Formation Of Deposits Research Articles

New insights on the formation of the polymetamorphic Felbertal tungsten deposit (Austria, Eastern Alps) revealed by CL, EPMA, and LA-ICP-MS investigation

AbstractThe Felbertal tungsten deposit is the only economic scheelite mine in Europe, yet its genesis is not fully understood. It has been argued recently that the formation of the deposit is most likely related to granitic intrusions of Variscan age, contrasting a previously suggested syn-depositional stratabound origin of Early Cambrian age. Solving this controversy remains challenging due to the polymetamorphic evolution of the deposit, which experienced both Variscan and Alpine metamorphism. In this contribution we present a comprehensive new data set of scheelite major, minor, and trace element concentrations from multiple scheelite generations of the Felbertal deposit along with microstructural observations. Our results show that Mo, Mo/Mn, REE, Y/Ho, Nb, and Nb/Ta in scheelite are variable within the different scheelite generations and are predominantly controlled by the host-rock lithologies on the local scale, whereas in general the data show a strong response to the shift of P, T, and pH upon changing magmatic-hydrothermal to metamorphic conditions. For the first time, we identify remnants of primary scheelite in the Western Ore Zone. The presented data support a magmatic-hydrothermal origin of the first scheelite mineralization during the Variscan orogeny with primary scheelite being characterized by wing-shaped REE patterns with a negative Eu-anomaly, high trace element concentrations, non-chondritic Y/Ho, and high Nb/Ta. Primary scheelite underwent metamorphic/hydrothermal alteration (recrystallization and dissolution-reprecipitation processes) during the Variscan and Alpine orogeny. This case study highlights that indicative mineralization-controlling geochemical ratios like Sr/Mn cannot be applied for polymetamorphic tungsten deposits like Felbertal.

The Chain of Processes Forming Porphyry Copper Deposits—An Invited Paper

Abstract Porphyry-related mineral deposits are giant geochemical anomalies in the Earth’s crust with orders-of-magnitude differences in the content and proportion of the three main ore metals Cu, Au, and Mo. Deposit formation a few kilometers below surface is the product of a chain of geologic processes operating at different scales in space and time. This paper explores each process in this chain with regard to optimizing the chances of forming these rare anomalies. On the lithosphere scale, deposits with distinct metal ratios occur in provinces that formed during brief times of change in plate motions. Similar metal ratios of several deposits in such provinces compared with global rock reservoirs suggest preceding enrichment of Au or Mo in lithospheric regions giving rise to distinct ore provinces. The largest Cu-dominated deposits and provinces are traditionally explained by selective removal of Au during generation or subsequent evolution of mantle magmas, but the possibility of selective Cu pre-enrichment of lithosphere regions by long-term subduction cannot be dismissed, even though its mechanism remains speculative. Evolution of hydrous basaltic melts to fertile magmas forming porphyry Cu deposits requires fractionation toward more H2O-rich magmas in the lower crust, as shown by their adakite-like trace element composition. The prevailing interpretation that this fractionation leads to significant loss of chalcophile ore metals by saturation and removal of magmatic sulfide might be inverted to a metal enrichment step, if the saturating sulfides are physically entrained with the melt fraction of rapidly ascending magmas. Ascent of fertile magma delivers a large mass of H2O-rich ore fluid to the upper crust, along points of weakness in an overall compressive stress regime, within a limited duration as required by mass and heat balance constraints. Two mechanisms of rapid magma ascent are in debate: (1) wholesale emplacement of highly fractionated and volatile-rich granitic melt into a massive transcrustal channelway, from which fluids are exsolved by decompression starting in the lower crust, or (2) partly fractionated magmas filling a large upper crustal magma chamber, from which fluids are expelled by cooling and crystallization. Transfer of ore-forming components to a hydrothermal ore fluid is optimized if the first saturating fluid is dense and Cl rich. This can be achieved by fluid saturation at high pressure, or after a moderately H2O rich intermediate-composition melt further crystallizes in an upper crustal reservoir before reaching fluid saturation. In either case, metals and S (needed for later hydrothermal sulfide precipitation) are transferred to the fluid together, no matter whether ore components are extracted from the silicate melt or liberated to the ore fluid by decomposition of magmatic sulfides. Production and physical focusing of fluids in a crystallizing upper crustal magma chamber are controlled by the rate of heat loss to surrounding rocks. Fluid focusing, requiring large-scale lateral flow, spontaneously occurs in mushy magma because high water content and intermediate melt/crystal ratio support a network of interconnected tubes at the scale of mineral grains. Calculated cooling times of such fluid-producing magma reservoirs agree with the duration of hydrothermal ore formation measured by high-precision zircon geochronology, and both relate to the size of ore deposits. Ore mineral precipitation requires controlled flow of S- and metal-rich fluids through a vein network, as shown by fluid inclusion studies. The degree of hydrothermal metal enrichment is optimized by the balance between fluid advection and the efficiency of cooling of the magmatic fluid plume by heat loss to convecting meteoric water. The depth of fluid production below surface controls the pressure-temperature (P-T) evolution along the upflow path of magmatic fluids. Different evolution paths controlling density, salinity, and phase state of fluids contribute to selective metal precipitation: porphyry Au deposits can form at shallow subvolcanic levels from extremely saline brine or salt melt; high-grade Au-Cu coprecipitation from coexisting and possibly rehomogenizing brine and vapor is most efficient at a depth of a few kilometers; whereas fluids cooling at greater depth tend to precipitate Cu ± Mo but transport Au selectively to shallower epithermal levels. Exhumation and secondary oxidation and enrichment by groundwater finally determine the economics of a deposit, as well as the global potential of undiscovered metal resources available for future mining.

Investigation of mechanical properties, remineralization, antibacterial effect, and cellular toxicity of composite orthodontic adhesive combined with silver-containing nanostructured bioactive glass

BackgroundThe formation of white spots, which represent early carious lesions, is a major issue with fixed orthodontics. The addition of remineralizing agents to orthodontic adhesives may prevent the formation of white spots. The aim of this study was to produce a composite orthodontic adhesive combined with nano-bioactive glass-silver (nBG@Ag) for bracket bonding to enamel and to investigate its cytotoxicity, antimicrobial activity, remineralization capability, and bond strength.MethodsnBG@Ag was synthesized using the sol-gel method, and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy with an attenuated total reflectance attachment (ATR-FTIR). The cytotoxicity test (MTT) and antimicrobial activity of adhesives containing 1%, 3%, and 5% (wt/wt) nBG@Ag were evaluated, and the shear bond strength of the adhesives was measured using a universal testing machine. Remineralization was assessed through microhardness testing with a Vickers microhardness tester and scanning electron microscopy (SEM). Statistical analyses were conducted using the Shapiro-Wilk test, Levene test, one-way ANOVA, Robust-Welch test, Tukey HSD method, and two-way ANOVA.ResultsThe biocompatibility of the adhesives was found to be high, as confirmed by the lack of significant differences in the cytotoxicity between the sample and control groups. Discs made from composites containing nBG@Ag exhibited a significant reduction in the growth of Streptococcus mutans (p < 0.05), and the antibacterial activity increased with higher percentages of nBG@Ag. The shear bond strength of the adhesives decreased significantly (p < 0.001) after the addition of nanoparticles, but it remained above the recommended value. The addition of nBG@Ag showed improvement in the microhardness of the teeth, although the differences in microhardness between the study groups were not statistically significant. The formation of hydroxyapatite deposits on the tooth surface was confirmed through SEM and energy-dispersive X-ray spectroscopy (EDX).ConclusionAdding nBG@Ag to orthodontic adhesives can be an effective approach to enhance antimicrobial activity and reduce enamel demineralization around the orthodontic brackets, without compromising biocompatibility and bond strength.

Lithium occurrences and enrichment of granite regolith-hosted Li deposits in Jiangxi Province, South China: An example of the Xikeng Li deposit

The muscovite granite regolith in Jiangxi Province, with thickness up to 30 m, exhibits significant lithium (Li) enrichment, which holds promising potential as an economically viable alternative source of Li. However, host minerals and enrichment mechanism of Li in such regolith are poorly understood. Herein, mineralogy and geochemistry of the Xikeng granite-hosted regolith Li deposit were investigated. The studied regolith has Li2O grade up to 1.0 wt%, which showcases an approximately twofold increase in Li content compared to that found in the bedrock. Enrichment of Li in the parent granite facilitates the formation of granite regolith-hostedLi deposits. The dominant minerals observed in the studied weathering profile are derived from the parent granite through inheritance and/or transformation. The incipient stage of weathering is characterized by dissolution of K-feldspar and plagioclase and accumulation of quartz and muscovite, whereas the subsequent stage of weathering is characterized by the development of clay minerals, particularly kaolinite. The predominant reservoir for Li in the regolith is proposed to be the residual muscovite, as suggested by positive correlation between Li concentrations and muscovite content, a dominance of over 90 % in the residual phase compared to other phases from the extraction experiment, and element mapping. Adsorption of kaolinite formed through the weathering of muscovite is insufficient to effectively retain released Li, resulting in its loss with fluids. The deficiency of Li enrichment in the upper part of regolith can be attributed to this factor. The central part of regolith exhibits the most important enrichment, characterized by absence of feldspars, presence of minor clay minerals, and massive gathering of muscovite without obviously chemical weathering. This study provides confirmation that granite regolith represents a commercially viable Li resource.

Direct prediction of isotopic properties from molecular dynamics trajectories: Application to sulfide, sulfate and sulfur radical ions in hydrothermal fluids

In hydrothermal fluids, disulfur (S2•−) and trisulfur (S3•−) radical anions have been observed to coexist with the major hydrogen sulfide and sulfate species. These radical ions have potentially important effects on the solubility, transport and fractionation of metals and sulfur, with consequences for ore deposit formation and, more generally, for geochemical cycles of metals and volatiles. It is therefore essential to know the intrinsic isotopic properties of these important sulfur species in order to use sulfur isotopes for tracing different geological processes. Here, the theoretical equilibrium isotopic properties of the disulfur and trisulfur radical ions are computed and compared to the hydrogen sulfide (H2S) and sulfate ion (SO42−), using, for the first time, a first-principles molecular dynamics (MD) approach. The isotopic properties are calculated directly from molecular dynamics trajectories using the vibrational density of states and the atomic kinetic energy, and then compared to the more established method based on sampling of several snapshots. This comparison allowed us to validate the new modelling method and to assess its advantages and limitations. The predicted equilibrium isotope fractionation in terms of 34S/32S between S2•− and S3•− is small, i.e. <1‰, with a slight enrichment in the heavier isotope for S3•−, over the temperature range 200–500 °C. Both radical ions are slightly depleted in the heavier isotope, by 1 to 2‰, relative to aqueous H2S. Our results help tuning sulfur isotope fractionation models used for tracing the origin and evolution of hydrothermal fluids. Our method opens large perspectives for using the rapidly growing body of MD simulation data in geosciences on structure and stability of aqueous complexes to assess in parallel element isotope fractionations from MD-generated trajectories.

Correlation Analysis Between Tumor Deposit and Clinicopathologic Characteristics and Prognosis of Gastric Cancer: A Multicenter Retrospective Study.

The mechanism underlying the formation of gastric tumor deposits (TDs) is unclear. We aimed to explore the risk factors for the formation and prognostic value of TDs. This retrospective analysis included 781 locally advanced gastric cancer (LAGC) patients from four medical institutions in China, from June 2014 to June 2018. The risk factors for TD formation and prognostic value were determined through univariate and multivariate analyses. Univariate analysis revealed that TD positivity was closely related to tumor diameter, Borrmann classification, differentiation degree, pT stage, pN stage, pTNM stage, and nerve and vascular invasion (p < 0.05). Multivariate logistic regression revealed that tumor diameter ≥ 5cm (odds ratio [OR] 1.836, 95% confidence interval [CI] 1.165-2.894, p = 0.009) and vascular invasion (OR 2.152, 95% CI 1.349-3.433, p = 0.001) were independent risk factors for TD positivity. Multivariate Cox analysis revealed that TD positivity (OR 1.533, 95% CI 1.101-2.134, p = 0.011), tumor diameter ≥ 5 cm (OR 1.831, 95% CI 1.319-2.541, p<0.001), pT4a stage (OR 1.652, 95% CI 1.144-2.386, p = 0.007), and vascular invasion (OR 1.458, 95% CI 1.059-2.008, p = 0.021) were independent risk factors for GC prognosis. The 5-year overall and disease-free survival of the TD-positive group showed significant effects among patients in the pT4a and pN3b stages (p < 0.05). TDs are closely related to tumor diameter and vascular invasion in LAGC patients, and TD positivity is an independent prognostic factor for LAGC patients, especially those at pT4a and pN3b stages.

Hydrogen Production by Steam Reforming of Ethanol and Dry Reforming of Methane with CO2 on Ni/Vermiculite: Stability Improvement via Acid or Base Treatment of the Support.

In this study, vermiculite was explored as a support material for nickel catalysts in two key processes in syngas production: dry reforming of methane with CO2 and steam reforming of ethanol. The vermiculite underwent acid or base treatment, followed by the preparation of Ni catalysts through incipient wetness impregnation. Characterization was conducted using various techniques, including X-ray diffraction (XRD), SEM-EDS, FTIR, and temperature-programmed reduction (H2-TPR). TG-TD analyses were performed to assess the formation of carbon deposits on spent catalysts. The Ni-based catalysts were used in reaction tests without a reduction pre-treatment. Initially, raw vermiculite-supported nickel showed limited catalytic activity in the dry reforming of methane. After acid (Ni/VTA) or base (Ni/VTB) treatment, vermiculite proved to be an effective support for nickel catalysts that displayed outstanding performance, achieving high methane conversion and hydrogen yield. The acidic treatment improved the reduction of nickel species and reduced carbon deposition, outperforming the Ni over alkali treated support. The prepared catalysts were also evaluated in ethanol steam reforming under various conditions including temperature, water/ethanol ratio, and space velocity, with acid-treated catalysts confirming the best performance.

Arsenic-poor fluids promote strong As partitioning into pyrite

Pyrite is a ubiquitous sulfide mineral found in diverse geological settings and holds great significance in the formation of Au deposits as well as the safe utilization of groundwater due to its remarkable ability to incorporate substantial amounts of As. However, despite its importance, there remains a dearth of fundamental data on the partitioning of As between pyrite and fluid, which is key for accurately modeling the As distribution in these environments.Here, we present new insights into the partitioning behavior of As between pyrite and fluid at conditions that mimic natural fluid systems. Pyrite was synthesized by replacement of natural siderite in hydrothermal experiments at 200 °C and pH 5 applying a wide range of fluid As concentrations, spanning from 0.001 to 100 µg/g. The As distribution and concentration in synthetic pyrite was analyzed by quantitative LA-ICP-MS mapping providing a high spatial resolution and sensitivity at 2–3 µm image pixel size at a detection limit of ∼1 µg/g at the single pixel scale. Pyrite-fluid partitioning coefficients (DAs(py/fluid)) between synthetic pyrite and experimental fluid agree with previously published data for high fluid As concentrations of 1 µg/g to 100 µg/g (DAs < 2000). However, at low As concentrations in the experimental fluid (<1 µg/g), a steep increase in the DAs(py/fluid) values of up to ∼30,000 was detected, demonstrating even stronger As partitioning into pyrite. This is confirmed by the analyses of natural pyrite that precipitated from As-poor fluids (0.3–0.4 ng/g) within a deep anoxic aquifer in SE Sweden. The discovery holds significant implications for the mobility and scavenging of As, which in turn is important for understanding the formation and fingerprinting of mineral deposits as well as for the secure utilization of groundwater resources.

Deciphering sources of lode gold deposits in the South Tianshan, NW China: Insights from Pb isotope systematics

The Tianshan hosts numerous giant and world-class lode gold deposits, forming one of the world’s largest gold provinces. However, the sources of gold remain equivocal. Herein, we present a comprehensive Pb isotopic investigation of the Precambrian basement, Neoproterozoic mafic dykes, and the Lower Paleozoic sequences of the South Tianshan in NW China. These data were compared with existing Pb isotope datasets from major lode gold deposits and coeval granitoid and mantle-related rocks, to trace the sources of gold and constrain the relative contributions from potential reservoirs. Gold-bearing sulfides from major lode gold deposits have relatively uniform Pb isotopic ratios, which are significantly different from regional coeval granitoid and mantle-related rocks. Conversely, the Pb isotopic characteristics from gold-bearing sulfides are comparable to those from the Paleoproterozoic metasedimentary rocks, showing well-defined linear relations. Binary mixing modeling shows that the Paleoproterozoic metasedimentary rocks might have contributed 70% to 90% for the source of Pb and, by inference other metals. Integrating geochemical and isotopic features from major lode gold deposits in the region, we propose that it invokes fertilization of ancient Au archives during metamorphic volatilization in the deep crust during subduction of the South Tianshan Ocean. Following the final closure of the South Tianshan Ocean, the regional tectonic uplift and thermal effect during widespread granitoids emplacement associated with the amalgamation of the Tarim with Kazakhstan-Yili terranes, mobilizing the deep roots of the fertilized ancient Au reservoirs, leading to the formation of the gold deposit hosted in fault systems of the South Tianshan.

Impact of Resolvin-E1 and Maresin-1 on Bone Marrow Stem Cell Osteogenesis under Inflammatory Stress.

Periodontal disease is characterized by inflammation and bone loss. Central to its pathogenesis is the dysregulated inflammatory response, complicating regenerative therapies. Mesenchymal stem cells (MSCs) hold significant promise in tissue repair and regeneration. This study investigated the effects of specialized pro-resolving mediators (SPMs), Resolvin E1 (RvE1) and Maresin 1 (MaR1), on the osteogenic differentiation of human bone marrow-derived MSCs under inflammatory conditions. The stem cells were treated with SPMs in the presence of lipopolysaccharide (LPS) to simulate an inflammatory environment. Osteogenic differentiation was assessed through alkaline phosphatase activity and alizarin red staining. Proteomic analysis was conducted to characterize the protein expression profile changes, focusing on proteins related to osteogenesis and osteoclastogenesis. Treatment with RvE1 and MaR1, both individually and in combination, significantly enhanced calcified deposit formation. Proteomic analysis revealed the differential expression of proteins associated with osteogenesis and osteoclastogenesis, highlighting the modulatory impact of SPMs on bone metabolism. RvE1 and MaR1 promote osteogenic differentiation of hBMMSCs in an inflammatory environment, with their combined application yielding synergistic effects. This study provides insights into the therapeutic potential of SPMs in enhancing bone regeneration, suggesting a promising avenue for developing regenerative therapies for periodontal disease and other conditions characterized by inflammation-induced bone loss.

Construction of an extraordinary stable mesoporous carbocatalyst in acetylene hydrochlorination via boric acid assistance

In recent years, metal-free carbon catalysts have garnered significant attention as substitutes for metal catalysts due to their cost-effectiveness and increased resistance to poisoning. However, the stability of metal-free carbon catalysts still lags behind that of metal catalysts, presenting a significant hurdle to industrialization. To enhance the catalytic stability of these catalysts, a boron-nitrogen co-doped mesoporous carbon (B, N-MC) catalyst was synthesized using polyacrylonitrile (PAN) as the carbon and nitrogen source, with boric acid serving as the electron regulator. The acetylene conversion on the B, N-MC(0.5) catalyst reached 62.8 % at 220 °C and gas hourly space velocity (GHSV) of C2H2 at 300 h−1, even high than 0.25%Au/AC catalyst (53.3 %). Importantly, the B, N-MC(0.5) catalyst exhibited excellent stability, maintaining its initial activity even after 500 h of evaluation. Experimental and theoretical analyses demonstrate that the B–N pairs, facilitated by the electronic regulation ability of boric acid, effectively inhibits the polymerization of acetylene molecules, mitigates the formation of carbon deposits, thereby enhancing the stability of the catalyst.

Characterizing sulfur redox state and geochemical implications in deep-time using mineral chemistry network analysis

Sulfur (S) is a central element in global biogeochemical cycling and Earth’s redox evolution. Minerals that contain S are an important record of local environmental conditions at the time of their formation based on chemical speciation and redox. However, the oxidation state of S for hundreds of different S-containing minerals and thousands of S-containing mineral localities is unknown, largely sulfides and sulfosalts, and the redox state alone does not fully capture mineral chemistry diversity, thus limiting understanding of S redox evolution. Here, we use mineral chemistry network analysis and the weighted Mineral Element Electronegativity Coefficient of Variation (wMEECV) metric to investigate the element interactions and localities of S-containing minerals from the Mineral Evolution Database (MED) to infer the redox state of S in minerals where the redox state is unknown (SU). Louvain community detection of the S mineral chemistry redox network reveals that there are three main network communities that are separated by redox state. The S6+ community includes minerals that contain the S6+ redox state and a small number of S4+ and S2+ minerals, the S2− community includes S2−-containing minerals, and the SU community includes minerals in which the redox state of S is unknown. The wMEECV values of the SU community closely overlap with the wMEECV values of the S2− community, and do not overlap with the wMEECV values of the S6+ community, indicating the SU community minerals contain predominately reduced S. Assuming that SU community minerals contain reduced S, as supported by their network chemical associations and wMEECV values, then reduced S-containing minerals make up approximately 81 % of S-containing mineral localities in the S mineral chemistry network, even though the majority of all mineral localities (S-containing and non-S-containing) are oxygen (O)-containing minerals. Additionally, reduced S-containing minerals make up the majority (∼75 %) of all non-O containing mineral localities in the MED, representing the importance of reduced S as an electron source and substrate in the evolution of microbial metabolic networks. The range wMEECV values of S6+ community minerals expands through time due primarily to formation of chemically diverse sulfate minerals, coinciding with crustal oxidation from the late Proterozoic to Phanerozoic and the expansion of the marine sulfate reservoir. The intersection of shared constituent elements among reduced and oxidized S in the mineral chemistry network represents redox convergence of weathered S in the geosphere that was crucial in the formation of natural resource deposits and the evolution of biogeochemical cycles.

A Predictive Model for Wellbore Temperature in High-Sulfur Gas Wells Incorporating Sulfur Deposition

HSG (high-sulfur gas) reservoirs are prevalent globally, yet their exploitation is hindered by elevated levels of hydrogen sulfide. A decrease in temperature and pressure may result in the formation of sulfur deposits, thereby exerting a notable influence on gas production. Test instruments are susceptible to significant corrosion due to the presence of hydrogen sulfide, resulting in challenges in obtaining bottom hole temperature and pressure test data. Consequently, a WTD (wellbore temperature distribution) model incorporating sulfur precipitation was developed based on PPP (physical property parameter), heat transfer, and GSTP (gas–solid two-phase) flow models. The comparison of a 2.53% temperature error and a 4.80% pressure error with actual field test data indicates that the established model exhibits high accuracy. An analysis is conducted on the impact of various factors, such as production, sulfur layer thickness, reservoir temperature, and reservoir pressure, on the distribution of the wellbore temperature field and pressure field. Increased gas production leads to higher wellhead temperatures. The presence of sulfur deposits reduces the flow area and wellhead pressure. A 40% concentration of hydrogen sulfide results in a 2 MPa pressure drop compared to a 20% concentration. Decreased reservoir pressure and temperature facilitate the formation of sulfur deposits at the wellhead.

Lithospheric influence on metallogenesis in the East Kunlun Orogen: Insights from isotopic and geochemical mapping

This study examines the influence of lithospheric architecture on regional metallogenesis, using geological and geochemical data from the East Kunlun Orogen (EKO). We explore how specific lithospheric components and structures affect the formation of orogenic gold and various polymetallic mineral deposits. The study reveals that metallogenic processes in the EKO initially targeted sources within the metasomatized-enriched subcontinental lithospheric mantle (SCLM) and reactivated lower crust during the Paleozoic era.Lithospheric architecture, shaped by crust-mantle interactions occurred in the Early Mesozoic led to variations in the sizes of orogenic gold deposits between the eastern and western EKO. In the west, smaller gold deposits are linked to moderate mantle underplating and slightly enriched SCLM. Gold-bearing fluids released by mantle devolatilization mixed with metamorphism fluid in collision stage, contributing to the formation of these deposits. In contrast, the eastern EKO hosts larger gold deposits, resulting from significantly enriched SCLM. Extensive lithospheric thinning process in post-collision stage lead to the mixing of gold-bearing mantle-derived and magmatic-hydrothermal fluids. Fertilized magma differentiation potentially increases gold concentrations in this region.Additionally, Triassic-era melting of the lower crust led to diverse mineralization types in porphyry-skarn-epithermal deposit systems. Key findings include the role of juvenile fertile lower crustal materials in forming copper polymetallic deposits, the importance of metamorphic basement reworking for molybdenum and tungsten deposits, and the influence of lead and zinc leaching from old sedimentary rocks on the formation of silver‑lead‑zinc deposits. This study broadens our understanding of the geological factors influencing metallogenesis and provides a framework for future exploration and research in regions with similar lithospheric architectures.

Role of chalcophile element fertility in the formation of the eastern Tethyan post-collisional porphyry Cu deposits

Role of chalcophile element fertility in the formation of the eastern Tethyan post-collisional porphyry Cu deposits

The role of protolith composition in the formation of tin-enriched granitic melts: A modeling study using the example of the southwest China tin province

Important features of Sn mineralization are the heterogeneous geographic distribution and frequent regional separation from W mineralization in spite some similarities of Sn and W behavior during magmatic processes. Major Sn and W mineralization is often spatially associated with peraluminous granites, which are derived from partial melting of metasediments. Several concepts have been suggested to explain those features, such as a weathering-related Sn-enriched source, Sn redistribution between melts and restite during protolith melting, and extensive fractional crystallization. We demonstrate the importance of protolith composition for the formation of Sn (and W) granites by using a comprehensive bulk-rock composition dataset from Precambrian metasediments of the South China Sn-W province and employing a thermodynamic modeling approach. We used four compositional proxies for phase equilibria calculations, which are the metasediments of the Mengdong, Sibao, Pingbian, and Shuangqiaoshan Groups. It is well documented that those Precambrian metasediments are important protoliths of Sn granites in South China. We present quantitative evaluation of the control of protolith composition in the generation of Sn-enriched granitic melts using South China as example, but our conclusions may also be applicable to worldwide Sn–enriched granites. Our results indicate that the protolith major-element geochemistry controls the anatectic reactions and melt productivity at specific melting conditions, and consequently the partitioning behavior of Sn. Further, pre-enrichment of Sn is crucial to the fertility of granitic melt and may be a prerequisite, particularly for the formation of giant Sn deposits. We propose that the heterogeneous distribution of favorable source rocks is one of the important factors that control the spatial distribution of major Sn (and W) districts in South China and other regions worldwide.

Calculation of the required methanol consumption during the flow of wet hydrocarbon gas in a horizontal pipeline

One of the main problems that have to be solved during the development of hydrocarbon deposits is the formation of gas hydrates in pipelines. In this regard, the article presents a preventive method to struggle against the formation of gas hydrate deposits on the pipes inner walls associated with the supply of a hydrate formation inhibitor to the gas stream. The research was conducted on the basis of a mathematical model of the wet hydrocarbon gas flow in a horizontal pipeline. The research object is to determine the minimum required consumption of methanol, in which there is no formation of gas hydrate deposits on the channel inner walls. The practical significance of this study is that it is aimed at reducing the risks associated with the formation of gas hydrates in pipelines. The numerical implementation of a mathematical model of natural gas flow in a horizontal channel is based on a sequential solution of a system of four differential equations by the Runge-Kutta method of 4 orders of accuracy, followed by a search for sequential approximations of the minimum inhibitor flow rate, in which the "gas + water ↔ gas hydrate phase" transition process does not occur on the inner surface of the channel. The article presents a calculation of the proportion of a hydrate formation inhibitor in the liquid phase by solving a cubic equation using the Cardano method. Based on the computational experiments results, graphs were constructed and interpreted of the dependencies of the minimum inhibitor consumption on the soil temperature, inlet gas pressure, total water concentration in the gas flow, initial gas temperature and total gas flow rate.

The Trans-Crustal Evolution of Miocene Magmatism Parental to Epithermal Mineralization in the Sierra Madre del Sur, Southern Mexico

Abstract Arc-related volcanism results from the interplay of magmatic processes occurring in trans-crustal systems that consolidate over time in a given location. Trans-crustal systems comprise extensive networks of magma reservoirs and conduits at different depths, wherein melts cyclically differentiate and segregate before reaching the surface. The study of these systems provides valuable insights into crustal-scale phenomena, such as the evolution of the continental crust and the formation of metallogenic regions. In this study, we address the trans-crustal magmatic evolution of lower Miocene magmatism parental to several intermediate-sulfidation epithermal deposits in the eastern Sierra Madre del Sur igneous province, southern Mexico. Using a multi-methodological approach, we document changes over ca. 1.1 Myr in the magmatic system that fed andesitic-to-felsic volcanism in this region. We employ whole-rock REE ratios and λ parameters—which are used to quantify the shape of a REE pattern—to track the involvement of pressure-sensitive minerals in the deep-crustal magmatic evolution. The andesitic rocks consist of lava flows, porphyries, and dikes that collectively show REE patterns suggestive of control by fractionated or residual (i.e. in crustal melting) amphibole and/or clinopyroxene. In contrast, the felsic rocks consist of rhyolitic–dacitic ignimbrites, domes, and dikes that show contrasting REE patterns suggestive of control by plagioclase, clinopyroxene, amphibole, and/or garnet. The distinct pressure-sensitive mineral assemblages in the andesitic and felsic rocks indicate that the locus of deep-crustal magma evolution varied within the middle–lower crust. These magmas were episodically injected into ephemeral shallow crustal reservoirs (shortly?) before being erupted, inducing a progressive thermomechanical maturation of the middle–upper crust. Meanwhile, low degrees of crustal assimilation occurred as recorded by Mesozoic inherited zircon ages and Sr–Nd–Pb radiogenic isotopes. An extensive middle–lower crustal magma evolution has been linked to the formation of porphyry Cu deposits (i.e. ‘fertile’ magmatism). Given that intermediate-sulfidation epithermal deposits may be genetically linked with porphyry Cu deposits, the documented processes could have contributed to the formation of epithermal deposits in the region. However, magmatic fertility proxies resemble those from infertile magmas worldwide. Since these proxies have been exclusively applied to porphyry-type deposits, our results highlight the importance of developing new geochemical exploration tools applicable to a wider range of ore deposits.

Fault control on sedimentation in the southern gentle slope of the Dongying Sag, Bohai Bay Basin

Located in eastern China, the Dongying Sag is characterized as a prototypical rift basin with intricate fault systems. While research efforts have traditionally honed in on the geometry and kinematics of the northern steep slope zone, the structural characteristic of the southern gentle slope zone (SGS) have received comparably less attention, with a notable gap in the understanding of the fault's geometry and kinematics. The sedimentary facies distribution of the rift basin is unequivocally linked to structural activity, but previous studies have treated sedimentary facies and structural characteristics in isolation, leading to an unclear comprehension of the factors influencing sedimentary facies distribution. This study leverages 3D seismic data encompassing 650 km2 along with 20 well logs, directing focus on the key fault zones within the SGS (i.e. Chenguanzhuang (CGZ) and Liangjialou (LJL) fault zone). Using methodologies such as seismic-well integration, planar attribute extraction, and throw-stripping, the research studies the geometric and kinematic characteristic of these fault zones, scrutinizes their activity features, and elucidates the interplay between structural and sedimentary processes in both temporal and spatial dimensions. The results show that (1) the CGZ fault zone is characterized by an array of east-west oriented, en-echelon faults, which nucleated during the nascent phases of rifting (Es4). Within the fault zone, the F1 fault exhibits the greatest strike extension, which can be further segmented into three distinct sections: F1-1, F1-2, and F1-3. These segments have undergone a kinematic evolutionary process of “separation-connection-extension” during the Es. Concurrently, the SGS is subject to a supply of sources from an east-west orientation, leading to the development of a delta-gravity flow sedimentary system within the hanging wall of the CGZ fault zone. (2) Conversely, the LJL fault zone exhibits a broom-like , comprising a series of NEE-oriented faults. The predominant faults (i.e. F10, F11, and F13) nucleated during the late rifting phase (Es3u). Concurrent with the Es3u interval, the northern part of the study area developed shallow-water delta within the hanging wall of the LJL fault zone. (3) During the Es3m period, the expansion index of the CGZ fault zone attained its zenith, this has facilitated the formation of gravity flow deposits arising from slumping at the delta front. Subsequently, fault activity within the study area experienced an overall decline, the gentle paleo-topography promotes a large-scale shallow water delta developed in the Es3u. The decreasing activity of the CGZ fault zone and the increasing activity of the LJL fault zone in Es3u drove the depocenter shifting towards the NW.

Tooth Discoloration from 2 Silver Fluorides Used in Adults with Special Needs: A Randomized Trial.

Discoloration of carious lesions after application of silver diamine fluoride lowers patient acceptance and limits its wider use for caries arrest. To assess lesion and tooth color changes from 2 novel silver fluoride (AgF) products and its relationship to caries activity (clinical visuo-tactile scores) and bacterial load (using laser fluorescence with the DIAGNOdent). A split-mouth design was followed, with matched smooth surface carious lesions in the same arch in adults with special needs randomized for 1-min treatments with AgF/potassium iodide (KI) (Riva Star Aqua, SDI) and AgF/stannous fluoride (SnF2) (Caries Status Disclosing Solution; Whiteley). Standardized images taken at baseline, immediately postoperatively, and at 3-mo review were subjected to digital image analysis to calculate delta-E and to track changes in luminosity of carious lesions. Twelve participants were recruited in the study. A total of 56 teeth (28 pairs) were included. Significantly greater changes were seen in treated lesions than in the adjacent noncarious natural tooth structure, both immediately after treatment and at the 3-mo review (P < 0.0001). Color change and caries activity were not affected by tooth type, tooth location, plaque status, salivary status, or special needs condition. AgF/SnF2 caused transitory darkening immediately on application, while AgF/KI caused the immediate formation of yellow deposits (silver iodide). Both products caused significant darkening of treated lesions at 3 mo (P = 0.0009; P = 0.0361), with no differences between them (P = 0.506). Responding lesions showed larger and more perceptible color changes immediately after either AgF application (P = 0.002; P = 0.024). Both AgF products were highly effective for caries arrest in this patient population. Despite minor differences in the appearance of treated lesions at the time of application, both products lead to similar darkening of treated sites at 3 mo. This study shows the usefulness of silver fluoride used in conjunction with potassium iodide or stannous fluoride for achieving caries arrest in smooth surface lesions in adults with special needs. Patients need to be informed that long-term staining of the lesion occurs with both, similar to silver diamine fluoride.