Formation Of Deposits Research Articles

Formation of giant copper deposits driven by rapid uplift and sudden depressurization

Abstract Porphyry Cu deposits (PCDs) in collisional orogens are new targets for modern mineral exploration. A series of post-collisional (Miocene; 22-12Ma) porphyry copper deposit (PCDs) with Cu reserve over 45 Mt have been discovered in the Gangdese magmatic belt, southern Tibet. These magmas derived from partial melting of sulfide-bearing Tibetan juvenile lower crust are fertile for porphyry Cu in many aspects, such as high oxidation state, and rich volatiles such as water, S, and Cl, but some of individual plutons ended up with economic concentrations. The fundamental question remains what accounts for the significant Cu endowments. We measured the igneous zircon water contents of ore-related and barren high Sr/Y magmas in the Gangdese belt, southern Tibet and found that magmas that produce giant PCDs have lower zircon water contents than barren and small-deposit related magmas. Combined with previous fluid inclusions, magmatic breccias, apatite geochemistry, and thermal histories, which demonstrated higher initial water content in causative porphyries such as giant deposits of Qulong and Jiama, we believe that the lower zircon water content may be attributed to these magmas experiencing of faster cooling and sudden depressurization of a large, primed, volatile-saturated or supersaturated mid-upper crustal magma chamber, which could lead to rapid and voluminous volatile exsolution and fluid discharge. These processes caused intense hydrothermal alteration and large ore deposition. In contrast, magmas that experienced slow cooling and deep emplacement would undergo steady state degassing and weak alteration. The variable intrusive and thermal histories across Gangdese reflects interplay between surface and lithospheric dynamics within the Himalaya—Tibet orogen. Our findings suggest the difference of zircon water content reflects the emplacement rate and depth of granitic body, and therefore may serve as an indicator for tectonics and potential for mineralization.

Diversity of critical minerals deposits in the North American Cordilleran alkaline-igneous belt in southern Colorado, New Mexico, Texas, and Mexico

Critical minerals are nonfuel mineral commodities that are essential to the economic and national security of the United States and many other countries, mostly imported into the U.S., and are from a supply chain that is vulnerable to global and national disruption. A renewed interest in critical minerals in the U.S. and the world has become the focus of research in understanding ore formation, mineral-resource potential, and ore production of these important mineral deposits. Alkaline igneous rocks, including carbonatites, are known for their associated critical minerals deposits. The North American Cordilleran alkaline-igneous belt is one such area known for gold, molybdenum, rare earth elements (REE), and critical minerals deposits associated with Eocene-Miocene (45.6 to 22.8 Ma) alkaline igneous rocks and carbonatites. The belt extends southward from Alaska and British Columbia into New Mexico and eastern Mexico. Gold, molybdenum, and critical minerals such as REE, tellurium, fluorine, zirconium, and niobium have been found and locally exploited along this belt. In New Mexico (the focus of this paper), the belt extends southward from the Sangre de Cristo Mountains to the Cornudas Mountains, in the northern Trans-Pecos alkaline belt. The mineral deposits in the North American Cordilleran alkaline-igneous belt are controlled by composition and source of alkaline magmas, regional and local structures, and development of multiple hydrothermal systems during the transition from Laramide compression (75-40 Ma) to Rio Grande rift extension (28-5 Ma). Three predominant types of mineral deposits are found in the North American Cordilleran alkaline-igneous belt: (1) alkalic-type epithermal gold, (2) Climax-type porphyry molybdenum, and (3) magmatic REE deposits (including veins and breccia deposits in adjacent host rocks); a fourth deposit type, small alkalic porphyry copper-gold deposits, are found in a few districts. Many of the mineral deposits in this belt formed at or after peak activity of a local magmatic cycle. Magmas and sulfur were derived from melting of the lower crust to upper mantle (as indicated by isotopic data from several deposits) resulting in the diversity of mineral deposits in the southern North American Cordilleran alkaline-igneous belt. Most of the magmatic REE deposits occurred during the transitional period (40-28 Ma), whereas the Climax-type porphyry molybdenum deposits occurred mostly at the beginning of rifting (25-24 Ma). The alkali epithermal gold and small alkalic porphyry deposits occurred at the end of the Laramide orogeny and during the transitional period before rifting. Most alkalic-type epithermal gold deposits in New Mexico are found in hydrothermal breccia pipes and skarns with anomalous, but uneconomic concentrations of REE and tellurium. Alkalic-type epithermal and alkalic porphyry copper-gold deposits in New Mexico are found in the Ortiz Mountains in Santa Fe County (Carache Canyon, Lucas Canyon). Many districts in the belt have future critical minerals potential. Tellurium is found at Cripple Creek, Colorado and Organ Mountains, New Mexico. Tungsten was locally produced in the past from two of these gold deposits (Elizabethtown and White Oaks) and is found in the Ortiz Mountains deposits. The Climax-type molybdenum deposits, including the Questa deposit, contain anomalous, but uneconomic concentrations of beryllium and fluorite. The magmatic REE deposits in Laughlin Peak, Gallinas, Capitan, and Cornudas Mountains, New Mexico generally contain anomalous, but uneconomic concentrations of zircon, niobium, fluorite, and gold, and generally low tellurium, tungsten, and beryllium concentrations. The magmatic REE deposits in the Gallinas Mountains are among the highest ranked deposits for economic potential for REE in New Mexico; some samples contain as much as 8% total REE. Some samples in the Cornudas Mountains contain as much as 3110 ppm total REE, mostly in eudialyte. A mineral concentrate of the REE-bearing minerals (eudialyte, zircon, monazite, bastnäsite, calcio-catapleiite, vitusite, roumaite, xenotime) could be obtained after mining by magnetic separation and REE could be leached from that concentrate.

Calculation model of enjoyment of dust particles by swirking flow in gas flowes

An analysis of the reasons for the formation of deposits in the flue ducts of aspiration systems was carried out. Problems have been noted in removing deposits with compressed air. The purpose of the work is to solve the problems of aspiration systems and reduce the formation of dust deposits in gas ducts. This is possible due to the swirling of the compressed air flow when purging the gas duct. Despite significant pressure losses when organizing flow swirl, compressed air consumption is reduced by 20–40%. A computational model of the entrainment of dust particles by a swirling flow in gas ducts is presented. To describe the physical model of the movement of a dust particle in a swirling gas flow flowing in a gas duct with a circular cross-section, polar coordinates are used. Dependencies have been deter-mined to determine the value of the average axial velocity of the swirling flow required to move a particle along the gas duct. A diagram of the coordinate axes and forces acting on the particle is presented. The forces acting on the dust particle and its connections with the inner surface of the flue are replaced by the reaction of the flue wall. By decomposing the wall reaction into tangential and normal components, differential equations were obtained that describe the motion of the particle. The dust particle is significantly influenced by the forces of resistance to flow around the gas flow Fμ, the friction force on the wall of the gas duct Ffr, the weight of the particle P, the normal reaction of the wall of the gas duct N. Analysis of the fractional composition of various dusts contained in gases aspirated from the equipment of the metallurgical industry and the production of electrode materials showed that For these dusts, the optimal flow is a weak swirl of intensity W*= 0.5–0.8. This swirling intensity can be achieved by introducing a flow of compressed air when blowing at an angle of 36–48°.

Insights into the synergistic effects of tectonics and climate from the formation and evolution of the Hongwen allochthonous deposit, southwestern China

Abstract The formation and evolution of large-scale deposits generated by mass movement are often closely related to tectonic and climatic conditions. Investigating deposits under the influence of complex geological conditions can aid in reconstructing paleoenvironmental characteristics and fluvial geomorphic evolution. The First Bend of the Yangtze River (FBYR), located in the Jinsha River basin in southwest China, represents a significant section characterized by abundant allochthonous deposits. We conducted a detailed investigation of the Hongwen allochthonous deposit (HAD) and the river sediments in the First Bend. Through terrain interpretation, dating, and paleoenvironmental analysis, the HAD was determined to be a complex deposit with multiple sources and stages (46.4–33.5 ka), formed under the combined influence of tectonic activity and climate. Three mass-movement events occurred during the interglacial stage of the last glacial period or its transitional period, coinciding with the rapid uplift stage of the Tibetan Plateau since the late Pleistocene. Prominent features of this period include significant rainfall and tectonic activities. By dating fluvial sediments and examining the evolution of the HAD, we revealed a river incision rate of 2.30 mm/yr for the Jinsha River, providing a basis for analyzing periodic river cutting and the development pattern of surface processes.

ENHANCING SURFACE CHARACTERISTICS OF AA2024-T3 AIRCRAFT ALLOY THROUGH SYNERGISTIC ANODIZATION AND CERIUM CONVERSION COATING. PART I: PERFORMANCE IN MODEL CORROSIVE MEDIUM

The present study is devoted to the monitoring of the performance of AA2024-T3 specimens, after the formation of Anodic Aluminum Oxide (AAO) layer and/or deposition of a Ceruim Conversion Coating (CeCC), obtained at 20°C and 50°C, respectively. Although both methods are well described in the literature, there is no sufficient information regarding the effect of their combination on their behaviour in corrosive media. The performance of the respective specimens was elucidated after 24 h of exposure to 3.5 % NaCl model corrosive medium (MCM) by means of Electrochemical Impedance Spectroscopy (EIS) and acquisition of Potentiodynamic Scanning (PDS) curves. Since the combined AAO/CeCC coating primers revealed superior barrier properties, the respective specimens weresubjected to long-term corrosion tests of up to 672 h of exposure to the MCM to evaluate their durability. The results revealed the synergistic effect of the combination of the surface treatment procedures on effective corrosion mitigation.

Porphyry copper formation driven by water-fluxed crustal melting during flat-slab subduction

AbstractThe prevailing view of the formation of porphyry copper deposits along convergent plate boundaries involves deep crustal differentiation of metal-bearing juvenile magmas derived from the mantle wedge above a subduction zone. However, many major porphyry districts formed during periods of flat-slab subduction when the mantle wedge would have been reduced or absent, leaving the source of the ore-forming magmas unclear. Here we use geochronology and thermobarometry to investigate deep crustal processes during the genesis of the Late Cretaceous–Palaeocene Laramide Porphyry Province in Arizona, which formed during flat-slab subduction of the Farallon Plate beneath North America. We show that the isotopic signatures of Laramide granitic rocks are consistent with a Proterozoic crustal source that was potentially pre-enriched in copper. This source underwent water-fluxed melting between 73 and 60 Ma, coincident with the peak of granitic magmatism (78–50 Ma), porphyry genesis (73–56 Ma) and flat-slab subduction (70–40 Ma). To explain the formation of the Laramide Porphyry Province, we propose that volatiles derived from the leading edge of the Farallon flat slab promoted melting of both mafic and felsic pre-enriched lower crust, without requiring extensive magmatic or metallogenic input from the mantle wedge. Other convergent plate boundaries with flat-slab regimes may undergo a similar mechanism of volatile-mediated lower-crustal melting.

Investigation of the steady state subcooled boiling regime in the hot subchannel of a VVER-1200 reactor core: A CFD analysis

A Computational Fluid Dynamics (CFD) analysis is carried out on a three-dimensional subchannel representing the most intensive fuel assembly to simulate the thermal-hydraulic performance of the VVER-1200 hot channel under steady-state operation. It is found that, subcooled boiling is predicted for both the rated and the conservative operational parameters with the intensity of bubble generation found to be higher for the conservative scenario compared with the rated one. The predicted boiling phenomenon at the cladding surface may result in the formation of deposits, and pits, and may impair the strength of the fuel elements, and increase the inhomogeneity in fuel burnup. Therefore; a thorough investigation of the predicted boiling regime is required to shed light on the development of this phenomenon in a typical reactor subchannel using CFD tools. The CFD work conducted in this work is based on the Eulerian multiphase model in ANSYS in conjunction with the RPI wall boiling model. The developed model has been validated against other one-dimensional models found in the literature. The variation of mass-averaged quantities (across the channel) along the subchannel generally agrees with the 1D models, which builds confidence in the modeling approach. Contours showing the spatial variations of temperatures, vapor void ratio, as well as heat fluxes are presented. Profiles of the different components of heat flux during boiling are presented. It has been found that the heat flux variations during boiling pass through three distinct regimes. In the first, a steady increase in quenching and evaporation heat flux is observed, while convective heat flux declines. In the second regime, the quenching and evaporation heat fluxes plateau with a slight decrease, while the convective heat flux becomes zero. This signifies that the outer clad surface is largely covered with vapor bubbles and the only heat transfer mechanisms are due to quenching and evaporation. During the last regime, quenching and evaporation heat fluxes decline due to the decline of the imposed heat flux at the clad surface, and hence convective heat transfer starts to increase. In addition, profiles of the mass-averaged coolant temperature, void fraction, and outer clad surface temperatures along the hot element underrated and conservative operating conditions are also generated.

Metallogenic model of sandstone-hosted copper deposits: a case study from the Paleogene in Jiashi area, northwestern China

Sandstone-hosted copper deposits, a type of Sediment-Hosted Stratiform Copper (SSC) deposits, are widely distributed globally. While economically viable deposits of SSC are relatively scarce, they account for approximately 30 % of the world's total discovered copper resources. However, there is still a lack of comprehensive and in-depth research into the depositional and metallogenic models of these deposits. The Jiashi area of the Tarim Basin in northwestern China, known for its economically significant Paleogene SSC deposit, lacks in-depth studies on metallogenic processes. To address this, field profile observations were conducted to analyze the sedimentary evolution, sequence stratigraphy, and tectonism of the Paleogene strata in the Jiashi area. Combined with elemental geochemical analysis of samples, the provenance of sediment, and the source of metallogenic materials, a robust metallogenic model was established. The results reveal the influence of provenance for the origin of Paleogene copper-rich strata. Sedimentary evolution played a crucial role in controlling the distribution of copper and sulfur elements, as well as the spatial arrangement of metallogenic beds. Additionally, nappe movement potentially generated faults, allowing upward movement of basin fluids, which played a crucial role in the formation of copper deposits within sandstone-hosted systems. Thus, this study offers a comprehensive analysis of the metallogenic processes involved in sandstone-hosted copper deposits, thereby contributing significant insights to the broader research on SSC deposits worldwide.

Magmatic initial and saturated water thresholds determine copper endowments: Insights from apatite F-Cl-OH compositions

Magmatic volatiles (H2O, F, Cl), especially water, are critical in the formation of porphyry copper deposit, for its significance as a carrier for metals. However, accurately quantifying the water contents of deep ore-forming magma remain a challenge. Here, we used apatite and forward modelling methods to reconstruct magmatic water evolution histories, with special concern on the control of initial magmatic H2O contents and water saturation threshold to porphyry mineralization. Samples investigated include granitoid rocks and apatite from highly copper-mineralized and barren localities. Generally, our research suggested that both ore-related and ore-barren magma systems are hydrous, the modeled magmatic water contents vary significantly among systems whether mineralized or not, and the major difference lies in the threshold of water saturation (6.0 wt% for barren, and up to 10.0 wt% for highly mineralized). Combined with whole rock geochemistry data (high K2O and Sr/Y contents) and modeling result (high modeled water thresholds), we think the ore-related magmas are stored at deeper depth with higher water solubility. In conclusion, we propose that the level of magmatic water saturation plays a crucial role in the formation of porphyry copper systems. Fertile magma has higher water solubility to which deeper storage depth is a critical contributing factor, and can get significantly water enriched upon saturation.

Timing of S-saturation in the formation of the Oubulage porphyry Cu-Au deposit, Inner Mongolia, Northern China

The Oubulage porphyry Cu-Au deposit, Inner Mongolia, North China, is located in the Langshan Tectonic Belt on the southern margin of the Central Asian Orogenic Belt (CAOB). The ore-forming quartz porphyry intrusion was formed during the Middle Permian (268.4 ± 1.6 Ma). Randomly and directionally distributed sulfide blebs are observed in some porphyry rocks. These blebs are spherical or ellipsoidal in shape. There are two groups of such blebs: polymetallic sulfide blebs and silicate-carbonate-sulfide blebs. Sulfide minerals in these blebs include pyrite, chalcopyrite, and pyrrhotite. Silicate-carbonate-sulfide blebs also contain calcite, epidote, plagioclase, chlorite, fluorite, and bastnaesite. Pyrite of sulfide blebs has δ56Fe ranging from −0.38 ‰ to 1.19 ‰. Calcite in sulfide blebs has C-O-Sr isotopic compositions (δ13CVPDB = −7.35 – −5.35 ‰, δ18OVSMOW = 8.35 – 9.92 ‰, 87Sr/86Sr = 0.7032 – 0.7064) indicative of a magmatic origin. We propose a new possible genetic model in which sulfide saturation occurred in a magma chamber, leading to the formation of sulfide droplets. Assimilation added sulphur (S) into the magma chamber and caused S-saturation. The sulfide melts are transported to the shallow crust attached by fluids.

Solubility of NaCl in water vapor at 400–700 °C

Water significantly impacts the chemical evolution of the Earth’s crust, affecting environments from volcanic settings to hydrothermal systems. These fluids transport elements essential for geological processes, such as metal ore deposit formation. At high temperatures, as water transitions from liquid to vapor, its molecular structure changes, drastically reducing its capacity to dissolve solids and solvate ions. Here, we report experimental results of halite (NaCl(s)) solubility in water vapor at 400–700 °C and 30–300 bar using a novel U-tube flow-through reactor system. The results show that halite solubility is low (xNaCl,tot = 3.2 × 10−9 to 2.9 × 10−4 mol/mol) and increases with temperature and pressure, attributed to the dissolution of NaCl followed by its hydration according to the reaction:NaCl(s)+nH2O(g)⇋NaCl·H2On(g)Thermodynamic modeling of the experimental results indicates a preference for specific hydrated species, including NaClg, NaCl·H2O4g, NaCl·H2O6g and NaCl·H2O8g. The less hydrated gaseous NaCl species become more prevalent with increasing temperature and decreasing pressure. At temperatures below 600 °C and pressures above 50 bar, halite solubility is close to stoichiometric, whereas at higher temperatures and lower pressures, the hydrolysis of NaCl(s) to form NaOH(lq,s) or a NaClxOH(1-x)(lq,s) (x < 1) solid solution is evident, resulting in the formation of HCl(g). The logarithm of the halite equilibrium solubility constant (logKn) ranges from −10.18 to −4.19 for NaCl(g), and from −13.12 to −11.94, −15.90 to −17.28, and −19.67 to –22.73 for NaCl·H2O4(g), NaCl·H2O6(g) and NaCl·H2O8(g), respectively. Standard thermodynamic properties derived from this data reveal a temperature-independent enthalpy (ΔHn,ro), entropy (ΔSn,ro) and heat capacity (ΔCp,n,ro) of reaction for each NaCl species. While the enthalpy of reaction is nearly constant, the entropy and heat capacity decrease with an increasing degree of hydration, indicating the decreasing stability of these species with increasing temperature. Our thermodynamic model results and gas species stoichiometries are in excellent agreement with previous density functional theory (DFT) calculations (Suleimenov et al., 2006). The halite solubility data obtained here compare well with prior studies and thermodynamic models for the NaCl-H2O system.

Novel hybrid coating material with triple distinct healing bond for fat oil and grease deposition control in the sewer system

Hybrid materials with distinct self-healing bonds are a prominent category of materials, demanding in various modern applications. Developing self-healable hybrid materials with desired self-healing properties at ambient conditions is highly desirable and challenging. Herein, we developed a novel zinc (II)–dimethylglyoxime–urethane-complex-based polyurethane elastomer (Zn-polyurethane hybrid material) with synergetic triple dynamic bonds, which exhibits spontaneous self-healing properties at 30 °C. Moreover, this material shows excellent thermal stability up to approximately 850 °C and is highly stable in water systems. This hybrid material has potential applications in water systems; in this study, we characterized it for fat, oil and grease (FOG) deposition management in sewer systems by applying it as a coating on concrete blocks. The findings indicate that following a 30-day leaching test conducted under controlled pH conditions on uncoated and Zn-polyurethane-coated concrete blocks, a reduction of over 80 % in calcium release was observed in the coated block compared to the uncoated concrete block. Additionally, in FOG deposit formation tests conducted on uncoated and coated concrete blocks for 30 days, a reduction of over 30 % in FOG deposit formation was noted in the coated sample.

Role of Heat Carrier Components in the Formation of Corrosion and Scale Deposits in the Pipes of Heat Supply Systems

Role of Heat Carrier Components in the Formation of Corrosion and Scale Deposits in the Pipes of Heat Supply Systems

Evaporator Evaluation as a Heat Exchanger in Refrigeration Systems at Constant Thermal Load and Fouling Factor

Heat exchangers are widely used in various industrial installations, one of which is their use in air conditioning systems. In the design process of heat exchangers, the main focus is to determine the dimensions of the device. This is done to determine the performance of the heat exchanger, where the calculation is based on a constant thermal load and a constant fouling factor. When the heat exchanger is first operated, the mass flow rate of the cooling fluid must be lower than the design point to maintain a constant cooling load. However, the conditions for the formation of deposits on the surface of the heat exchanger cannot be known. Therefore, designing a heat exchanger with a constant fouling factor is less realistic.

Tracing fluid signature and metal mobility in complex orogens: insights from Pb-Zn mineralization in the Pyrenean Axial Zone

AbstractOrogenic processes encompass a complex interplay of deformation and metamorphic events, which can impact the formation of ore deposits to various degrees. However, distinguishing fluid signatures from orogenic versus post-orogenic events presents a significant challenge due to the scarcity of robust geochemical indicators that remain unaffected during multiple post-mineral reworking events. This study carefully examines the properties and chemistry of primary and secondary fluid inclusions (FIs), identifying distinct signatures of two fluid populations linked to different styles of Pb-Zn mineralization in the Pyrenean Axial Zone (PAZ) of Southern-France/Northern-Iberia: These included late-Carboniferous stratabound epigenetic Pb-Zn deposits and Mesozoic crosscutting Pb-Zn(-Ge) vein systems. Population (I) is identified in primary and secondary FIs in a few crosscutting Pb-Zn veins and constitutes a minor component in stratabound epigenetic bodies. It exhibits Na-dominated low to intermediate salinity (&lt; 20 wt% NaCl eq.), intermediate temperatures (200–350 °C), abundant CO2-rich FIs and shows low homogeneous Cl/Br molar ratios. These characteristics are consistent with a metamorphic origin of the fluids, associated with Late-Variscan metamorphism. Population (II) is commonly observed in the crosscutting vein systems where it occurs as primary and pseudosecondary FIs, as well as in stratabound epigenetic bodies where it represents the main fluid component of secondary FIs. Population (II) is Ca-dominated with intermediate to high salinity (15–35 wt% NaCl eq.), relatively low temperature (&lt; 200 °C), and shows high Cl/Br molar ratios with significant variations. This last characteristic is typical of mixing of at least two fluids, one with a probable low Cl/Br molar ratio at shallow crustal levels and another with high Cl/Br molar ratio at deeper levels. Characteristics of population (II) are consistent with a fluid of basinal origin that interacted with the basement while circulating in the Pyrenees during the Mesozoic, although a Pyrenean-Alpine age cannot be excluded. Locally, in sphalerite-hosted secondary FIs that form trails in the crosscutting veins, we find evidence of high Ge concentrations (up to few 1000s ppm), which correlate with anomalous Pb and Tl concentrations. Very high metal concentrations (up to 1–2 wt% Pb, Zn), which are inversely proportional to Cl/Br molar ratios, are found in FIs mainly within veins hosted in deep-seated high-grade metamorphic rocks. Based on a compilation of fluid data from the literature, a first-order correlation can be deduced between the metamorphic grade of the rocks hosting the mineralization and the Pb and Zn content in the FIs. Early stratabound orebodies are considered likely sources of metal for the development of the late crosscutting vein mineralization. This study demonstrates the significance and complexity of orogen-scale fluid circulation and supports the importance of pre-existing metal enrichment in the crust, especially in high-grade metamorphic rocks as a prerequisite for the formation of Pb-Zn veins in complex multi-stage orogens.

Revealing Yukon’s hidden treasure: an atomic-scale investigation of Carlin-type gold mineralization in the Nadaleen Trend, Canada

AbstractThe invisible-gold deposits known as Carlin-type are becoming more important as easier to find deposits are progressively depleted. The combination of the invisible nature of the Au in these deposits, as well as the limited surface indicators of these deposits, makes exploration to find new Carlin-type deposits extremely difficult. Comprehensive mineralization models are essential to find new Carlin-type deposits in similar geologic settings. The Nadaleen Trend of Yukon, Canada, is one such district where an improved understanding of this deposit type has led to new discoveries. Previous studies compared and contrasted the tectonic setting, host rock depositional setting, structural preparation, and mineralization style of the Nadaleen Trend with those in Carlin-type localities, Nevada. However, the comparisons at an atomic scale, between Carlin-type Au deposits in the Nadaleen Trend and those in Nevada, has yet to be investigated. This study fills this knowledge gap by combining high resolution microanalytical techniques with atom probe tomography to examine the distribution of Au and other trace elements in the Nadaleen Trend, compare them to a representative Carlin-type deposit in Nevada (Turquoise Ridge), and determine how widespread the mineralization model is. Our findings show that in the Nadaleen Trend, as in Nevada, Au is generally directly linked with As at the macro to atomic scale, and is incorporated into As/Au rich overgrowths on sedimentary/diagenetic pyrite. Gold-rich pyrite rims in the Nadaleen Trend are generally smaller than those found in Nevada (0.5–2 µm vs &gt; 10 µm), although the ore grades appear comparable. We find that the Au in the pyrite of the Nadaleen Trend is homogenously distributed (i.e. lattice bound) at the atomic scale, but that there is a notable enrichment of As surrounding individual Au atoms. These findings are in agreement with those from previous work on a representative deposit in Nevada, and support the assertation that As is the key ingredient in facilitating the incorporation of Au into the pyrite lattice. Arsenic as an essential component in the trapping mechanisms of Au in CTG deposits, is something that has been as to yet underappreciated in the current models of CTG deposit formation.

Experimental study of vegetable oil droplets vaporization under low temperature conditions such as those found in diesel engine cold parts

This paper presents an analysis of three vegetable oil droplets vaporization process in the range temperature from 473 to 723 K corresponding to low temperature conditions found in diesel engine cold parts. This process is analyzed for a droplet evaporating in a hot environment at atmospheric pressure using the fiber-suspended droplet technique well used in the literature, and analyzing the droplet normalized square diameter and temperature evolution surrounding the droplet when vaporizing. The main difference between those already studied in literature is the range temperature which varies between 473 and 723 K in which vegetable oils vaporizing problems leading to deposits formation in the cold regions of diesel engines especially in direct injection. This presents a scientific challenge for resolving deposit formation. The findings reveal that vegetable oil droplets experience expansion and heating for temperatures below 623 K: no other changes are observed. Between temperatures of 623 and 683 K, an increase in temperature, expansion, and an inconsistent vaporization is observed. This is followed by a phase of low and constant vaporization. From 683 K, vegetable oils experience an initial stage of heating and expansion, which is accompanied by a phenomenon of puffing and bursting. Finally, in the last phase, residue formation occurs. Puffing and bursting phenomena manifest once the temperature reaches 683 K, indicating the emergence of substantial quantities of light compounds including carboxylic acids, aromatics, acrolein, ketene, and fatty acids. These compounds are formed through the thermal degradation and polymerization of vegetable oils. This process causes deposits to form in the colder areas of diesel engines.

Genesis of the Qingchayuan Flake Graphite Deposit in the Huangling Dome of Yangtze Block, South China

The Qingchayuan flake graphite deposit is located in the Huangling Dome, which represents a part of the Yangtze Block in South China. This deposit is a major and highly typical flake graphite deposit within this metallogenic region. The graphite ores are found within graphite-bearing mica schist and graphite-bearing biotite–plagioclase gneiss. The fixed carbon content varies from 3.52 to 13.78% with an average of 7.83%. The major element analysis shows that the main chemical components of the Qingchayuan flake graphite ore are SiO2, Al2O3, TFe2O3, and K2O. The carbon isotope study of the graphite ore indicates light carbon values ranging from −22.80 to −26.72‰, suggesting that it has a biogenic origin. In addition, the sulfur isotope values of the graphite samples range from −10.67 to −14.58‰, indicating the formation of the graphite deposit is related to biological processes. The presence of traces of migmatization around the graphite deposit indicates that the graphite has undergone ultra-high temperatures during the formation process. The origin of the Qingchayuan flake graphite deposit is explained by a two-stage genetic model, which involves material deposition and regional metamorphism (including migmatization). Firstly, after the deposition of carbonaceous material and its conversion into graphite by regional metamorphism, the graphite might have undergone recrystallization, resulting in the development of big flakes due to migmatization. This model is supported by previous studies and newly collected information.

Comparative determination of the time-dependent accumulation of metal oxides in the landfill gas combustion chamber deposits using SEM-EDS, XRF and ICP OES

Non-purified landfill gas (LFG) leads to the formation of complex deposits in combustion chambers due to impurities such as siloxanes, sulfur compounds, and organometallic compounds containing elements such as Si, S, Sb, Sn. This study focused on identifying the elemental composition of deposits from four combustion chambers using analytical techniques including SEM-EDS, WDXRF, and microwave digestion ICP OES. The dominant element, Si, with concentrations (wt%) in the deposits was measured by SEM-EDS, ICP-OES, and WDXRF, respectively, as follows: 17.04 ± 8.59, 21.89 ± 4.39, and 16.63 ± 0.94 for cylinder head deposits, and 13.28 ± 6.97, 15.40 ± 5.40, and 12.64 ± 1.64 for piston head deposits. Excluding C, O and N, which could not be analyzed by all three techniques, the multi-analytical approaches demonstrated strong correlations between EDS results and those obtained from WDXRF and ICP OES, with R2 values of 0.9173 and 0.9002 for cylinder head deposits, respectively. It was also revealed that the elemental composition of deposits varied between combustion chambers. The average mass fractions of all deposit surfaces were ranked as follows for elements exceeding 1 %: O (45.38 %) > Si (16.67 %) > Ca (9.87 %) > Sb (7.21 %) > S (5.98 %) > Sn (3.51 %) > C (2.83 %) > P (2.35 %). Elements below 1 % were ranked as: Na (0.91 %) > N (0.80 %) > Al (0.74 %) > Fe (0.48 %) > Mg (0.30 %). Consequently, the multi-spectrometry analysis approach provides a more comprehensive understanding of the deposit composition, enabling the determination of primary contributors and the most elements. Future studies may involve more general determining the concentrations of organometallic compounds in the LFG, which are the source of the elements found in the deposit.

Integrative analysis of gene expression, protein abundance, and metabolomic profiling elucidates complex relationships in chronic hyperglycemia-induced changes in human aortic smooth muscle cells

Type 2 diabetes mellitus (T2DM) is a major public health concern with significant cardiovascular complications (CVD). Despite extensive epidemiological data, the molecular mechanisms relating hyperglycemia to CVD remain incompletely understood. We here investigated the impact of chronic hyperglycemia on human aortic smooth muscle cells (HASMCs) cultured under varying glucose conditions in vitro, mimicking normal (5 mmol/L), pre-diabetic (10 mmol/L), and diabetic (20 mmol/L) conditions, respectively. Normal HASMC cultures served as baseline controls, and patient-derived T2DM-SMCs served as disease controls. Results showed significant increases in cellular proliferation, area, perimeter, and F-actin expression with increasing glucose concentration (p < 0.01), albeit not exceeding the levels in T2DM cells. Atomic force microscopy analysis revealed significant decreases in Young’s moduli, membrane tether forces, membrane tension, and surface adhesion in SMCs at higher glucose levels (p < 0.001), with T2DM-SMCs being the lowest among all the cases (p < 0.001). T2DM-SMCs exhibited elevated levels of selected pro-inflammatory markers (e.g., ILs-6, 8, 23; MCP-1; M-CSF; MMPs-1, 2, 3) compared to glucose-treated SMCs (p < 0.01). Conversely, growth factors (e.g., VEGF-A, PDGF-AA, TGF-β1) were higher in SMCs exposed to high glucose levels but lower in T2DM-SMCs (p < 0.01). Pathway enrichment analysis showed significant increases in the expression of inflammatory cytokine-associated pathways, especially involving IL-10, IL-4 and IL-13 signaling in genes that are up-regulated by elevated glucose levels. Differentially regulated gene analysis showed that compared to SMCs receiving normal glucose, 513 genes were upregulated and 590 genes were downregulated in T2DM-SMCs; fewer genes were differentially expressed in SMCs receiving higher glucose levels. Finally, the altered levels in genes involved in ECM organization, elastic fiber synthesis and formation, laminin interactions, and ECM proteoglycans were identified. Growing literature suggests that phenotypic switching in SMCs lead to arterial wall remodeling (e.g., change in stiffness, calcific deposits formation), with direct implications in the onset of CVD complications. Our results suggest that chronic hyperglycemia is one such factor that leads to morphological, biomechanical, and functional alterations in vascular SMCs, potentially contributing to the pathogenesis of T2DM-associated arterial remodeling. The observed differences in gene expression patterns between in vitro hyperglycemic models and patient-derived T2DM-SMCs highlight the complexity of T2DM pathophysiology and underline the need for further studies.