Types Of Deposits Research Articles

Geochemical and geological properties of tin related to ore deposits: A Review

Tin have atomic number 50 and atomic mass 118,71, commonly found as cassiterite in nature. It is one of important elements in low carbon technologies. Nowadays, tin utilized in broad application range from tin can to electronics. Despite many uses, tin is only produced from limited areas. Because of broad application, understanding of tin in nature is important. Tin usually can be found together with wolfram, although it often occurs at different locations. Tin may occur in various ore deposit types such as greisen, vein, skarn, and placer. This article will describe the geochemical and geological properties of tin in nature, especially that related to ore deposits.

Experimental investigations and three-dimensional computational fluid dynamics modeling of sediment transport in tanks influenced by cavities

Sediment transport is a very complex process in urban water systems, and sediment movement mechanisms are poorly understood. However, it is necessary to comprehend sediment transport to optimize stormwater and sewer tank designs for better performance in trapping particulate pollutants. This work focuses on the numerical simulation and experimental investigation of tank sediment transport. In the numerical simulation, a discrete phase model is applied to calculate particle trajectories, and the particle tracking calculation is coupled with the steady-state flow calculation. A user-defined function is developed in the Fluent computational fluid dynamics (CFD) code to implement the settling condition and improve the particle motion predictions. In the experimental work, a back-scattered ultrasonic method is used to measure the velocity field, and the accumulation of particles at the bottom is reproduced by transforming the raw experimental data. The sediment deposition is also recorded photographically, and the trap efficiency is calculated. The CFD and experimental results are compared to estimate the accuracy of the modified settling boundary condition, showing an improvement in the trap efficiency and deposition zone predictions. High water level in the tank corresponds to higher sediment trap efficiency, and sediment deposition type is strongly affected by the water level. Tank length and the presence of cavity alter the sediment deposition zone, and the presence of cavity increases the trap efficiency of tank.

Cobalt Prospectivity Using a Conceptual Fuzzy Logic Overlay Method Enhanced with the Mineral Systems Approach

AbstractThis paper describes mineral prospectivity research conducted in Finland to predict favorable areas for cobalt exploration using the “fuzzy logic overlay” method in a GIS platform and public geodata of the Geological Survey of Finland. Cobalt occurs infrequently as a core product in mineral deposits. Therefore, we decided to construct separate conceptual mineral prospectivity models within the Northern Fennoscandian Shield, Finland, for four deposit types: (1) “Orthomagmatic Ni–Cu–Co sulfide deposits,” (2) “Outokumpu-type mantle peridotite-associated volcanogenic massive sulfide (VMS)-style Cu–Co–Zn–Ni–Ag–Au deposits,” (3) “Talvivaara black shale-hosted Ni–Zn–Cu–Co-type deposits” and (4) “Kuusamo-type (orogenic gold with atypical metal association) Au–Co–Cu–U–LREE deposits”. In addition, we created a model combining till geochemical data with data derived from bedrock drilling and mineral indications, including boulders and outcrops. The mineral prospectivity models were statistically tested with the “receiver operating characteristics” method using exploration drilling data from known mineral deposits as validation sites. In addition, the predictive performance of the models was evaluated by using success rate curves, where the number of previously identified deposits was compared with the area coverage of the predicted highly favorable areas. These results indicate that the knowledge-driven mineral prospectivity method using parameters derived from mineral systems models is effective in defining favorable exploration target areas at the regional scale. This study's innovation lies in its comprehension of the process of evaluating mineral prospectivity when the commodity of interest is not the primary commodity within the mineral system.

Rupture analysis of 12Cr1MoV super-heater tubes in power plants

This study presents a comprehensive investigation of a failed 12Cr1MoV super-heater tube that had been in long-term service. Several characterization techniques such as confocal laser scanning microscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, and electron backscatter diffraction (EBSD) were utilized to analyze the microstructure and surface of the failed steel and to investigate the effect of microstructural components on crack initiation and propagation. The investigations indicate that the formation of various types of deposits which is very common during service may act as insulation on tube surfaces. In this case, increasing the furnace temperature is necessary to regulate the steam temperature in the tubes resulting in the development of local hot spots on the outer surface of the steel which facilitates crack initiation. EBSD measurements revealed that the cracks propagated in both intergranular and transgranular manners with no preferred orientation, propagating through differently oriented grains. Furthermore, the results showed that the presence of hard and brittle chromium carbide around the crack propagation path assists the crack growth. The findings provide valuable insights into the complex mechanisms of crack propagation in super-heater tubes and can be incorporated into the development of the studied material as well as designing the failure mitigation strategies for operating power plant tubes.

The geomagnetic field of the Ukrainian Carpathians and a 3D magnetic model of the Transcarpathian Depression

The article presents the results of a qualitative and quantitative analysis of the geomagnetic field of the Ukrainian Carpathians and 3D magnetic modeling along the PANCAKE geotransect and Transcarpathian Depression, as well as a comparison of the obtained results with fault-block tectonics, deep structure, and distribution of a number of types of endogenous ore deposits and hydrocarbon accumulations.
 It is shown that the overthrust northeastern part of the Carpathian arc lies on the magnetic crust, and the southwestern one — on its non-magnetic lower part, and between the Rava-Rus’ka and Krakovets and Pre-Carpathian faults, the Earth’s crust is magnetized throughout.
 For the territory of the Transcarpathian Depression, the regional and local components of the geomagnetic field were identified for the first time, geological and geophysical characteristics were provided, and their tectonic interpretation was proposed.
 A three-dimensional magnetic model of the Transcarpathian Depression was created taking into account the magnetization of rocks according to measurements. A detailed magnetic model of the upper part of the crustal section of the Transcarpathian Depression was developed. The connection of magnetic sources with fault zones was analyzed; the results were compared with the deep structure and distribution of ore deposits and hydrocarbon accumulations.
 The regional source with magnetism І=1.0 A/m is located within the Mukachevo Depression and is located at a depth of 6.0 km to 13 km. The local component of the geomagnetic field reflects the magnetic inhomogeneity of the Earth’s crust in the upper 3—4 km of the section and mainly reflects the volcano-tectonic structures and dike formations of the Vyhorlat-Gutyn Ridge, the Chop-Berehove Uplift, and the Velika Dobron’ Uplift. The maximum depths of magnetic sources (up to 3.5 km) and their magnetization (1.22 A/m) are characteristic of the structures of the Vyhorlat-Gutynsky Ridge, intermediate values of depths (2.0—3.0 km) and magnetization (up to 0.93 A/m) belong to the Chop-Berehove Uplift, and the minimum depths (up to 1.1 km) and magnetization (up to 0.7 A/m) are characteristic of the Velika Dobron’ Uplift.
 It is shown that the gas fields of Transcarpathia correspond to local positive magnetic anomalies and are localized above a deep magnetic source. Within the Berehove Uplift, positive anomalies and magnetic sources indicate andesiteporphyrite shafts and andesite domes of Sarmatian age associated with gold, gold-polymetallic and silver mineralization. A zone of antimony mineralization is associated with the Pannonian-Pontic volcanic structures along the southern foot of the Vyhorlat-Gutyn Ridge, and deposits and occurrences of bismuth and mercury correlate well with intrusive formations of the Dacian-Romanian age.

Constraints on metallogenic temperature and mineralization style from reflection color of sphalerite

The relationship between the color of sphalerite and trace elements has aroused the interest of researchers since a long time, but most of the study is still in the qualitative stage. In this contribution, we made attempt to reveal the relationship between the reflection color and its trace element, in order to discuss the genetic significance of various reflection colors of sphalerite through the quantitative study of reflection color of sphalerite. Based on LA-ICP-MS analysis and microspectrophotometer analysis of sphalerite samples in different types of deposits, the elements with significant correlation with the reflection color index were found and analyzed by factor analysis. Different genetic types of sphalerites have different color index, The average reflection color indices of each type sample are as follows, sphalerite from Mengya’a deposit: λd = 477.3 nm, Pe = 0.046, Rvis = 17.23%; sphalerite from Zhaxikang deposit: λd = 477.2 nm, Pe = 0.043, Rvis = 16.70%; sphalerite from Nanmushu deposit: λd = 476.4 nm, Pe = 0.038, Rvis = 16.55%. The reflection color index of sphalerite is correlated with the content of Mn, Fe, Ga, Ge, Ag, Cd, In, Tl, Pb. The results of factor analysis indicate that sphalerite with high reflectivity is more abundant in Fe, Mn and In, while the sphalerite with low reflectivity is more abundant in Ge, Tl, Pb and Ag. Furthermore, the reflection color index of sphalerite can be used to distinguish the genetic type of deposits. Based on an obvious linear relationship between the reflection color index of sphalerite and its mineralization temperature, we propose a new empirical equation: T(°C) = 61.4*Rvis + 1.1*λd + 6000*Pe-1533 which can be used as a geological thermometer.

Stabilization of Platinum Catalyst Surface-Treated by Atomic Layer Deposition of Cobalt for Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) are attracting attention as next-generation energy-conversion devices because they are environmentally friendly and have high energy-conversion efficiencies. A membrane electrode assembly (MEA), composed of an anode, membrane, and cathode, is the most important part of a PEMFC where electrochemical reactions occur. A Pt/C catalyst, wherein Pt is supported on a carbon, is used as the catalyst layer for the anode and cathode. However, as Pt is a precious metal, current research is focused on reducing its loading and improving durability of PEMFCs. This study focused on improving the durability of catalysts by suppressing agglomeration, one of the degradation mechanisms of Pt catalysts. A protective layer of Co metal was deposited using the atomic layer deposition (ALD) process to improve the durability of catalysts. The ALD process is a type of chemical vapor deposition (CVD) process. This process is suitable for the PT/C catalyst as it allows for the deposition of a uniform thin film even on the porous catalyst layer. If the protective layer is thick, it may block the active site of the catalyst, resulting in decreased activity and reduced performance. However, ALD can form a thin protective layer because it can be controlled at the atomic level by adjusting the number of cycles. After fabricating a single cell using ALD Co-Pt/C as a catalyst for the cathode, The U.S. Department of Energy's electrocatalyst durability protocol was used for an accelerated degradation test (ADT). After Co-ALD was used as a cathode for 10 and 20 cycles, the active area of the Pt catalyst particles was reduced owing to the metal Co protective layer. The initial performance and electrochemical surface area (ECSA) of Co-ALD 10, 20 cycles decreased compared to the case of using Co-ALD 0 cycle. However, after ADT, the performance and ECSA reduction rate rather decreased, confirming that the co-protective layer through the plasma-enhanced atomic layer deposition (PEALD) process can improve the durability of the Pt/C catalyst. To identify the cause of the durability improvement, the cathode catalyst particles before and after ADT were compared through high resolution transmission electron microscopy (HR-TEM) analysis. As a result, in the HR-TEM images after ADT, the Pt catalyst particles were relatively uniformly distributed on the carbon support in the Co-Pt/C catalyst compared to Co-ALD 0 cycle. In addition, it was confirmed that the size of the Pt catalyst particles of Co-Pt/C was smaller than that of bare Pt/C (Co-ALD 0 cycle). It was concluded that when the Co protective layer was deposited on the Pt/C cathode, the protective layer suppressed the agglomeration of Pt catalyst particles, therefore, the increase in Pt particle size improved compared to the Co-ALD 0 cycle, and it was revealed that durability improved by suppressing catalyst degradation.

Gold metallogeny in Iran; implications for gold exploration and conceptual modelling

Significant progress in the classification, definition and understanding of the main Au deposit types could significantly aid improvements in Au exploration. Because of the wide occurrence of Au in the central part of the Tethyan Eurasian Metallogenic Belt, Iranian structures composed of more than 17 zones (arcs and blocks) are considered as having one of the largest Au reserves in the Middle East. Without attempts at understanding the tectono-magmatic evolution of Iran and the geodynamic settings of Au deposition, the establishment of a reliable predictive exploration model for Au-type deposits in Iran and other parts of the world will be unsuccessful. By considering a total of 33 Au deposits and prospects in Iran, a mineralization sequence is revealed from orogenic and volcanogenic massive sulfide (VMS), orogenic, Carlin-type, epithermal/porphyry Cu–Au/skarn, epithermal/iron oxide–copper–gold (IOCG). The trend of deposition gradually changes in the SW–NE axis to intrusion-related, epithermal and porphyry Cu–Au deposits at the Urumieh–Dokhtar Magmatic Arc (UDMA) and post-arc magmatism. VMS deposits occur adjacent to the NE Zagros Fold and Thrust Belt, at the Sanandaj–Sirjan Zone. The Zagros Orogeny and associated post-collisional magmatism at UDMA host many porphyry, epithermal and intrusion-related Au deposits, with a major magmatism peak in the Miocene. This work reveals that orogenic and Carlin-type Au mineralization are linked genetically. After each associated subduction for Palaeotethys (286–215 Ma) and Neotethys (210–68 Ma) in Iran, VMS and orogenic Au-deposits are formed in the border of the subduction (±obduction) zone. The porphyry, intrusion-related, epithermal and IOCG mineralization are emplaced in appropriate formations and structures during collision and post-collision processes.

A Fluid Chemical Study of the World-Class, Intrusion-Related Archean Windfall Gold Deposit, Quebec, Canada

Abstract Windfall is a world-class Archean intrusion-related Au deposit (7.4+ Moz of Au) located in the underexplored Urban-Barry greenstone belt (Quebec, Canada). The deposit remains an enigmatic Au setting—its intrusion-related features contrast with the more common orogenic deposit type in the Au-endowed Abitibi greenstone belt. Mineralization consists of quartz-pyrite-carbonate ± tourmaline veins and stockworks that cut sericite-pyrite ± silica ± tourmaline ± fuchsite replacement zones, all of which overprint a swarm of 2697.6 ± 2.6 Ma quartz-feldspar porphyry dikes. That the ore zones and quartz-feldspar porphyry dikes are cut by a later set of 2697.6 ± 0.4 Ma quartz-feldspar porphyry dikes constrains mineralization temporally and spatially to intrusive activity. To further address the deposit genesis, ore petrology integrated with scanning electron microscopy-energy dispersive spectrometry analysis and cathodoluminescence imaging, laser ablation-inductively coupled plasma-mass spectrometry mapping of pyrite, fluid inclusion studies, and in situ secondary ion mass spectrometry isotopic studies (O, S) were completed. Ore-related sulfides are dominated by pyrite with lesser arsenopyrite, sphalerite, chalcopyrite, tennantite-tetrahedrite, galena, gold, electrum, and minor Sb-rich and telluride alloys. Four pyrite generations (Py1-Py4) occur, with elemental maps indicating primary Au is related to As-rich Py2 that is also enriched in Ag-Sb-Hg-Cu-Zn-Pb-Bi-Te. The δ34Spyrite values are similar for Py1 to Py3, with an inferred δ34Sfluid of ~5‰ consistent with a magmatic reservoir, whereas δ18Oquartz for both igneous (avg = 8.4‰, n = 28) and vein (5.7–14.6‰, n = 53) material suggests mixing of a magmatic fluid with an 18O-poor reservoir. Fluid inclusion studies from pre- to postmineralization veins indicate the predominance of a carbonic (±CH4) fluid, with rare aqueous-carbonic (CO2 = 5–98 mol %) and variably saline aqueous types. Whereas the data are considered to best reflect an intrusion-related deposit model, we note that some data, such as the carbonic-rich nature of fluid inclusions and large range in δ18Oquartz, are equivocal in regard to their meaning, and thus further studies are needed to resolve some aspects of this ore system.

LA–ICP–MS analysis of sulfides from the Jianzhupo deposit, Guangxi Province, China: Insights into element incorporation mechanisms and ore genesis

The Jianzhupo deposit, the largest Zn-Sb deposit in the Wuxu orefield in China, contains abundant sphalerite and jamesonite, contrasting with typical Sb deposits elsewhere. Whether the Sb and Zn in the deposit derived from similar parental sources is not clearly resolved. Here, trace-element compositions of sulfides from the deposit were determined by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Results indicate that jamesonite is an important Cd-bearing sulfide with Cd contents of 523–764 ppm and minor or no significant Cd variations were observed within jamesonite crystals. Trace-element compositions of jamesonite indicates that Cd enters the lattice by coupled substitution as 2Fe2+ ↔ Zn2+ + Cd2+. Due to similar geochemical behaviors between Zn and Cd in hydrothermal systems, Zn/Cd ratio of sphalerite was suggested as a robust geochemical tracer to distinguish metal sources in such systems. Here, we summarized the Zn/Cd ratios of sphalerite from various hydrothermal systems and the results show that values between 169 and 233, and lower than 44 are from high- and low-temperature temperature fluid conditions, respectively. Due to different Zn/Cd ratios between sediments and igneous rocks, we conclude that metals in sphalerite from the Jianzhupo deposit were likely derived from granite; in contrast, metals in jamesonite were related to sedimentary rocks. These conclusions are consistent with previous studies on the deposit. Overall, our results indicate that ore-forming fluids of the Jianzhupo deposit were derived from magmatic–hydrothermal and basin water. This study extends the application of trace-element compositions in resolving the sources of sulfides in hydrothermal systems.

Hydrogeologic and magmatic controls on phreatomagmatism at the La Garrotxa monogenetic volcanic field (NE of Iberian Peninsula)

Phreatomagmatism caused by direct interaction of erupting magma and groundwater is a common phenomenon accompanying monogenetic volcanism. The controls on the type of phreatomagmatic phases and deposits that can be observed in such eruptions have been attributed to magma ascent rate, magma rheology, magma discharge, magma vesiculation, water availability, and the properties of the interacting aquifer (i.e., permeability, pore water pressure, recharge rate, etc.). The La Garrotxa monogenetic volcanic field displays a wide variety of eruption sequences and deposits among its 50 volcanoes, half of them including phreatomagmatic phases with very distinct characteristics. Using the characteristics of the phreatomagmatic deposits, including the lithology and content of the accidental lithic fragments, and the substrate stratigraphy and its hydrogeology through the analysis of available information on the water wells and boreholes of the area, it is evident that several aquifers with very different lithologic and hydraulic properties have interacted with the erupting magmas. Moreover, these same data show that all the phreatomagmatic explosions nucleated at a maximum depth of 200 m. These results suggest that pressure variations inside the eruptive conduit, caused by changes in the recharge rate from the magmatic plumbing system, have played a major role in controlling phreatomagmatism, rather than due to variation of the lithological and hydraulic properties of aquifers.

Xenotime reveals Caledonian hydrothermal overprint on Neoproterozoic Cu mineralization, East Greenland

Constraining the age of many types of ore deposits remains challenging because of the lack of radiogenic isotopes incorporated into common ore-forming minerals. The timing of pre-Caledonian-hosted Cu mineralization along the entire c. 1200 km long East Greenland Caledonides remains virtually unknown, hampering our knowledge of ore deposit timing and genesis in a frontier exploration region. Here, automated mineral analysis of a series of nodular, disseminated and vein-hosted Cu- ± Pb-mineralized metasedimentary rocks in central East Greenland reveals detrital zircon and hydrothermal xenotime, both amenable to U–Pb geochronology. Detrital zircon geochronology of a co-deposited quartzite reveals an age distribution highly similar to the Cryogenian ( c. 700 Ma) upper Eleanore Bay Supergroup. Hydrothermal xenotime U–Pb analyses adjacent to nodular and disseminated chalcocite across three proximal samples have variable amounts of common Pb that together yield a well-defined single discordia with a lower concordia intercept of 438 ± 13 Ma (2 σ ). This age is within uncertainty of the onset of Caledonian regional metamorphism and granitoid production and clearly post-dates deposition of the upper Eleanore Bay Supergroup by several hundred million years. Considering a published chalcocite Pb–Pb isochron age of 680 ± 65 Ma, the hydrothermal xenotime U–Pb ages imply that Caledonian-driven fluid activity, sourced from metamorphic reactions or from granitoids, remobilized diagenetic Cu and Pb mineralization. Chalcocite Pb–Pb isotopes show that dissolved and reprecipitated portions are volumetrically minor, radiogenic and Pb-poor, implying that fluids stripped most of the Pb from the system. Thus, it is likely that remobilization was localized on the grain scale, although some Cu and Pb was transported away from diagenetic sites, perhaps into veins. Although Caledonian metamorphism and granitoid emplacement is widespread in central East Greenland, the full extent of their roles in upgrading Cu mineralization remains to be ascertained. Supplementary material: Supplementary figures and tables are available at https://doi.org/10.6084/m9.figshare.c.6675384 Thematic collection: This article is part of the Caledonian Wilson cycle collection available at: https://www.lyellcollection.org/topic/collections/the-caledonian-wilson-cycle

Chlorite geochemical vectoring of ore bodies: a natural kind clustering approach

Chlorite has long been considered a mineral group likely to have different trace element chemistry with proximity to mineralization, and therefore can be used to vector towards ore bodies. However, due to their geochemical complexity, it has proven challenging to develop a simple vectoring method based on the variation in abundance of one or a few chemical elements or isotopes. Machine learning, specifically cluster analysis, provides a potential mathematical tool for characterizing multidimensional geochemical correlations with proximity to mineralization. In this contribution we conducted a cluster analysis on 23 elements from 1,679 distinct chlorite sample analyses. The combination of this clustering technique with classification by proximity to the ore body, 1) explores and characterizes the nature of chlorite composition and proximity to ore bodies and 2) tests the efficacy of clustering-classification methods to predict whether a chlorite sample is near to an ore body. We found that chlorite chemistry is more strongly controlled by deposit type than proximity to mineralization and that cluster analysis of chlorite trace element content is likely not a viable way to develop vectors towards porphyry mineralization.

The Wuliping ion-adsorption deposit, Guizhou Province, South China: A new type of rhenium (Re) deposit

Rhenium (Re) is an extremely rare element and was also the last stable (non-radioactive) element discovered. Owing to the extremely high melting point, Re is ideal for high-temperature applications, for example, as an alloying metal for jet engine turbine blades. This, in turn, leads to an increasing demand for Re resources. Previous studies show that the most common host minerals for Re in the Re-bearing deposits are sulfides (especially molybdenite), and to a lesser extent, U minerals and organic matter. In this study, we report high Re grades and the corresponding host minerals in the weathered Shangsi Formation (dominated by mudstone) of the Wuliping Pb-Zn-Mo polymetallic deposit, based on whole-rock major and trace element geochemical, TOC, XRD, SEM-EDS, and LA-ICP-MS analyses. We find that all weathered samples from the Shangsi Formation display noticeable enrichment of Re (and also Mo), with Re concentrations ranging from 12.61 to 93.13 ppm (averaging 28.23 ppm versus <0.1 ppb in the upper continental crust). However, the high Re concentrations are not found in either sulfides (e.g., molybdenite) or organic matter; rather, our results reveal that Re is mainly adsorbed by kaolinite. We propose that the Wuliping ion-adsorption deposit should be a new type of ion-adsorption Re deposit, which is noticeably different from known Re deposit types. We suggest that ion-adsorption deposits, such as the one explored in this study, may become one of important sources of critical metals in this era of ever increasing demand.

Modes of occurrence of critical metals (Nb-Ta-Zr-Hf-REY-Ga) in altered volcanic ashes in the Xuanwei Formation, eastern Yunnan Province, SW China: A quantitative evaluation based on sequential chemical extraction

Altered volcanic ash with highly-elevated concentrations of Nb(Ta), Zr(Hf), Ga, and rare earth elements and yttrium (REY) is an untraditional type of critical metal deposit that has been discovered in Yunnan Province, southwest China. Previous studies have briefly described the modes of occurrence of Nb(Ta)-Zr(Hf)-REY-Ga in the ore deposit, showing that Zr and Hf are mostly hosted in zircon; light rare earth elements (LREE) mainly occur in REY-bearing carbonates and phosphates; Nb and Ta are primarily hosted in the former Fe-Ti oxide phases and zircon; and Ga is predominantly associated with clay minerals. However, previous studies of the modes of occurrence of critical metal elements (Nb-Ta-Zr-Hf-REY-Ga) have been limited to qualitative or semi-quantitative studies of individual mineral grains, and quantitative research of the modes of occurrence of these elements in whole rocks is absent. This paper quantifies the modes of occurrence of critical elements (Nb-Ta-Zr-Hf-REY-Ga) using a sequential chemical extraction method. The results show that about 65.3–86.7% Nb is associated with hydrofluoric acid (HF)-soluble aluminosilicates (clays) and 13.3–34.7% in the insoluble phases such as Nb-rutile. Approximately 87.6–90.2% Zr is the primary hosted in zircon and 9.5–12.0% Zr appears to be associated with HF-soluble aluminosilicates in the altered volcanic ash. In felsic altered volcanic ashes (Al2O3/TiO2 ratio between 21 and 70), the REY are predominantly in the authigenic minerals such as REY-bearing aluminum phosphates and sulfates of the alunite supergroup (APS minerals), carbonates or fluorocarbonates. About 74.0–89.4% LREE, 26.5–34.2% middle rare earth elements (MREY), and 22.1–24.8% heavy rare earth elements (HREE) occur in HF-soluble aluminosilicates. In intermediate altered volcanic ash samples (Al2O3/TiO2 ratio between 8 and 21), 93.0% LREE are associated with insoluble phases such as monazite and zircon. Gallium is predominantly associated with HF-soluble aluminosilicates (73.3–80.5%) in all altered volcanic ash samples.

Compositional Signatures of Gold from Different Deposit Types in British Columbia, Canada

A study of both in situ and detrital gold from different deposit types in British Columbia was undertaken to establish deposit-specific compositional characteristics in terms of alloy composition and suites of mineral inclusions. The study is based on 11,840 particles from 160 localities in which nine gold deposit types are represented, although there is a strong bias towards gold of orogenic, low-sulphidation epithermal, and alkalic porphyry origin. In general, Ag values in gold alloys are not a powerful discriminator for deposit type, but minor metals may prove useful where detectable, e.g., Cu in gold from ultramafic associations and Pd and Hg in gold from alkalic porphyry systems. The characterization of inclusion suites is far more illuminating, as they correlate strongly with the mineralogy of auriferous ores from different deposit types. This outcome has confirmed the validity of designing an indicator methodology based on inclusion suites and has permitted the prediction of inclusion suites for gold from other deposit types where data are more scarce. The compositional templates generated in the study were applied to identify the source deposit type(s) of gold from 41 localities (a total of 2916 detrital gold particles) where gold genesis was previously unknown.

Link Mo isotopes to the sources of the Paleoproterozoic Mo mineralization in the Qinling orogen

Longmendian and the Zhaiwa are the two oldest Mo deposits in the Qinling orogenic belt, China, which is one of the most important Mo provinces in the world with numerous and diverse types of Mo deposits that experienced multistaged mineralization. Here we investigated Mo isotope compositions in molybdenite and rocks from the Longmendian and the Zhaiwa Paleoproterozoic Mo deposits to link Mo isotopes to the sources of Mo metal. The significant Mo isotope variation in the Longmendian and the Zhaiwa Mo deposits (δ98Mo = −0.51‰ to + 1.01‰ and −0.37‰ to +0.53‰, respectively, relative to NIST-3134) may be controlled by Rayleigh and equilibrium fractionation. The different distributions of Mo isotope compositions of molybdenite in the two deposits may be caused by the physiochemical differences in ore-forming systems. The high Mo content of the Taihua Supergroup and the Xiong’er Group, combined mean values of Mo isotopes between molybdenite and whole rocks suggested that the two stratigraphic units would be the main contributor of Mo for the Paleoproterozoic Mo mineralization that mixed with small proportions of isotopically lower values of the mantle.

TUNEL-positive structures in activated microglia and SQSTM1/p62-positive structures in activated astrocytes in the neurodegenerative brain of a CLN10 mouse model.

Neuronal ceroid lipofuscinosis is a group of pediatric neurodegenerative diseases. One of their causative genes, CLN10/CtsD, encodes cathepsin D, a major lysosomal protease. Central nervous system (CNS)-specific CtsD-deficient mice exhibit a neurodegenerative disease phenotype with accumulation of ceroid lipofuscins, granular osmiophilic deposits, and SQSTM1/p62. We focused on activated astrocytes and microglia in this neurodegenerative mouse brain, since there are few studies on the relationship between these accumulators and lysosomes in these glial cells. Activated microglia and astrocytes in this mouse thalamus at p24 were increased by approximately 2.5- and 4.6-fold compared with the control, while neurons were decreased by approximately half. Granular osmiophilic deposits were detected in microglial cell bodies and extended their processes in the thalamus. LAMP1-positive lysosomes, but not SQSTM1/p62 aggregates, accumulated in microglia of this mouse thalamus, whereas both lysosomes and SQSTM1/p62 aggregates accumulated in its astrocytes. TUNEL-positive signals were observed mainly in microglia, but few were observed in neurons and astrocytes. These signals were fragmented DNA from degenerated neurons engulfed by microglia or in the lysosomes of microglia. Abnormal autophagic vacuoles also accumulated in the lysosomes of microglia. Granular osmiophilic deposit-like structures localized to LAMP1-positive lysosomes in CtsD-deficient astrocytes. SQSTM1/p62-positive but LAMP1-negative membranous structures also accumulated in the astrocytes and were less condensed than typical granular osmiophilic deposits. These results suggest that CtsD deficiency leads to intracellular abnormalities in activated microglia and astrocytes in addition to neuronal degeneration.

A retrospective study on the direct immunofluorescence findings in pigmented purpuric dermatosis.

Pigmented purpuric dermatosis (PPD) is characterized by grouped petechiae, purpuric macules, and pigmentation in the bilateral lower extremities. It runs a chronic and relapsing course. Pathophysiology is poorly understood, but it has been proposed to be an immune-complex disease or capillaritis. This study aimed to determine the incidence and patterns of positive direct immunofluorescence (DIF) findings in patients with clinically and histopathologically confirmed PPD. The association between DIF deposition type and clinical profile was also analyzed. Patients with a clinical and histopathologic PPD diagnosis who had undergone DIF studies at a tertiary medical center with attached dermatopathology and immunofluorescence diagnostic centers between January 2002 and December 2021 were included in this study. Data on age, sex, disease duration, comorbidities, and drug intake were collected from medical records. There were 65 patients who satisfied the inclusion criteria. Among them, 58 (89%) had at least one positive finding and 53 (82%) were vascular deposition of immunoglobulin (Ig), complement, or fibrinogen. The most common vascular deposition was fibrinogen (71%) followed by C3 (62%), IgM (18%), IgA (6%), and IgG (3%). Fibrinogen deposition was associated with hypertension (p < 0.03). There was no association between vascular DIF deposition of IgG, IgA, and C3, with age, sex, comorbidities, disease duration, and drug history. The most common DIF findings in PPD were vascular deposition of fibrinogen and C3, with or without Ig presence. DIF findings supported a vascular origin in PPD but not an immune complex-mediated disease. Hypertension was associated with fibrinogen deposition and may play a role in its pathophysiology.

Possible genetic relationship between Mesozoic magmatic rocks and gold mineralization in the Jiaodong Peninsula (Eastern China): constraints of magmatic evolution and physicochemical conditions

The Jiaodong Peninsula is China’s largest gold province and the third largest in the world. Although gold mineralization is associated with Mesozoic granites temporally and spatially, the specific genetic association remains unclear, leading to ambiguity regarding the genetic type of gold deposits. To address this issue, we conducted whole-rock major and trace elements, LA–ICP–MS zircon U–Pb geochronology and trace elements geochemical analyses on the Linglong (Linglong suite), Yashan, and Nansu (Weideshan suite) plutons, and compiled contemporaneous magmatic rock data. Our results show that the granites were emplaced at 161 ± 2, 118 ± 1, and 121 ± 2 Ma, respectively. Geochemically, these rocks exhibit high Al2O3 (12.73–14.10 wt%) content and Sr/Y (35.54–136.50) ratio, and low Y (3.26–11.20 ppm) and Yb (0.33–0.97 ppm) contents, indicating the adakitic rock properties. They were formed through partial melting of the thickened lower crust associated with subduction of the paleo-Pacific Plate. The Early Cretaceous granites contain a large amount of mafic microgranular enclaves, indicating the presence of mantle material mixing in the source area. Zircon trace elements show that the pre-mineralization magma (Linglong) had relatively low oxygen fugacity and temperature (ΔFMQ = −2.5 to +1.9, T-Ti in zircon (mean) = 740°C) compared to the mineralization magma (ΔFMQ = +0.5 to +3.9, T-Ti in zircon (mean) = 755°C). The physicochemical conditions in the pre-mineralization magma source area may be favorable for sulfide accumulation (may including gold). During the Early Cretaceous, North China Craton decratonization reached its climax, and a large number of adakitic crust-mantle mixed oxidized magma upwells, allowing for the migration and mineralization of a large amount of sulfides and gold. This model helps explain the transient, explosive, and genetic categories in Jiaodong gold deposits.