify fluid pathways in hydrothermal deposits, uncovering the hidden patterns from their mineralization footprints and favorable structural features within the data. By modeling the fluid flow as a Markov process, we tailor a hidden Markov model (HMM) to identify fluid pathways using observations of mineralization and structural features. Specifically, we identify the latent geometry of fluid pathways by maximizing their posterior probability as represented by the HMM. We then represent the identified fluid pathways as two quantitative and mappable exploration criteria—trajectory length and pathway flux—which serve as predictor variables in 3D mineral prospectivity mapping. Our method is applied to the Xiadian orogenic gold deposit in the Jiaodong Peninsula, China. The results suggest that the formation of Xiadian deposit is attributed to a series of fluid trajectories originating from two injection points. By using the exploration criteria derived from the identified fluid pathways, we significantly enhance the accuracy and efficacy of mineral prospectivity mapping, demonstrating the proposed HMM as an effective artificial intelligence tool for mineral exploration targeting. [ABSTRACT FROM AUTHOR]

The giant Cretaceous Jiaodong gold province is the world's third largest gold mining district, while the source of the ore-forming fluids and Au S remains controversial. The elemental sulfur is a key carrier for gold and the isotopic composition is an ideal tracer of the sulfur source, which makes it crucial for understanding gold deposit genesis and guiding ore exploration. Here, we show the Au-bearing pyrite in the gold deposits from Jiaodong bears a non-zero Δ33S signature from −0.07 ‰ to 0.31 ‰ showing the mass-independent fractionation (S-MIF). This clearly indicates involvement of Archean atmospheric sulfur during the Cretaceous gold mineralization. The MIF-bearing sulfur was likely remobilized from the Archean supracrustal rocks in the basement of the Jiaodong region via fluid-rock interaction while the hydrothermal ore-forming fluids passed through the crustal-scale fault zones. The Phanerozoic gold deposits from Jiaodong have relatively minor S-MIF signals compared with the Archean orogenic gold deposits due to more material (S) cycling and dilution. This new discovery of S-MIF signal in the Phanerozoic ore deposits implies that the recycling of crustal sulfur may be a more common process and play an important role in forming hydrothermal gold deposits. [ABSTRACT FROM AUTHOR]

Situated in northeastern Hunan Province, the vein-type Pb-Zn orebodies at Taolin are mainly hosted in NE-/NEE-trending faults between Dayunshan-Mufushan pluton and Neoproterozoic metasedimentary rocks of the Lengjiaxi Group. Hydrothermal mineralization can be divided into five stages: (1) coarse-grained quartz stage, (2) quartz-fluorite-base metal stage, (3) quartz-barite-fluorite-base metal stage, (4) pale pink and colorless quartz stage, and (5) fine-grained quartz stage. In this research, fluid inclusions as well as stable (H-O) and noble gas (He-Ar) isotope compositions were performed to uncover the nature, origin, and evolution of the ore-forming fluids, ore precipitation mechanisms, and mineralization process of the Taolin deposit. Four types of fluid inclusions, i.e., liquid-rich two-phase inclusions (LV-type), pure liquid phase inclusions (PL-type), vapor-rich two-phase inclusions (VL-type), and pure vapor phase inclusions (PV-type), were distinguished in sphalerite, quartz, and fluorite. Microthermometric analysis of fluid inclusion assemblages in sphalerite, quartz, and fluorite from different stages indicates that from the Stage 1 to Stage 5, the homogenization temperatures vary between 168 and 211 °C, between 151 and 198 °C, between 131 and 180 °C, between 132 and 164 °C, and between 118 and 138 °C, respectively, whereas the fluid salinities vary from 12.4 to 16.9 wt% NaCl equivalent, from 9.7 to 14.6 wt% NaCl equivalent, from 5.6 to 10.3 wt% NaCl equivalent, from 3.6 to 9.7 wt% NaCl equivalent, and from 0.9 to 3.8 wt% NaCl equivalent, respectively. The H-O isotope data of quartz and the He-Ar isotopic compositions of sulfide crystals suggest that the ore-forming fluids were a mixture of crust-derived magmatic hydrothermal fluid and meteoric water. Fluid mixing and cooling were likely the crucial mechanisms for ore precipitation. [ABSTRACT FROM AUTHOR]

The Jiawula-Chaganbulagen (Jia-Cha) ore field is located in the part of the southern Erguna Block of Northeast China and has significant mineralization potential. It comprises three deposits: The Chaganbulagen hydrothermal vein-type Pb Zn (Ag) deposit in the southeast, the Jiawula hydrothermal vein-type Pb Zn (Ag) deposit in the northwest, and the blind porphyry Mo mineralization in between. Previous geochronological dates, including molybdenite Re Os, zircon U Pb, sulfide Rb Sr, and sericite Ar Ar, indicate that the formation of hydrothermal molybdenite and the Pb Zn mineralization were coeval and that they originated from a porphyry-epithermal metallogenetic system that was related to Early Cretaceous magmatism. However, our comprehensive analysis of fluid inclusions and H-O-He-Ar isotopes reveals dissimilarities in the features and sources of the fluids that form three different deposits. Both the Jiawula deposit and porphyry Mo mineralization have three distinct types of fluid inclusions, which comprise liquid-rich two-phase aqueous inclusions (L-type), vapor-rich two-phase inclusions (V-type), and daughter mineral-bearing three-phase inclusions (S-type). The He Ar (3He/4He = 1.32–1.51 Ra; 40Ar/36Ar = 300 to 324) and H O (δ18O H2O = − 13.4 ‰ to 4.1 ‰; δD = − 155.1 ‰ to −129.9 ‰) isotope analysis results suggest that the trap fluids originated from an H 2 O-NaCl magmatic fluid system, which experienced Mo mineralization with high-temperature transformed into medium-temperature fluids that were primarily of meteoric water in the late-stage (Jiawula Pb Zn (Ag) deposit). The Chaganbulagen Pb Zn (Ag) deposit features L-type and V-type inclusions, along with aqueous‑carbonic inclusions (C-type). The results of Laser Raman analysis reveal that the gas phases of the fluid inclusions present in Chaganbulagen contain three different compositions: H 2 O, CO 2, and CH 4. The H O isotope compositions (δ18O H2O = −18.8 ‰ to −11.6 ‰; δD = −166 ‰ to −131 ‰) and He Ar (3He/4He = 0.034–0.041 Ra; 40Ar/36Ar = 296–298) in quartz of the Chaganbulagen Pb Zn (Ag) deposit indicate that the crustal fluids (MASW) were the main source of the ore-forming fluids, and belonged to a H 2 O-NaCl-CO 2 -CH 4 system, which had low-temperature and low-salinity characteristics. By combining previously published geochronological dates, we proposed a model to explain the difference in the evolution of the fluids. • Our comprehensive analysis of fluid inclusions and H-O-He-Ar isotopes reveals dissimilarities in the features and sources of the fluids that form three different deposits. • We proposed a model to explain the difference in the evolution of the fluids in the one magmatic-hydrothermal event during the Early Cretaceous. • The ore-forming fluids in the Jiawula Pb-Zn (Ag) deposit and Mo mineralization evolved from a magmatic fluids. In contrast, the fluids in the Chaganbulagen Pb-Zn (Ag) deposit is dominated by meteoric water which obtained carbonaceous components from the carbonaceous strata of through water-rock interaction. [ABSTRACT FROM AUTHOR]

With ultra-high thermal significances, the nano-materials present some fundamental applications in many thermal engineering eras, mechanical and chemical engineering and modern technology. For sustainable development of industrial growth of a country, the enhancement in energy production and resources become one of the most fundamental challenges for scientists. This analysis presents the thermal aspects of dust nanoparticles in a dusty nano-material for the interaction of transverse magnetic field come across an expanding surface. The conjunction of Maxwell model thermal conductivity influences the characteristic of thermal properties that is helpful to enrich the heat transport phenomena. A mathematical model is prepared by considering metal nano-material (copper and silver) in association with the conventional fluid water. The numerical treatment is deployed for the solution of the complex nonlinear problem characterized by dust phase material and fluid transformed governing equations. The transport of heat energy is affected by the transient behavior of the volume fraction, dust particle number density in conjunction with magnetic field. However, the key features of the outcomes for the characterizing parameters are lubricated through graphs and simulated numerical values for the rate coefficients are presented in table that leads to the validation work with the earlier investigation. An increment in heat transfer rate is noted with suspension of copper nanoparticles in the dusty fluid while heat transfer reduces in case of silver nanoparticles. The nanoparticles temperature enhanced with interaction parameter and specific heat ratio. The current analysis has a greater impact in bio-medical since i.e. the blood flow within the artery as well as several industrial and engineering applications. All these aspects depend upon the nanoparticles particle size therefore the dust and nanoparticles proposed here are spherical. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm called Grasshopper optimization for solving short-term hydrothermal scheduling problem. The objective of this problem is to reduce the generation cost by optimizing the output of power generation of different thermal and hydro plants for a certain time interval. A non-linear relationship between hydropower generation, net head, and rate of water discharge is considered here. A complex piecewise output limit and head-sensitive conversion of water-to-power is applied here. To investigate the performance of this new technique, three test systems have been considered. The results obtained by this Grasshopper optimization algorithm are compared with those of other wellknown soft computing techniques. The effcacy of this proposed technique was verified after comparison with other similar soft techniques. [ABSTRACT FROM AUTHOR]

This work deals with the unique TiO2/Cu2O nanocomposite was synthesised by a hydrothermal precipitation way and high photocatalytic degradation of target organic toxin over the photocatalytic coordination. The structure, morphology, composition, optical and photocatalytic belongings of the as-prepared nanomaterials (NMs) were analytically considered in aspect. In 80 min of exposure time, closely 94.5% decolourization proficiency and the removal rate of MB dye were attained by TiO2/Cu2O photocatalyst, which is abundantly greater than that of bare Cu2O (61.5%) and TiO2 (40%) photocatalysts (PCs) individually. The photodegradation kinetics of TiO2/Cu2O nanocomposite on MB dye was analytically discovered and the apparent rate kinetic was 5.1 folds grander related than pristine TiO2. The TiO2/Cu2O photocatalyst also maintains worthy recycling steadiness up to four successive photodegradation cycles. Moreover, these novel TiO2/Cu2O nanocomposite owns great prospective for visible-light-driven organic impurities devastation from the wastewater. [ABSTRACT FROM AUTHOR]

Mesoporous zinc-manganese oxide decorated carbon nanocomposites, as promising low-cost candidates for chromate(VI) sorption, were developed via a one-pot facile route based on battery wastes. The improved-based carbon composite with (ZnMn 2 O 4 +MnO(OH)/Mn 2 O 3 ·H 2 O/C (I-C)) was produced by in-situ hydrothermal growth. Furthermore, the treated composite of carbon with adding ZnSO 4 solution (ZnMn 2 O 4 /C (T-C)). Nanocomposites were characterized comprehensively using FTIR, XRD, HR-TEM, XPS, EDX, and BET analyses. The T-C nanocomposite showed a significant enhancement of chromate sorption by 1.5 fold in comparison with I-C in terms of maximum capacity and equilibrium time. Langmuir and pseudo-second-order fit the experimental data well. The sorption process is spontaneous, endothermic, and governed by entropic. The interaction mode was elucidated via FTIR, XRD, and XPS data, unveiling a synergistic ion-pair sorption and redox mechanism. Elution and sorbent regeneration were successfully achieved using HCl (0.2 M) with high durability over seven cycles. Finally, both nanocomposites, especially T-C, demonstrated exceptional efficiency and selectivity in removing high levels of Cr(VI) from wastewater from tannery industries. [Display omitted] • Two mesoporous ZnMn 2 O 4 /carbon nanocomposites were hydrothermally synthesized from zinc-carbon batteries wastes. • The pure spinal structure of ZnMn 2 O 4 /carbon nanocomposite improves the efficiency by ⁓1.50 time. • The Langmuir capacities are 3.64 and 5.50 mmol/g for I-C and T-C, respectively at pH 0 2.5. • FTIR, XRD and XPS data reveal a synergistic ion-pair sorption and redox mechanism. • Outstanding selectivity for Cr(VI) sorption from industry tanneries effluents. [ABSTRACT FROM AUTHOR]

• Rare earths are main source of revenue among coproducts of most secondary sources. • Different sources within each category shows large variability in contained value. • Industrial waste revenues are driven by scandium, electronic waste by neodymium. • Contained rare earth value increases as power law of total rare earth oxide content. Expanding use of rare earth elements (REEs) necessitates characterizing deposits. Challenges include variable REE concentrations (e.g., coal ash ranges from 267 to 843 ppm) and price volatility. For a range of sources, we estimate distributions in the REE value per tonne of material, by collecting multiple data points for each type and using mean-reversion price forecasting. The study covers primary ores (e.g., bastnaesite), industrial wastes (e.g., red mud) and consumer wastes (e.g., NiMH batteries). Electronic wastes have highest value, driven by neodymium, industrial waste value is driven by scandium. Variability exists within resource types, e.g., the value of Australian monazite > Bayan Obo bastnaesite > Malaysian monazite. Using a power-law relationship, the total REE value of a sources correlates well with its ore grade. These results inform investment decisions to develop primary and secondary sources by clarifying potential variability and providing a useful rule of thumb to estimate revenues. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hydrothermal leaching of LiMn 0.5 Co 0.2 Ni 0.3 O 2 is proposed using carbonate ester as additive. • 98.58 % lithium is leached with nearly 100 % selectivity. • Above 99.8 % lithium product purity is achieved. • Lithium extraction for LiMn 2 O 4 , LiCoO 2 , and various NCM cathode materials are feasible. • Detailed leaching mechanism is explored. Recycling lithium from lithium-ion batteries (LIBs) and reducing electrolyte pollution are challenges for the sustainable development of the LIBs industry. Herein, we report a novel strategy for the selective recovery of lithium from spent LiMn 0.5 Co 0.2 Ni 0.3 O 2 (NCM523) cathode materials via hydrothermal leaching using a carbonate ester derived from an electrolyte as the leaching agent. Lithium was leached via either the common linear or cyclic carbonate ester used in the electrolytes, and 98.58 % of the lithium was recovered with nearly 100 % selectivity using the carbonate ester mixture. Meanwhile, a lithium recovery purity above 99.8 % was achieved, which was attributed to the absence of the leaching of other metals. The lithium extraction using the actual recovered carbonate ester or different types of LIBs materials (LiMn 2 O 4 , LiCoO 2 , and various NCM cathode materials) is feasible. This work provides new inspiration for recycling lithium from spent LIBs in an eco-friendly and sustainable manner. [Display omitted] [ABSTRACT FROM AUTHOR]

Lead isotopes are useful in determining the source of metals in environment, and studies on lead isotopic characteristics of mineral deposits have provided important insights for economic geologists, archaeologists and environmental scientists over the past 50 years. This study reports new Pb isotope and trace element data of sulfide minerals from 25 mineral deposits in Japan in order to partly update the data set reported in the 1980s, which have long been used for provenance studies. The analytical precision of the Pb isotope ratios, measured by multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) in this study, is an order of magnitude higher than the previous data set, allowing regional- and deposit-level discrimination of isotopic signatures. The Pb isotope ratios of vein-type or intrusion-centered Japanese deposits from this study (206Pb/204Pb = 18.151–18.545, 207Pb/204Pb = 15.552–15.642, 208Pb/204Pb = 38.389–38.918) are mostly within the range of data from Japanese deposits of the same type measured in previous studies but tend to have slightly lower 207Pb/204Pb and 208Pb/204Pb ratios. This is likely be due to the differences in analytical instrumentation and isotopic variations within the deposit, which should carefully be considered in future regional-scale provenance studies. Data from the Sai, Ohizumi, Budo and Shiraita deposits in Northeast Japan as well as the Kishu and Tokoo deposits in Southwest Japan indicate a two-component mixing presumably involving magma and meteoric fluid. The isotopic variation within each of these deposit is much smaller compared to previously reported variations within volcanogenic massive sulfide deposits in Japan, indicating a relatively uniform metal source with only a small contribution from basement rocks. In contrast, Daira and Ani deposits in Northeast Japan have highly variable isotopic characteristics similar to volcanic rocks with lower crustal assimilation, indicating an additional input of material from the lower crust. [ABSTRACT FROM AUTHOR]

The Khan-Khatun Zn Pb deposit is located in the southeast margin of the Tabas Block of the Central Iranian Microcontinent. The stratabound Zn Pb mineralization is of epigenetic origin and hosted by the Late Cretaceous limestones. The ore deposition occurred in structural open spaces and much less as a disseminated replacement in carbonate rocks. The deposit consists of sulfide and non-sulfide base metal ore types. Sulfide ores include sphalerite, galena, and minor amounts of pyrite and chalcopyrite. Three paragenetic stages are recognized: pre-, hydrothermal, and supergene mineralization. Fine-grained pyrite and chalcopyrite (0.02 to 0.15 mm) precipitated during the early stages of hydrothermal mineralization. Galena formed with or sometimes after sphalerite. The δ34S values of sphalerite and galena range from +10.4 ‰ to +13.7 ‰ and + 10.2 ‰ to +14.1 ‰, respectively, and are consistent with thermochemical sulfate reduction (TSR) of the Jurassic evaporites. Willemite is an abundant non-sulfide mineral characterized by red-brown to white colors. The red-brown willemite formed during the late stages of the hydrothermal mineralization. The δ18O values of red-brown and white-colored willemite vary from +14.3 to +16.1 ‰ and − 9.62 to −8.1 ‰, respectively. Differences in δ18O values between red-brown willemite and white-colored willemite are probably the result of hydrothermal and supergene processes. Homogenization temperatures of primary fluid inclusions in calcite coexisting with sulfide ores and red-brown willemite range from 110 to 210 °C and 112 to 177 °C, respectively. The salinities of aqueous fluid inclusions of calcite and red-brown willemite vary from 11.1 to 21.26 wt% NaCl equiv. and 10.61 to 16.15 wt% NaCl equiv., respectively. Microthermometric measurements, isotopic analyses, geochemical, mineralogical, and textural evidence indicate that the mineralization process at the Khan-Khatun Zn Pb deposit is consistent with Mississippi Valley-type (MVT) deposits. [ABSTRACT FROM AUTHOR]

The newly discovered Zhuanghuhe Au–Sb occurrence is located 20 km north of the famous Duobaoshan Cu–Mo deposit, it is the first gold–antimony deposit discovered in the Duobaoshan orefield. The hydrothermal quartz vein-type orebodies occur in the Middle Ordovician Duobaoshan Formation and are controlled by NNW and ENE compressional faults. Four mineralization stages are identified: stage I quartz + pyrite + arsenopyrite, stage II quartz + polymetallic sulfides, stage III quartz + stibnite, and stage IV quartz + calcite. Fluid inclusions (FIs) in quartz and calcite veins include six types: types I (two-phase aqueous), IIa (aqueous–carbonic; the volume of the carbon phase <50 %), IIb (aqueous–carbonic; the volume of the carbon phase >50 %, with more CO 2 than CH 4), IIc (aqueous–carbonic; the volume of the carbon phase >50 %, with more CH 4 than CO 2), IIIa (carbonic, with more CO 2 than CH 4) and IIIb (carbonic, with more CH 4 than CO 2). FIs of stage I are types I, IIa, IIb and IIIa, with homogenization temperatures of 279–311 °C and salinities of 4.87–11.84 wt%, indicating a medium-temperature low-salinity immiscible NaCl–H 2 O–CO 2 fluid system. Stage II contains all FI types with final homogenization temperatures of 233–288 °C and salinities of 4.94–8.67 wt%, indicating a medium- to low-temperature low-salinity NaCl–H 2 O–CO 2 –CH 4 system. FIs of stage III contain types I and IIa with homogenization temperatures of 193–240 °C and salinities of 3.85–6.63 wt%, belong to a low-temperature low-salinity NaCl–H 2 O–CO 2 ± CH 4 system. FIs of stage IV contain only type I with homogenization temperatures of 158–212 °C and salinities of 2.56–4.01 wt%, indicating a NaCl–H 2 O system. The H–O–C isotope data show that the NaCl–H 2 O–CO 2 fluids of stage I (δD = −98 to −105.7 ‰, δO H 2 O = 5.7 to 6.9 ‰, δ13C CO 2 = −11.9 to −11.1 ‰) were derived from a magmatic system, the fluids of stage II (δD = −85.7 ‰, δO H 2 O = 2.8 ‰, δ13C CO 2 = −14.2 ‰, δ13C CH 4 = −32.5 to −31.9 ‰) were characterized by the addition of CH 4, which might have come from the reaction between the original ore-forming fluids and carbonaceous slate of the Duobaoshan Formation. The fluids in stage III (δD = −90.2 to −89.6 ‰, δO H 2 O = −9.1 to −6.1 ‰) and stage IV (δD = −110.6 to −96.3 ‰, δO H 2 O = −13.0 to −12.6 ‰) were characterized by mixing of meteoric water. According to the geology, fluid inclusion and H-O-C stable isotope evidences, the initial magma-derived NaCl-H 2 O-CO 2 fluids were immiscible in stage I and then the process of mixing with CH 4 -bearing fluids in stage II, resulting in the gold precipitation; the precipitation of antimony was mainly related to the temperature drop and the mixing of meteoric water in stage III. [Display omitted] • The Zhuanghuhe Au–Sb mineralization belongs to hydrothermal quartz vein-type. • The initial NaCl-H 2 O-CO 2 ore fluids were primarily derived from a magmatic system. • The organic CH 4 was from the reaction between initial fluids and carbonaceous slate. • Ore-forming fluid immiscibility and mixing controlled the ore precipitation. [ABSTRACT FROM AUTHOR]

The Zijinshan district, Fujian Province, southeastern China, is a globally renowned Cu Au orefield and hosts a wide variety of ore deposits within the Zijinshan granite complex and surrounding volcano-sedimentary rocks. We performed Fe S isotope analysis on pyrite separates from the Zijinshan high-sulfidation epithermal deposit, Yueyang intermediate-sulfidation epithermal deposit, Wuziqilong transition-type (from high-sulfidation epithermal to porphyry) deposit, and Jintonghu porphyry Cu Mo deposit, aiming to understand the formation process of Fe-sulfides and the evolution of ore-forming fluids in different deposits. Pyrites from the Jintonghu porphyry Cu Mo deposit show variations in δ56Fe and δ34S from −0.15 ‰ to 0. 45 ‰, and from 1.81 ‰ to 2.70 ‰, respectively. In contrast, pyrites from epithermal-type deposits (i.e., Zijinshan, Yueyang, and Wuziqilong) show a negatively shifted Fe isotopic composition from −1.74 ‰ to 0.45 ‰. The combination of Fe isotopic data from the Jintonghu porphyry Cu Mo deposit with published minerals-fluid fractionation factors and the use of a Rayleigh fractionation model allowed us to determine the δ56Fe range of regional ore-forming fluids (−1.00 ‰ to −0.40 ‰), which is consistent with the previous "light fluid" hypothesis, suggesting that pyrite of porphyry Cu Mo deposits has isotopic compositions reflecting the isotopic value of the hydrothermal fluids. For the epithermal deposits, pyrite Fe isotopic composition is the result of a complex interaction of Rayleigh fractionation, rapid precipitation and kinetic fractionation, and δ56Fe values of the initial fluids is difficult to estimate. Integrating the Fe and S isotope data for pyrite of different genesis, we found that porphyry Cu Mo deposits (δ56Fe: −0.9 ‰ to 0.46 ‰; δ34S: −4.06 ‰ to 3.9 ‰) can be distinguished from a non-magmatic/low-temperature region, while the transitional area of which may be a porphyry-related hydrothermal deposit (i.e., epithermal deposit). In general, we suggest that the Fe and S isotopic signatures of pyrite can effectively distinguish porphyry-type deposits from their associated hydrothermal deposits. [ABSTRACT FROM AUTHOR]

The Inlice high sulfidation epithermal gold deposit with 262,300 oz of gold ore is located in the Erenlerdağ-Alacadağ Volcanic Complex (EAVC) at the northern part of central Taurides. The volcanic succession of the study area is stratigraphically represented by andesite, block and ash flow, basaltic andesite lava flow and andesite lava flow. The deposit consists of seven neighboring mineralized veins termed Ana East, Ana West, West, Discovery, Güllü, Merkez and North Zone and is associated with an andesite (ca 8–9 Ma). Hydrothermal alteration from the innermost to the outermost parts of the deposit includes silicification, advanced argillic, intermediate argillic and propylitic. At the surface, quartz veins related to silicification are exposed as linear topographic relief trending mainly northwest-southeast and secondarily northeast-southwest and east-west. Deep drill core samples, including magnetite, quartz, biotite and anhydrite, imply the presence of potassic alteration in depth (50 to 970 m) possibly related to a porphyry Cu system. Ore assemblages are described as hypogene and supergene. The hypogene ore mainly includes pyrite (Py-I and Py-II) and enargite, and to a lesser extent chalcopyrite, sphalerite and marcasite. The supergene ore incorporates hematite and goethite, and minor covellite, chalcocite, malachite and native copper. Hypogene gold precipitation is associated with the mineral association of Py-II, chalcopyrite and enargite, while enargite mineral is a major host for gold (up to 600 ppm). Supergene oxidation resulted in the development of a secondary enrichment zone for gold (up to 14 g/t) extending to a depth of about 45 m. Microthermometric measurements show that the silicification associated with the mineralization was formed at homogenization temperatures ranging between 147 and 360 °C and salinities up to 6.5 wt% NaCl. This suggests that the fluid mixing and/or fluid dilution processes were important factors controlling the precipitation of gold. δ34S isotope compositions are between −0.9 and − 9 ‰, and further indicate a significant involvement of magmatic components into the hydrothermal fluids. Thus, it is concluded that at Inlice the hydrothermal fluids responsible for the alteration and mineralization processes were derived by relatively dilute fluids formed by the mixing of magmatic fluids with meteoric waters. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of the concentrations of four pretreatment complexing reagents, namely ascorbic acid (AS), citric acid (CA), N, N-bis (carboxymethyl) glutamic acid (GLDA), and ethylenediaminetetraacetic acid (EDTA), on the phosphorus contents and forms in hydrothermally carbonized sludge products. The results showed that among the four complexing reagents, EDTA had the greatest effect on the phosphorus transfer from the solid phase to the liquid phase during the hydrothermal process of the sludge, followed, respectively, by GLDA, CA, and AS. The phosphorus proportion of the liquid phase was 63.96% under hydrothermal process temperature, reaction time, and EDTA concentration of 160 °C, 60 min, and 0.2 mol/L, respectively. The results showed formations of EDTA complexes with Ca, Fe, and Al in the sludge, releasing phosphorus bound to the metal ions into the liquid phase. The highest total phosphorus concentration in the liquid phase was 2533.31 mg/L following the increase in the hydrothermal process temperature from 100 to 160 °C. However, the Fe and Al-EDTA complexes were thermally decomposed after continuously increasing the hydrothermal process temperature to 240 °C, resulting in a readsorption of phosphorus to the solid phase with Fe, Al, and other metals and, consequently, decreasing the phosphorus content to 880.93 mg/L in the liquid phase. The results of this study provide a scientific basis for regulating phosphorus distribution in the solid and liquid phases of hydrothermally carbonized sludge products and effectively recovering phosphorus in the liquid phase. [Display omitted] • The complexing reagents regulated P distribution during the hydrothermal process. • At 100-160 °C, EDTA binds to the metal releasing P into the liquid phase. • The P contents in the liquid phase is considerably reduced at 160-240 °C. [ABSTRACT FROM AUTHOR]

The structure of the Romanian Western Black Sea shelf has been studied for the last 50 years. This paper aims to give a new interpretation, highlight a new vision regarding the lower crust architecture by combining the known local data with new measurements. In 2005, a new set of gravimetric data was collected by the Romanian National Institute of Marine Geology and Geo-ecology (GeoEcoMar), in the project Marine Geohazard, financed by the EU, which summed up to thousands of gravimetric profiles on the Romanian and Bulgarian offshore. By combining the new data with the known geological setting, a new vision emerged regarding the understanding of the complex structural dynamics of the deep shelf area and the geomorphology of the deep geological structure. For this investigation, a set of 3 profiles have been constructed as a starting point for the geological structure. In the process of inserting data, we had to take into consideration all the implicit information available from the local wells that are considered a secure source of upper-structure information. Once the model obtained, the image showed different areas where the Western Black Sea back-arc opening of the basin showed its marks, by presenting an unexpectedly complex architecture, considering all the constraints and local limitations. [ABSTRACT FROM AUTHOR]

The Copper Cliff porphyry copper prospect, located 48 km east-southeast from Missoula, Montana, presents two distinct phyllic alteration events: an early green-colored expression, locally texturally destructive and associated with specular hematite and hypogene copper mineralization, and a later white variety generally structurally controlled and associated with pyrite. Variations in the mineral chemistry of white micas were evaluated by short-wave infrared spectroscopy, electron microprobe analysis, and laser ablation-inductively coupled plasmamass spectrometry (LA-ICP-MS). The analytical results allow the identification of a systematic compositional variation of the white micas, possibly controlled by redox changes in the system. The early green phyllic expression consists of Fe-bearing white micas characterized by longer Al-OI I absorption wavelength (2,206-2,210 nm) and formed by oxidized magmatie fluids, whereas the late white phyllic phase contains white micas enriched in V and Sc with shorter Al-OH absorption wavelengths (2,197-2,206 nm) formed under less oxidizing conditions. Based on LA-ICP-MS trace element analyses of white micas, Cu concentrations decrease exponentially with distance from the porphyiy center, in contrast to Zn, which tends to increase. The application of the Cu/Zn ratio of white micas in a manner analogous to the chlorite proximitor equation of Wilkinson et al. (2015) allows the estimation to the center of the hydrothermal system within a radial distance of approximately 710 m in samples of the early green phyllic alteration phase and within approximately 1,300 m in samples of the late white phyllic alteration style. Therefore, the Cu/Zn ratio in white micas at Copper Cliff deposit may provide a useful tool for targeting the hydrothermal center. [ABSTRACT FROM AUTHOR]

Porphyry Cu deposits form in the shallow crustal parts of arc magmatic systems, which root in the mantle wedge, evolve in lower crustal MASH (melting, assimilation, storage, homogenization) zones and lower to midcrustal hot zones, and accumulate in mid- to upper crustal batholiths at depths of 5 to 10 km. A small proportion of the magma and most of the volatile load rises toward the surface due to buoyancy, and may erupt as volcanic or fumarolic emissions. Low levels of volcanism and fumarolic activity, as well as subsurface hydrothermal flow and alteration, are normal and semicontinuous features of active arc magmatic systems, which may operate for millions of years. Porphyry Cu deposits, on the other hand, form rarely (typically < 1 per batholith) and rapidly (<100,000 years) in the subsurface (2-5 km depth), where hydrous volatiles exsolved from the underlying batholith are channeled into structurally controlled cupola zones and cool before reaching the surface. The explosively brecciated character of early mineralization stages (breccia pipes and stockworks) suggests that the initiation of fluid flow maybe essentially instantaneous and catastrophic, with the longer total duration of hydrothermal activity reflecting slower kinetically controlled fluid exsolution processes, or draining of deeper parts of the system. These fluids generate intense subsurface hydrothermal alteration, and may precipitate economic concentrations of Cu-sulfide minerals in potassic alteration zones as they cool between -400° and 300°C. The suddenness and infrequency of these ore-forming hydrothermal events suggest that they are triggered by an external process acting on otherwise normally evolving magmatic systems. Sudden depressurization or agitation of a large, primed, volatile-saturated or supersaturated mid-upper crustal magma chamber could lead to rapid and voluminous volatile exsolution and fluid discharge. This sudden volatile flux could result in either a large explosive volcanic eruption if the surface is breached, or a large magmatic-hydrothermal system that could form a porphyry Cu deposit if fluid flow is restricted to the subsurface. Candidates for triggers of these destabilizing events are catastrophic mass wasting such as volcanic edifice collapse, or mega-earthquakes, the latter possibly causing the former. The frequency of such catastrophic events occurring in proximity to active arc batholiths may approximate the recurrence rate of formation of large porphyry Cu deposits. [ABSTRACT FROM AUTHOR]

Precisional analyses of the abundances of La, Ce, and major elements in thermal waters and rocks of the Uzon-Geyzernaya volcanotectonic depression, supplemented by published data on a number of modern high-temperature hydrothermal systems of Kamchatka and two other areas of the world, allowed defining genetically important patterns of rare-earth elements (REE) distribution. The La and Ce abundances positively correlate with silica contents both in fresh igneous rocks of the study areas and in the products formed by hydrothermal processes. All studied hydrothermal clays are enriched in La and Ce. The general enrichment trend is similar to the pattern of positive correlation between the La and Ce abundances. Geothermal waters display a strong relationship between REE enrichment and pH. Enhanced REE enrichment trend is observed in thermal waters with abundant SO 4 2 − and K. The REE versus Cl and B diagrams show two individual fields reflecting the level of acidity-alkalinity of thermal waters. These data demonstrate that La and Ce concentrations in the products of modern hydrothermal systems (in fluids and secondary mineral phases) are governed by wallrock composition, anionic water composition, and pH/Eh-dependent adsorption processes. [ABSTRACT FROM AUTHOR]

The hierarchical porous 2MgO·B 2 O 3 ·H 2 O (MBO) microsphere has been prepared by a template-free hydrothermal method, which was characterized by XRD, FT-IR, TG, SEM and TEM. The microsphere nanostructure is assembled by nanobelts array with the thickness of 10 nm and width of 10–30 nm. The possible growth mechanism of the 3D hierarchical MBO nanostructure is also proposed. It has been demonstrated that the as-prepared MBO nanostructure has a porous hierarchical structure with a high specific surface area of 93.64 m 2 /g measured by N 2 adsorption−desorption. It exhibits excellent adsorption performance with maximum adsorption capacity of 183.15 mg/g for Congo red (CR), as well as good recyclability. Moreover, the adsorption process of CR on hierarchical porous MBO was systematically investigated, which was well fitted with the pseudo-second-order rate equation and Langmuir adsorption model. It needs to indicate that the as-prepared hierarchical porous MBO microsphere can be considered as a promising candidate for wastewater treatment. [ABSTRACT FROM AUTHOR]

Fractures and vugs were used as the primary dolomite reservoir space in the study area, which improved the reservoir’s physical properties and influenced the distribution pattern of oil and water that were developed in the Upper Tenger Formation, Lower Cretaceous, Baiyinchagan sag, Erlian Basin. Based on the core observation data, thin slice analysis, and image logging, the cave-fractured reservoir was primarily developed in the actic region near the side of a depositional fault. Tectonic and diagenetic fractures were the primary types of fractures. High-angle tectonic fractures in the closure and open status were developed well in dolomitic mudstone, while a low-angle fracture and reticulate fractures were developed in the tectonic-hydrothermal hybrid process and were filled with hydrothermal minerals. The reservoir was located in low-lying land; therefore, detrital grain pressolution fractures were formed by burial diagenesis. Intergranular and intrangranular dissolved pores, which were formed by hydrothermal activity, were developed primarily in the highly dolomite lithology. According to the diagenesis temperature of dolomite from a carbon-oxygen isotope analysis, multiple hydrothermal fluid injection events occurred, and dolomitization ensued before massive hydrocarbon migration. The dissolution of organic acids formed by hydrocarbon charges after dolomitization and inorganic acid produced by burial di agenesis for soluble minerals effectively promoted the reservoir properties. Strong heterogeneity due to lithology and fracture-vug systems led to intricate oil-water relationships. Four statuses occurred, including cave-fracture oil, isolated oil, stored oil, isolated water, and stored water. The oil-water distribution patterns were established based on the core observation. [ABSTRACT FROM AUTHOR]

There is increasing interest in mining minerals on the seabed, including seafloor massive sulfide deposits that form at hydrothermal vents. The International Seabed Authority is currently drafting a Mining Code, including environmental regulations, for polymetallic sulfides and other mineral exploitation on the seabed in the area beyond national jurisdictions. This paper summarizes 1) the ecological vulnerability of active vent ecosystems and aspects of this vulnerability that remain subject to conjecture, 2) evidence for limited mineral resource opportunity at active vents, 3) non-extractive values of active vent ecosystems, 4) precedents and international obligations for protection of hydrothermal vents, and 5) obligations of the International Seabed Authority under the UN Convention on the Law of the Sea for protection of the marine environment from the impacts of mining. Heterogeneity of active vent ecosystems makes it extremely challenging to identify “representative” systems for any regional, area-based management approach to conservation. Protection of active vent ecosystems from mining impacts (direct and indirect) would set aside only a small fraction of the international seabed and its mineral resources, would contribute to international obligations for marine conservation, would have non-extractive benefits, and would be a precautionary approach. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a promising solution to cope with the large amount of municipal solid waste (MSW) produced in densely populated metropolitan areas of developing countries. But technical and logistical limitations typically necessitate optimal plant locations and a strong supply chain for MSW-based HTC plants to be economically attractive. To that end, a novel linear programming (LP)-based spatial optimization model has been developed that takes multiple critical constraints (biomass availability, hydrochar yield, market demand, costs of transporting and handling biomass and hydrochar, and land cost) into account to maximize the net profit of HTC plants. Dhaka, being a mega city, is burdened with the issue regarding disposal of large quantity of MSW. A case study was conducted based on the MSW management system of Dhaka North City Corporation (DNCC) for two schemes, a single (79.26 MW thermal) plant and a double (39.63 MW thermal) plant, in Dhaka city and its surrounding area. The model showed that the single plant scheme generated a higher profit (~18.5 million USD) than the double plant scheme (~17.7 million USD). Locations within Dhaka city near the secondary transfer stations were found to be favorable for plant establishment in both schemes. Further analysis revealed that plants' net profit is highly dependent on their optimal locations, with total transportation cost being the most significant location-sensitive element. Standardized coefficients suggest that for a single plant scheme, total transportation cost will always have a more dominant effect than land cost. This model will be able to guide the policy makers to take necessary steps for proper management of ever-growing city waste by setting up HTC facilities at optimal locations. • MSW generation poses tremendous handling issues in developing mega cities. • A solution for handling MSW with hydrothermal carbonization (HTC) was assessed. • A spatial model was developed to handle large scale MSW generation using HTC. • Real data from a developing mega city, Dhaka, was used as input in the model. [ABSTRACT FROM AUTHOR]

Remote sensing is a strategic key tool for mineral exploration, due to its capacity of detecting hydrothermal alteration minerals or alteration mineral zones associated with different types of mineralization systems. A case study of an epithermal system located in southern Peru is presented, aimed at the characterization of mineral assemblies for discriminating potential high sulfidation epithermal targets, using hyperspectral imagery integrated with petrography, XRD and magnetic data. HyMap images were processed using the Mixture Tuned Matched Filtering (MTMF) technique for producing alteration map in the Chapi Chiara epithermal gold prospect. Extensive areas marked by advanced argillic alteration (alunite-kaolinite-dickite ± topaz) were mapped in detail, as well as limited argillic (illite-smectite) and propylitic (chlorite spectral domain) alteration. The magmatic-hydrothermal processes responsible for the formation of hypogene minerals were also related to the destruction of ferrimagnetic minerals (e.g., magnetite) of host rocks such as andesite, and the remobilization/formation of paramagnetic Fe-Ti oxides (e.g., rutile, anatase). The large alteration zones of advanced argillic alteration are controlled by structures related to a regional NW-SE trend, and also by local NE-SW and ENE-WSW ones. [ABSTRACT FROM AUTHOR]

This study introduced a different procedure to implement matched filtering algorithm (MF) on the ASTER images to obtain the distribution map of alteration minerals in the northwestern part of the Kerman Cenozoic Magmatic Arc (KCMA). This region contains many areas with porphyry copper mineralization such as Meiduk, Abdar, Kader, Godekolvari, Iju, Serenu, Chahfiroozeh and Parkam. Also argillization, sericitization and propylitization are the most common types of hydrothermal alteration in the area. Matched filtering results were provided for alteration minerals with a matched filtering score, called MF image. To identify the pixels which contain only one material (endmember), an appropriate threshold value should be used to the MF image. The chosen threshold classifies a MF image into background and target pixels. This article argues that the current thresholding process (the choice of a threshold) shows misclassification for MF image. To address the issue, this paper introduced the directed matched filtering (DMF) algorithm in which a spectral signature-based filter (SSF) was used instead of the thresholding process. SSF is a user-defined rule package which contains numeral descriptions about the spectral reflectance of alteration minerals. On the other hand, the spectral bands are defined by an upper and lower limit in SSF filter for each alteration minerals. SSF was developed for chlorite, kaolinite, alunite, and muscovite minerals to map alteration zones. The validation proved that, at first: selecting a contiguous range of MF values could not identify desirable results, second: unexpectedly, considerable frequency of pure pixels was observed in the MF scores less than threshold value. Also, the comparison between DMF results and field studies showed an accuracy of 88.51%. [ABSTRACT FROM AUTHOR]

The Baiyinnuo'er skarn deposit is one of the largest Zn-Pb deposits in northeastern China, with 32.74 million metric tons (Mt) resources averaging 5.44% Zn, 2.02% Pb, and 31.36 g/t Ag. The deposit formed in three stages: the preore stage (prograde skarn minerals with minor magnetite), the synore stage (sulfides and retrograde skarn minerals including calcite and minor quartz), and the postore stage (late veins composed of calcite, quartz, fluorite, and chlorite; cutting the above mineral assemblages). In this study we analyzed the composition of single fluid inclusions using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to (1) determine the composition of the fluids and the evolution through the stages, (2) infer the fluid and metal sources, and (3) explore the metal deposition mechanisms. The preore fluids trapped in pyroxene have higher homogenization temperatures (432°-504°C), higher salinity (36.5-46.1 wt % NaCl equiv), and higher concentrations of Zn (~0.9 wt %), Pb (~1.4 wt %), and other elements (e.g., Na, K, Li, As, Rb, Sr, Cs, Ba, Cl, and Br) than synore mineralizing fluids (<370°C, <10 wt % NaCl equiv, ~450 ppm Zn, and ~290 ppm Pb). The postore fluids show lower temperatures (<250°C) and a rather dilute composition (<4 wt % NaCl equiv, ~33 ppm Zn, and ~24 ppm Pb). Geochemically, the fluids of all paragenetic stages in Baiyinnuo'er have magmatic signatures based on the element mass ratios, including elevated K/Na, Zn/Na, and Rb/Na ratios, lower Ca/K ratios, and combined Cl/Br-Na/K ratios, which are distinctively different from basinal brines. Inclusion fluids in preore stage show little variation in composition between ~510° and ~430°C, indicative of a closed cooling system. In contrast, the major components of the syn- and postore fluids, including Cl, Na, and K, decrease and correlate with a drop of homogenization temperatures from ~370° to ~200°C, indicating a dilution by mixing with groundwater. The Baiyinnuo'er mineralizing fluids (trapped in sphalerite) have higher Ca/K mass ratios (avg ~0.78) than other proximal magmatic hydrothermal systems (0.06-0.52) but lower than that of the distal El Mochito skarn (avg ~6.4), probably reflecting a gradually weakened magmatic signal away from the causative intrusions. The metal contents in preore fluids are significantly higher than those in synore fluids, but no mineralization occurred. This confirms that the early fluids were, although enriched in metals, not responsible for ore precipitation, most likely due to their high temperature and high salinities. One important factor controlling Zn-Pb mineralization was mixing with groundwater, which resulted in temperature decrease and dilution that significantly reduced the metal solubility, thereby promoting metal deposition. Another main driving force was the interaction with carbonate wall rock that buffered the acidity generated during the breakdown of Zn and (Pb)-Cl complexes and the precipitation of sulfides. Phase separation occurred in both the preore and the early part of the synore stages, but no evidence indicated that it caused metal deposition. The prograde minerals and retrograde minerals (including ore minerals) coexisting in the same samples could have been caused by two (or more) successive pulses of hydrothermal fluids released from residual melts of a progressively downward crystallizing magma. Each fluid produced a series of proximal high-temperature prograde to distal low-temperature assemblages, with the lower temperature assemblages of later fluids overprinting the higher temperature assemblages at most locations. [ABSTRACT FROM AUTHOR]

We present high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-IDTIMS) U-Pb zircon and isotope dilution-negative-thermal ionization mass spectrometry (ID-N-TIMS) Re-Os molybdenite geochronology of the world-class Tibetan Qulong porphyry Cu-Mo deposit. The data is used to constrain the timing, duration, and to yield implications for the ore-forming processes. The U-Pb data suggest that the preore Rongmucuola pluton crystallized at 17.142 ± 0.014/0.014/0.023 Ma (uncertainties presented as analytical/+ tracer /+ decay constant uncertainties), with emplacements of the synore P porphyry and postore quartz diorite occurring at 16.009 ± 0.016/0.017/0.024 and 15.166 ± 0.010/0.011/0.020 Ma, respectively. The Re-Os analysis of multiple independent molybdenite separations from single molybdenite-bearing quartz veins yields sub-%c level analytical precision (

The Maw zone rare earth element (xenotime) deposit is hosted in brecciated sandstones in the Athabasca Basin and is associated with silicification, hematitization, and tourmalinization (magnesiofoitite). Petrographic studies indicate that xenotime precipitated after significant compaction of the host rocks and was coeval with the main phase of tourmaline and drusy quartz. Sensitive high-resolution ion microprobe U-Pb dating of xenotime yielded a 207Pb/206Pb age of 1547 ± 14 Ma. In situ secondary ion mass spectrometry oxygen isotope analysis of coeval tourmaline and quartz gives temperatures from 89° to 385°C (average 185°C) and δ18Ovsmsow-Fluid values from -6.2 to +10.8? (average +1.6%). The coexistence of different types of fluid inclusions (liquiddominated biphase, vapor-dominated biphase, vapor only, and halite-bearing triphase) in individual fluid inclusion assemblages in drusy quartz suggests boiling and heterogeneous trapping. Excluding the heterogeneously entrapped fluid inclusions, the liquid-dominated biphase inclusions yielded homogenization temperatures from 63° to 178°C, ice-melting temperatures mainly from -37.4° to -21.8°C, and salinities mainly from 22.0 to 28.3 wt %. Raman spectroscopic and mass spectrometric analyses indicate low nonaqueous volatile concentrations (<1 mole %). In conjunction with regional stratigraphy indicating burial depth less than 2.5 km at the time of mineralization, these data suggest an epithermal mineralization environment. The similarities in wall-rock alteration, paragenesis, mineralization age, oxygen isotopes, and fluid inclusion attributes between the Maw zone rare earth element deposit and unconformity-related uranium deposits in the region invokes a possible genetic link between them. The hydrothermal fluid at Maw zone probably represents one of the fluids that carried reducing agents and caused uraninite precipitation in the unconformity-related uranium deposits. [ABSTRACT FROM AUTHOR]

We study a carbonate body looking like a classical fossil travertine which was discovered in the Chebaki-Balakhta basin within the Minusa trough (Khakassia, Russia) and called quasi-travertine. It is a thin layer sandwiched between a basalt-dolerite sill and calcareous siltstone. Comprehensive studies of the quasi-travertine and its comparison with Devonian fossil travertines located a few kilometers away in terms of structure and composition have made the basis for its formation model. According to this model, the quasi-travertine has had a two-stage history: deposition and subsequent hydrothermal metasomatism. Laminated limestone coexisting with calcareous siltstone of the Early Devonian Shunet Formation formed during the first stage and then experienced hydrothermal metasomatism with precipitation of secondary calcite, prehnite, and pyrobitumen (kerite). [ABSTRACT FROM AUTHOR]

The investigation of this paper focused on whether the composition of hydrothermal ore-related magnetite in till could be used to locate porphyry deposits in terrane where glacial overburden overlies rocks that host porphyry Cu-Au mineralization. This hypothesis was tested using 20 till samples collected in a -900-km² area surrounding the Mount Polley poiphyry Cu-Au deposit in south-central British Columbia, Canada. At least 100 magnetite grains were randomly selected from the magnetic fraction of each til! sample. Nineteen trace elements in ~50 magnetite grains in each sample were measured by laser ablation-inductively coupled plasmamass spectrometry (LA-ICP-MS). The large beam or raster size used for laser ablation (to 100 μm) homogenizes any heterogeneous trace element distributions in magnetite that result from oxy-exsolution and/or and dissolution/reprecipitation, avoiding this issue with the few micron size of an electron beam. Linear discriminant analysis (LDA) performed on a compilation of magnetite compositions measured by LA-ICP-MS from worldwide porphyry deposits and intrusive igneous rocks define the chemical signature (Mg, Al, Ti, V, Mu, Co, Ni) of hydrothermal magnetite exclusive to porphyry systems. Application of our twc LDA models to the 985 magnetite compositions we measured in the till samples surrounding Mount Polley showed anomalous amounts of hydrotnermal magnetite grains in till up to 2.5 km west-southwest and 4 km northwest of the deposit--a pattern that is consistent with the ice-dow history of the region. Our LDA models for magnetite trace element compositions have strong potential to be an effective tool in exploration for buried porphyry systems. [ABSTRACT FROM AUTHOR]

In hydrothermal ores, gold is commonly hosted by sulfide minerals due to its affinity for reduced sulfur. In contrast the occurrence of gold in oxide minerals remains poorly documented and incompletely understood. In this contribution, we demonstrate that magnetite can be a significant host mineral for gold. Skarn ores from the giant Beiya Au deposit (323 t Au at 2.47 g/t), southwest China, contain abundant nanometer-to micronsized gold hosted by magnetite. A range of bismuth minerals (e.g., native bismuth, maldonite, and bismuthinite) occur within the same assemblage. Textural and mineralogical studies as well as thermodynamic modeling indicate that Bi melts scavenged Au from hydrothermal fluids during magnetite growth. Fluetuating fo2(g) at the surfaces of crystallizing magnetite led to the precipitation of Bi-Au melt, ongoing gold refinement, and entrapment of gold and bismuth minerals within magnetite. Sulfidation of Bi, triggered by increased sulfur content and/or decreased temperature, further promoted gold precipitation. Bismuth melts are interpreted to have played a crucial role in Au enrichment from gold-undersaturated fluids at Beiya. The results imply that magnetite-rich systems are also potential targets for Au exploration and extraction, particularly in cases where coexisting Bi minerals are observed in abundance. [ABSTRACT FROM AUTHOR]

The basak-hosted Semenov-2 hydrothermal field on the Mid-Atlantic Ridge is host to a rather unique Cu-Znrich mass.ve sulfide deposit, which is characterized by high Au (up to 188 ppm, average 61 ppm, median 45 ppm) and Ag (up to 1,878 ppm, average 490 ppm, median 250 ppm) contents. The largest proportion of visible gold is associated with abundant opal-A, winch precipitated after a first generation of Cu, Fe, and Zn sulfides and before a second generation of Fe and Cu sulfides Only rare native gold grains were found in earlier sulfides. Fluid inclusions in opal-A associated with native gold indicate precipitation at 300° ± 40°C from fluids of s;dinity higher than that of seawater (3.5-6.8 wt % NaCl equiv). According to laser ablation-inductively coupled plasma-mass spectrometry analyses, invisible gold is concentrated in secondary covellite (23-227 ppm) rather than in the primary sulfides (<1 ppm). Silver minerals (native silver, stutzite, and naumannite) rarely occur in the sulfides and in aragonite associated with opal-A; invisible silver was detected in all sulfides, but, again, covellite contains more Ag (>1,000 ppm) than all other sulfides (<250 ppm). Covellite replacing Zn sulfides (eovellite-A) is enriched in all analyzed trace elements relative to covellite replacing Cu-Fe sulfides (covellite-B). The enrichment of covellite-A in trace elements may be related to the dissolution of inclusions of various minerals hosted in former sphalerite, which were the source for Au and Ag (native gold), Pb and Tl (galena), 3e (chalcopyrite, Se-bearing galena, naumannite), Te and Bi (Bi tellurides), As (tennantite, ehalcopyrite), and Sb (tennantite). The formation of covellite-A was favored by hydrothermal fluid/seawater mixing or direct oxidation of sulfides by seawater, as suggested by the relatively high contents of typical "seawater" elements (U and V). The degree of seawater involvement was apparently lower for covellite-B. Although the Semenov-2 field is basalt hosted, several geochemical features of the massive sulfides studied are similar to those of the Mid-Atlantic Ridge ultramafic-hosted Cu-Zn-rich massive sulfides, such as Fe:Cu:Zn ratios close to 1:1:1, high Sn, Se, Au, and Ag contents, and high Au/Ag ratios. However, the strong enrichment in SiC>2, the moderate Mn and Co contents, very low Ni contents, and the Co/Ni ratio >1 are more consistent with a mafic signature. Thermodynamic modeling of hydrothermal fluids produced by reactions between various proportions of seawater and basalt or peridotite at 350°C shows that mineral assemblages broadly similar to those of the Semenov-2 deposit can precipitate from fluids produced in a mafic environment, but that Au and Ag minerals are not predicted to precipitate from such fluids ever a wide temperature range. These results suggest that an additional contribution to the hydrothermal system is required in order to achieve saturation in precious metals. A magmatic input is suggested by the occurrence of plagiogranites mid tonalites dredged on sea floor in the Semenov area, which cou.d be a potential source of Au-rich magmatic fluids, and by mineralogical and geochemical similarities with magma-related, low- to intermediate-sulfidation epithermal systems, namely high Au and Ag grades, high Au/(Cu + Zn + Pb) and Au/Ag ratios, and presence of Ag, Bi, and Te minerals. The likely crucial role of silicic melts in producing high Au and Ag grades suggests that exploration for precious me:al-rich, volcamc-hosted massive sulfide deposits should be primarily directed to sites in which evolved igneous rocks occur on sea floor. Both in modem and ancient mafic-hosted deposits, zones characterized by abundant deposition of silica could be good clues to the presence of significant gold. [ABSTRACT FROM AUTHOR]

In this study, Fe,Mn-C porous /CF materials were successfully fabricated by calcination of hydrothermal-produced MIL-100(Fe,Mn)/CF material in N 2 gas and applied as an effective cathode in the electro-Fenton (EF) decomposition of Methylene Blue (MB) in water. The characteristics of the materials were analyzed by SEM, XRD, EDX, FTIR, XPS, and TGA-DTG methods. The removal efficiencies of MB, COD, and TOC after 60 min were 98.49%, 81.80%, and 61.35%, respectively, under the conditions: MB concentration of 20 mg/L, Na 2 SO 4 concentration of 50 mM, current density of 13.33 mA.cm−2, pH 3, and temperature of 25 °C. The effects of some anions on the MB removal efficiency were examined and in the order of SO 4 2- < Cl- < NO 3 - < HCO 3 - < HPO 4 2-. Radical quenching tests demonstrated the formation and active roles of •OH as the dominant radical. The excellent stability and reusability of the electrode under optimal operating conditions make it great potential for practical applications in the treatment of wastewater containing recalcitrant organics. The EF process was also tested for various water matrices and types of dyes to test its practical application. The mineralization and the ecotoxicity of the treated wastewater were also studied. The mechanism of the EF process using Fe,Mn-C porous /CF cathode, and the degradation pathway of MB during the EF process were proposed. [Display omitted] • Fe,Mn-C porous /CF was prepared as an effective cathode for electro-Fenton process. • Comprehensive study on the effects of reaction conditions on organic removal. • OH is the key reactive oxygen species evidenced by radical quenching test. • Electro-Fenton reaction mechanism and organic degradation pathway were proposed. [ABSTRACT FROM AUTHOR]

• The relationship between pH and pO 2 is investigated for ocean water masses. • pH and pO 2 are poorly correlated in Arctic water masses. • Hydrothermal vents affect the chemistry of a large portion of the water column. • The findings have implications for the planning of GCS leakage monitoring. In the absence of abiotic sources of CO 2 , variation in pCO 2 and pO2 is expected to be inversely correlated in the water column due to biogenic processes. It has previously been suggested to use this correlation for leakage monitoring of offshore geological carbon storage (GCS) sites. In this study the aim is to investigate the extent of this correlation in ocean water masses with different origin and history in the Norwegian Sea, as well as in water masses in the vicinity of an active hydrothermal vent field at Mohn's Ridge, where pH is used as a proxy for pCO 2. Over a hydrothermal vent site, a strong correlation between pH and pO2 is observed from 0 to 1700 m, whereas at depths >1700 m there is no correlation, likely due to CO 2 emissions from the hydrothermal vents. However, at a reference site nearly 200 km from the hydrothermal vents, the intermediate Arctic water masses (700 – 1600 m depth) also show pH-pO2 correlations that are inconsistent with biogenic processes, but less pronounced compared to the hydrothermal vent site. These findings show that the suitability of this monitoring strategy will depend on a thorough site-specific evaluation of pH/CO 2 and O2 relationships of relevant water masses. [ABSTRACT FROM AUTHOR]

A new type of green carbon quantum dots (ILB-CQDs) was prepared by hydrothermal method using ionic liquid as a modifier and grape skin as carbon source, and was obtained from hydrogen-bonded lattice structure ionic liquid preparation, which makes the CQDs in a ring-like stable structure with a stability period of more than 90 day. There is also the catalytic effect of the ionic liquid on cellulose, which makes the prepared CQDs show good advantages, such as uniform particle size, high quantum yield (26.7%), and very good fluorescence performance. This is a smart material for the selective detection of Fe3+ and Pd2+. It has a detection limit of 0.001 nM for Fe3+ and 0.23 µM for Pd2+ in pure water. It has a detection limit of 3.2 nmol/L for Fe3+ and 0.36 µmol/L for Pd2+ in actual water, both of which meet the requirements of WHO drinking water standards. And there is to achieve more than 90% of water restoration effect. [Display omitted] • Modification of biomass with ionic liquids increased the quantum yield from 9.7% to 26.7%. • The material has different detection mechanisms for Fe3+ and Pd2+ in real water bodies. • It can produce precipitation for both Fe3+ and Pd2+, so it has more than 90% restoration rate when restoring water bodies. • The catalytic effect of ionic liquid and nitrogen doping were found in the preparation of carbon quantum dots. [ABSTRACT FROM AUTHOR]

The Cu-Sb-Pb polymetallic vein deposit is hosted by metavolcanics rocks of the Gawuch Formation at the Kaldom Gol area of the northwest Kohistan arc terrain in northern Pakistan. The mineralization is closely associated with the dioritic to granodioritic rocks of the Lowari pluton, which was intruded into the Gawuch metavolcanics. Details of ore characterization and processes of ore genesis of this evidently hydrothermal mineralization are not well documented. Integrating petrographic, mineral-chemical and isotopic investigations, this study aims to comprehend the source of hydrothermal fluids, geochemical evolution, mineral inclusions and physicochemical conditions of the Cu-Sb-Pb polymetallic vein deposit in Gawuch metavolcanics in the Kohistan arc terrain in northern Pakistan. The mineralization is distinguished into three types of ore-gangue associations: Type Ia, Type Ib, and Type II. The textural study revealed two pyrite generations: (i) Py1 displaying euhedral to subhedral habits and containing scarce inclusions, and (ii) Py2 occurring as anhedral grains hosting abundant inclusions. Type Ia is characterized by Py1 associated with abundant quartz (Qz) showing comb texture, sericite (Ser), and minor chlorite (Chl). Type Ib comprises Qz + Ser + Chl and Py2, chalcopyrite (Ccp), and magnetite (Mag). Type II is represented by mosaic quartz, rhombic adularia, and bladed calcite, and the ore minerals fahlore and galena. Alteration zones composed of Qz-Ser ± Chl and Qz-Ser-Chl, surround Type I (a, b) and Type II veins, respectively. Fahlore and galena mostly replace pyrite of Type Ia and chalcopyrite of Type Ib. In addition, malachite, azurite, hematite and covellite occur as secondary (supergene) minerals. The Co/Ni ratios (>1) of Kaldom Gol pyrites suggest that the ore-forming fluids were hydrothermal in origin and Py1 and Py2 solidified at 221–304 °C and 225–261 °C, respectively. The LA-ICP-MS time-resolved depth profiles confirm the existence of sphalerite, and chalcopyrite inclusions in pyrite (Py1 and Py2) and millerite , bravoite , vaesite , Au-tellurides, native Au and galena inclusions in chalcopyrite and fahlore. Sulfur isotope compositions of pyrites (δ34S = Py1, −0.58 to +2 ‰; δ34S = Py2, −0.24 to +2.04 ‰) indicate that the ore-forming fluids were derived from magmatic source (s). The mineral assemblage, hydrothermal alterations, textures, temperature and δ34S of pyrites suggest that the Cu-Sb-Pb polymetallic mineralization at Kaldom Gol represents an intermediate-sulfidation type of epithermal deposit. [Display omitted] [ABSTRACT FROM AUTHOR]

The Noion-Tologoi polymetallic deposit corresponds to the Akatui type of polymetallic deposits of eastern Transbaikalia. These deposits are associated with volcanoplutonic rocks of the Akatui complex. In element contents the polymetallic ores of the Noion-Tologoi deposit are similar to ores of volcanohydrothermal (VHMS type) deposits of southern Siberia. The orebodies are tabular, stockwork- and vein-like. They are localized in fault zones. The ores contain, on the average, 4.9% Pb, 6.8% Zn, and 272 ppm Ag. The most common ore minerals are pyrite, galena, arsenopyrite, and sphalerite. The δ 18 O (SMOW) values in the ore quartz range from -3.9 to + 10.6‰. The isotopic composition of oxygen in the fluid (at 250-275 °C) varies from -12.80 to + 2.79‰, indicating the participation of meteoric waters in mineralization. The enclosing rocks are volcanoterrigenous deposits of the Mulino Group (J 2-3 ) and syenite porphyry of the Akatui complex (J 2-3 ). In geochemical characteristics the syenite porphyry is similar to adakite intrusions. The Rb-Sr isotopic age of syenite porphyry is 150 ± 9 Ma. The initial ratio of strontium isotopes in these rocks is ( 87 Sr/ 86 Sr) 0 = 0.70698 ± 0.0004, which indicates their mantle-crustal source. [ABSTRACT FROM AUTHOR]

Warri is one of the mega cities in Delta State in the coastal region of Nigeria hosting many industries. One of the three of Nigeria oil refineries is located in Warri. This study reveals the occurence of land deformation in the Warri area which is not only because it was formed in a tectonic setting but because of the high demand of the underground water for indutrial and domestics uses, high population density and oil and gas exploration in the area. Land deformation in this area is currently being accelerated by this indiscriminate withdrawal of underground water from the aquifers and exploration of the oil and gas leading to the compacting sediments. In this study Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique was applied to monitor land deformation in Warri metropolis in the period between 09/02/2006 and 12/08/2010 with Envisat data obtained from European Space Agency (ESA). The processing was done using Stanford Method for Persistent Scatterers/Multi-Temporal InSAR (StaMPS). From the analysis of the results, land deformation is occurring in Warri metropolis at a moderate rates (±5 mm/yr). During the preliminary investigations, structures, particularly buildings, were physically observed subsiding while some others with cracks of various types and degrees. [ABSTRACT FROM AUTHOR]

The Hattu schist belt is an emerging gold-producing ore district in the western part of the Archean Karelian Province of the Fennoscandian Shield. The belt consists of 2.76 to 2.70 Ga tonalite, granodiorite, and leucogranite intruded into a mafic-felsic epiclastic-volcanic sequence of an only slightly older age. Complex and successive folding, shearing, and hydrothermal processes affected these rocks prior to the lower amphibolites facies peak metamorphism (550° ± 50°C; 3-5 kbar) at ca. 2.70 Ga. Orogenic gold deposits are hosted by the highly strained zones that developed during the Archean deformation of the belt. However, previous K-Ar and Rb-Sr geochronological studies indicated that a second tectonothermal overprint affected the Hattu schist belt between 1.7 and 1.8 Ga during the Svecofennian orogeny. Results of our field, mineralogical, textural, and Pb isotope studies suggest that ore deposition at Pampalo was initiated by hydrothermal processes at the time of the emplacement of feldspar porphyry and tonalite intrusions and dikes, at around 2.72 Ga. Albitization and quartz-tourmaline-biotite-muscovite veining characterize this hydrothermal activity. The major stage of gold ore deposition can be confined to the subsequent development of high-strain zones in an intermediate-felsic tuffaceous unit (mafic schist) characterized by biotite-carbonatepyrite alteration. Ar-Ar studies revealed the complete resetting of the Ar-Ar system in muscovite and biotite due to the Svecofennian orogeny, with closure of the isotopic system at 1.81 Ga. Results of Pb isotope studies of hydrothermal K-feldspar, galena, and altaite by laser ablation-inductively coupled plasma-mass spectrometry indicate that K-feldspar alteration and remobilization of metals also took place during the Svecofennian reactivation of high-strain zones. The petrographic manifestation of this process is the replacement of albite by hydrothermal K-feldspar. Fluid inclusion data from hydrothermal K-feldspar suggest that carbonic-aqueous, low-salinity fluids interacted with the Archean ore at 350° to 400°C and 1.8 to 2.4 kbar during the Svecofennian overprint. Results of mass transfer calculations indicate that potassium gain correlates with increase of gold concentrations in the mafic schist and feldspar-porphyry units. Therefore, the Svecofennian overprint locally also enhanced the grade of gold mineralization, mostly along competency differences of the mafic schist and feldspar porphyry blocks/dikes. Later percolation of relatively low temperature (<300°C) saline basin fluids in some fractures of the crystalline basement also left their Pb isotope and fluid inclusion signatures on the mineralization while further modifying the composition of the ore. Occurrences of hydrothermal proto-ores, as well as fluid flow events along structures reactivated by overprinting orogenic processes, are not exceptional features in Archean orogenic gold provinces. This study shows that the combination of in situ Pb isotope studies of U-poor alteration minerals and Pb-rich ore minerals, together with evaluation of relationships between gold enrichment and hydrothermal alteration and fluid inclusion studies, can be very useful in determining the significance and conditions of overprinting processes, as well as their potential implications for genetic and exploration models. [ABSTRACT FROM AUTHOR]

Gold- and silver-containing pyrites of the Tikhii area at the Julietta deposit (Engteri ore cluster, Magadan Region) were studied by optical and scanning electron microscopy and electron probe microanalysis. One- or two-phase rounded microinclusions consisting of electrum (450-680%c) and/or galena or of petrovskaite and/or uytenbogaardtite, galena, and sphalerite have been found in early pyrites. Later As-pyrites (up to 2.6 wt.% As) contain multiphase xenomorphic microinclusions of acanthite, uytenbogaardtite, freibergite, argentotetrahedrite-tennantite, naumannite, petzite, selenopolybasite-selenostephanite, tellurocanfieldite, and other ore minerals localized in pores, cracks, and interstices. Pyrites that underwent hypergene alterations have rims and veinlets formed by acanthite, goethite, anglesite, plattnerite, and native silver. The presence of rounded ore mineral microinclusions and large pores in the early pyrites suggests the participation of volatiles in the mineral formation and the uptake of large amounts of impurities by pyrite under high-gradient crystallization conditions. The thermobarogeochemical studies of fluid inclusions in quartz have shown that the ore zone formed under boiling-up of hydrothermal medium-concentration NaCl solutions at 230-105 °C. The results of thermodynamic calculations evidence that Ag-Au-S-Se minerals formed under decrease in temperature and fugacity of sulfur (log 1 Q/S 2 = -22 to -9) and selenium (log 1 Q/S e2 = -27 to -14) and change of reducing conditions by oxidizing ones in weakly acidic to near-neutral solutions. [ABSTRACT FROM AUTHOR]

Al 2 (MoO 4 ) 3 could be synthesized using two different methods, the traditional solid-state reaction and the hydrothermal reaction with post-heating. For preparation by the solid-state reaction, the starting materials were Al(OH) 3 and MoO 3 . TG-DTA results suggested that the reaction temperature of the solid-state reaction should be more than 973 K for crystallization of Al 2 (MoO 4 ) 3 . In contrast, the hydrothermal technique required crystallization at lower temperatures. SEM photographs indicate that while the former yields larger particles, the latter yields finer and well-shaped particles. It is hoped that Al 2 (MoO 4 ) 3 obtained by this method will find applications in the manufacture of ceramic devices. [ABSTRACT FROM AUTHOR]

Juvenile 1.89 Ga oceanic arc volcanic rocks of the Flin Flon volcanic belt at Snow Lake are characterized by extensive zones with anomalous 1.82 Ga metamorphic mineral assemblages, including porphyroblasts of garnet, staurolite, amphibole, biotite, gahnite, and/or kyanite. They were produced from altered rocks created during premetamorphic, 1.89 Ga, synvolcanic, hydrothermal fluid-rock interaction. Three separate episodes of hydro-thermal alteration are recognized that span evolution of the host volcanic rocks from a primitive (nascent arc?) to mature arc geotectonic setting. The geologic, geochemical, mineralogical, and isotopic attributes of the zones indicate that they include volcanogenic massive sulfide (VMS)-related alteration, and they were produced at high and low temperatures and formed in seafloor/near seafloor and subseafloor (intrastratal) environments. Large-scale alteration zones at Snow Lake are up to 20 km in strike length and 0.8 km wide. Their large exploration "footprint," which is 36 times greater in areal extent compared to associated "pipe-like" alteration zones, means that such zones provide a useful target to "vector-in" exploration to VMS depositional settings within volcanic belts. The VMS-related large-scale alteration zones at Snow Lake display diagnostic variations in intensity and style of alteration along strike toward VMS deposits, are stratigraphically underlain by altered portions of synvolcanic intrusions, are crossed by discordant zones of more intensely altered rocks, and can be demonstrated to have formed by interaction with high-temperature(>350°C) hydrothermal fluids. Cu-Zn-rich VMS deposits at Snow Lake formed in flow-dominated sequences, are hosted by large rhyolite flow complexes, and comprise lensoid orebodies. In contrast, Zn-Cu-rich VMS deposits, although also rhyolite associated, formed in voleaniclastic-dominated sequences, are spatially related to a district aquifer, and comprise stratiform, laterally continuous orebodies. This suggests that exploration for Cu-Zn VMS deposits could selectively target flow-dominated sequences and focus on rhyolite flow complexes that display significant alteration. Similarly, exploration for Zn-Cu VMS deposits could focus on volcaniclastic-dominated sequences in which a potential aquifer has been identified. [ABSTRACT FROM AUTHOR]

Novel Ag 3 PO 4 /CNFs/silica-fiber composite photocatalyst was successfully synthesized via a facile combined chemical vapor deposition (CVD) technique and hydrothermal process. The as-prepared Ag 3 PO 4 /CNFs/silica-fiber was characterized by X-Ray diffraction, field emission scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity of Ag 3 PO 4 /CNFs/silica-fiber was evaluated by the degradation of rhodamine B (RhB) under visible-light irradiation. Note that the existence of unique featured CNFs not only has good adsorption ability for RhB molecules, but also benefits to the effective separation of photogenerated electron–hole pairs and thus improves the photocatalytic performance of the catalyst. Specially, the as-prepared Ag 3 PO 4 /CNFs/silica-fiber photocatalyst can easily reduce the cost for the practical application of Ag 3 PO 4 photocatalyst. The new synthetic procedure is simple and could be applicable to a large number of efficient and inexpensive visible-light-driven photocatalytic materials. [ABSTRACT FROM AUTHOR]

The Guelb Moghrein Cu-Au deposit occurs within metacarbonate bodies derived from sedimentary carbonate beds of probable late Archean age. The metacarbonate lenses are enclosed within mafic meta-igneous rocks that display a coarse-grained, amphibolite-facies (homblende-albite) assemblage that is mineralogieally anomalous relative to the greenschist-facies metamorphic rocks present regionally within the district and may represent a zone of synmetamorphie hydrothermal metasomatism. Crosscutting relationships and textural evidence for progressive replacement of different mineral assemblages demonstrate that the deposit had a complex, multiphase alteration-mineralization history. Early sodic alteration at Guelb Moghrein resulted in the formation of albitized zones along moderately to shallowly dipping structures. Sodic alteration was followed by syndeformational ferroan potassic alteration that resulted in the growth of biotite and grunerite-cummingtonite in meta-igneous rocks and conversion of calcite-dolomite in metacarbonate bodies to ankerite- and siderite-rich assemblages. Progressive alteration resulted in breakdown of siderite to magnetite and graphite at approximately 400° to 450°C. Sulfide mineralization took place at ca. 2.5 Ga, concurrently with or shortly after ferroan potassic alteration and magnetite-graphite formation. An early assemblage of Co-, Ni-, and As-rich sulfide minerals was followed by precipitation of pyrrhotite and chalcopyrite. Sulfide mineralization was focused within brittle deformation zones along the margins of the metacarbonate bodies, which represent high-permeability zones adjacent to more ductile structures. The nucleation of sulfides on graphite during siderite breakdown suggests redox reactions may have largely controlled sulfide precipitation. A late magnesian alteration event at ca. 1.74 Ga resulted in the formation of chlorite-rich shear zones and precipitation and/or recrystallization of sulfides. The Guelb Moghrein deposit is a member of the iron oxide Cu-Au class of deposits but is unusual in being hosted in carbonate strata. [ABSTRACT FROM AUTHOR]

The diopside-allanite veins and apatite breccia veins of the Hoidas Lake light rare earth element (LREE) deposit in northern Saskatchewan, Canada, represent a complex magmatic-hydrothermal system unrelated to its strongly deformed Archean and Paleoproterozoic host rocks in the Rae subprovince. The veins were emplaced along the Hoidas-Nisikkatch fault, a subsidiary of the deeply rooted Black Bay fault system, which likely provided pathways for the melts and fluids. Allanite in the diopside-allanite veins is concentrically zoned, reflecting rare earth element (REE) depletion, followed by REE enrichment. Later apatite breccia veins comprise multiple apatite generations. Graphic-textured inclusions in the earliest red apatite indicate the presence of a melt during apatite growth. The average total rare earth oxide (TREO) content increases from 1.5 wt % in the red apatite to 5.5 wt % in the green apatite, both dominated by Ce. In contrast, the latest generation, coarse red apatite, contains about 1 wt % TREO and is Nd dominant. This shift from Ce- to Nd-dominant apatite might reflect a transition from magmatic to hydrothermal growth. Interaction with hydrothermal fluids resulted in chlorite-hematite alteration and REE redistribution into secondary monazite, REE carbonates, REE-Sr carbonates, and allanite, the last occurring in late quartz-carbonate veins and containing up to 32.9 wt % TREO. The chemistry of the REE-bearing phases and their connection with hyalophane-bearing pegmatites and later lamprophyre dikes indicate a mantle-derived, most probably carbonatitic or syenitic source for the mineralizing melts and fluids. [ABSTRACT FROM AUTHOR]