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Volume 12
Issue 7
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Minerals, Volume 12, Issue 7 (July 2022) – 134 articles

Cover Story (view full-size image): Mineral inclusions in diamonds represent a window into the minerals and rocks in the upper mantle, and thus provide a unique opportunity to gain crucial information about the chemical and physical environment during their formation in the upper mantle. Polishing-exposed mineral inclusions in diamonds from the No. 50 kimberlite diatreme of China include olivine, chromite, garnet, orthopyroxene, Ca carbonate, magnesite, dolomite, norsethite, pyrrhotite, pentlandite, troilite, unknown hydrous magnesium silicate, Fe-rich phase, etc. This study using electron probe microanalysis and microscopy shows that a metasomatic enrichment event occurred in the diamond source region below the North China Craton and that the diamonds were likely formed by solid-state growth under metasomatic conditions. View this paper
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14 pages, 3926 KiB  
Article
Cycling of Pt, Pd, and Rh Derived from Catalytic Converters: Potential Pathways and Biogeochemical Processes
by Ioannis-Porfyrios Eliopoulos, George Eliopoulos, Theodora Sfendoni and Maria Economou-Eliopoulos
Minerals 2022, 12(7), 917; https://doi.org/10.3390/min12070917 - 21 Jul 2022
Cited by 5 | Viewed by 1737
Abstract
The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming [...] Read more.
The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming to assess the auto-catalyst-derived environmental impact to the large city of Athens and the potential human health risk. The determined mean values of 314 Pt, 510 Pd, and 23 Rh (all in μg/kg) in dust samples are much lower than the 2070 μg/kg Pt and 1985 μg/kg Pd contents in gully pots in the Katechaki peripheral highway and higher than the mean values of 230 Pt, 300 Pd, and 13 Rh (all in μg/kg) in the soil samples. With the exception of two samples from gully pots, from 51% to 70% of the samples (for the Pd and Pt, respectively) fall in the range from 100 to 400 μg/kg. The calculated accumulation factors showed means of 3.88 μg/kg Pd and 2.95 μg/kg Pt for plants and tree leaves, but any significant difference (t-test) is lacking, and they are much lower than those reported for roots of plants (literature data). Although the Pt, Pd, and Rh bioaccumulation factors for shoots of plants/crops are relatively low, the increasing number of cars with catalytic converters in Greece and the relatively high bioaccumulation in the food chain may highlight a potential risk for human health and ecosystems, and the need for special attention on their bioaccumulation and bioaccessibility on a global scale. Full article
(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)
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15 pages, 5088 KiB  
Article
Response of Travertine Dam to Precipitation over the Past 800 Years in Zabuye Salt Lake, Southwestern Tibetan Plateau
by Mingming Li, Mianping Zheng, Chuanyong Ye, Chenguang Wang, Xuefei Zhang, Xuefeng Wang, Yuanyi Zhao and Yanbo Zhang
Minerals 2022, 12(7), 916; https://doi.org/10.3390/min12070916 - 21 Jul 2022
Cited by 3 | Viewed by 1679
Abstract
The Tibetan Plateau is known as the core area of the third pole of the Earth and is a key area for global climate change research. This study uses the Zabuye Salt Lake travertine dam as the research object and U–Th dating as [...] Read more.
The Tibetan Plateau is known as the core area of the third pole of the Earth and is a key area for global climate change research. This study uses the Zabuye Salt Lake travertine dam as the research object and U–Th dating as the chronological framework and proposes that the carbon and oxygen isotopes of travertine can be used as a precipitation index through the analysis of hydrogen and oxygen isotopes of spring water, and petrology, mineralogy, carbon and oxygen isotopes of travertine. The precipitation records of Zabuye Salt Lake over the last 800 years show a dry condition in 1191–1374 AD (Medieval Warm Period), a humid condition in 1374–1884 AD (Little Ice Age), and a dry condition in 1884–1982 AD (Current Warn Period), indicating a warm–dry/cold–moist climate pattern, which is consistent with precipitation records from many places on the Tibetan Plateau. We preliminarily point out that travertine can record the evolution of paleoprecipitation (paleomonsoon) at least on the decadal–centennial scale. The Indian summer monsoon has been the main factor influencing precipitation change in Zabuye Salt Lake over the past 800 years, and the change in evapotranspiration intensity caused by temperature change driven by solar radiation is also an important factor affecting dry–moist change. Full article
(This article belongs to the Special Issue Geochemistry of Travertines and Calcareous Tufas)
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15 pages, 4097 KiB  
Article
Magnetotelluric Responses of an Anisotropic 1-D Earth with a Layer of Exponentially Varying Conductivity
by Linjiang Qin, Weifeng Ding and Changfu Yang
Minerals 2022, 12(7), 915; https://doi.org/10.3390/min12070915 - 21 Jul 2022
Cited by 4 | Viewed by 1412
Abstract
The magnetotelluric (MT) sounding of a layered Earth model involving a transitional layer has been widely studied, and MT responses of the model with dipping anisotropic conductivity have also been treated. However, a model incorporating both a transitional layer and dipping anisotropy has [...] Read more.
The magnetotelluric (MT) sounding of a layered Earth model involving a transitional layer has been widely studied, and MT responses of the model with dipping anisotropic conductivity have also been treated. However, a model incorporating both a transitional layer and dipping anisotropy has seldom been considered. The analytical solution of such a geoelectrical model including three layers was derived in this study. The middle layer was a transitional layer with conductivity exponentially varying with depth, which was covered by a homogeneous layer and underlaid by a dipping anisotropic half-space. The electromagnetic (EM) fields in the transitional layer were explicitly solved with modified Bessel functions. The surface impedance was calculated recursively. The dependence of the apparent resistivity and impedance phase as well as the EM fields on different model parameters were investigated in detail. We believe that our analytical solution provides a useful complement to the theory of the one-dimensional (1D) inversion and interpretation based on the layered model with fixed conductivity. Full article
(This article belongs to the Special Issue Electromagnetic Exploration: Theory, Methods and Applications)
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20 pages, 89459 KiB  
Article
The Extraordinary Variety and Complexity of Minerals in a Single Keokuk Geode from the Lower Warsaw Formation, Hamilton, Illinois, USA
by Nova Mahaffey and Robert B. Finkelman
Minerals 2022, 12(7), 914; https://doi.org/10.3390/min12070914 - 21 Jul 2022
Viewed by 1969
Abstract
We performed an extensive optical and chemical analysis of a single Keokuk geode using electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy that revealed an extraordinary array of minerals and multiple, complex cycles of mineralization. We identified at least 15 minerals including [...] Read more.
We performed an extensive optical and chemical analysis of a single Keokuk geode using electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy that revealed an extraordinary array of minerals and multiple, complex cycles of mineralization. We identified at least 15 minerals including 5 that, to our knowledge, have not been reported in previous studies of these geodes. Along with bitumen we have described the occurrence of REE’s, and other unidentified phases containing metals such as chromium, nickel, molybdenum, tin, copper, zinc, and lead. Additionally, preliminary thin-section analysis reveals the occurrence of the tentatively identified minerals zircon, rutile, and xenotime as well as grains containing gold and silver within the chalcedony shell. The presence of these potentially economically valuable minerals warrants further investigation into the micro-minerology of Keokuk geodes. Our SEM/EDX analysis reveals an array of complex mineral assemblages, intergrowths, and inclusions that help chronologically link multiple stages of paragenesis occurring in different locations within the geode. Consequently, morphology and intricate microstructures provide a window into the extreme complexity of mineral crystallization. The majority of micro-minerals we have observed correspond with the later stages of geode paragenesis, thus providing a detailed record of the secondary mineralization processes which occurred over thousands to millions of years. Full article
(This article belongs to the Special Issue Mineral/Ore Growth: From the Ions to the Macrocrystals)
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22 pages, 20380 KiB  
Article
Identification of Diagenetic Facies Logging of Tight Oil Reservoirs Based on Deep Learning—A Case Study in the Permian Lucaogou Formation of the Jimsar Sag, Junggar Basin
by Ming Qi, Changcheng Han, Cunfei Ma, Geng Liu, Xudong He, Guan Li, Yi Yang, Ruyuan Sun and Xuhui Cheng
Minerals 2022, 12(7), 913; https://doi.org/10.3390/min12070913 - 20 Jul 2022
Cited by 4 | Viewed by 1308
Abstract
As a typical tight oil reservoir in a lake basin, the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin has great potential for exploration and development. However, at present, there are few studies on the identification of the diagenetic facies [...] Read more.
As a typical tight oil reservoir in a lake basin, the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin has great potential for exploration and development. However, at present, there are few studies on the identification of the diagenetic facies of tight oil reservoir logging in the study area, and the control effect of diagenesis on tight oil reservoirs is not clear. The present work investigates the diagenesis and diagenetic facies logging of the study area, making full use of core data, thin sections, and logs, among other data, in order to understand the reservoir characteristics of the Permian Lucaogou Formation in the Jimsar Sag. The results show that the Lucaogou Formation has undergone diagenetic activity such as compaction, carbonate cementation, quartz cementation, and clay mineral infilling and dissolution. The diagenetic facies are classified according to mineral and diagenetic type, namely, tightly compacted facies, carbonate-cemented facies, clay mineral-filling facies, quartz-cemented facies, and dissolution facies. The GR, RT, AC, DEN, and CNL logging curves were selected, among others, and the convolutional neural network was introduced to construct a diagenetic facies logging recognition model. The diagenetic facies of a single well was divided and identified, and the predicted diagenetic facies types were compared with thin sections and SEM images of the corresponding depths. Prediction results had a high coincidence rate, which indicates that the model is of a certain significance to accurately identify the diagenetic facies of tight oil reservoirs. Assessing the physical properties of the studied reservoirs, dissolution facies are the dominant diagenetic facies in the study area and are also the preferred sequence for exploration—to find dominant reservoirs in the following stage. Full article
(This article belongs to the Special Issue Reservoir Geology and Oil & Gas Reservoir Characterization)
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20 pages, 4960 KiB  
Article
Petrogenesis and Tectonic Implications of the Ore-Associated Intrusions in Bayanbaolege Ag Polymetallic Deposit, Inner Mongolia, NE China
by Xi Wang, Qun Yang, Zhen-Ming Sun and Yun-Sheng Ren
Minerals 2022, 12(7), 912; https://doi.org/10.3390/min12070912 - 20 Jul 2022
Cited by 2 | Viewed by 1145
Abstract
The large Bayanbaolege Ag polymetallic ore deposit is located in the Tuquan-Linxi Fe (Sn)-Cu-Pb-Zn-Ag-Nb (Ta) polymetallic metallogenic belt, which is an important part of the Great Xing’an Range metallogenic province, northeast China. The sulfide–quartz vein-type orebodies in the deposit are mainly hosted in [...] Read more.
The large Bayanbaolege Ag polymetallic ore deposit is located in the Tuquan-Linxi Fe (Sn)-Cu-Pb-Zn-Ag-Nb (Ta) polymetallic metallogenic belt, which is an important part of the Great Xing’an Range metallogenic province, northeast China. The sulfide–quartz vein-type orebodies in the deposit are mainly hosted in the Cretaceous granodiorite porphyry and Late Permian Linxi formation. The U-Pb dating of the zircon from the post-ore diorite porphyrite yields an age of 124.8 ± 1.1 Ma, which constrains the mineralization time at the Early Cretaceous. The Sr-Nd isotope values (87Sr/86Sr)i = 0.708576~0.710536; εNd (t) = −0.51~+0.69; the Hf isotope values 176Hf/177Hf = 0.2827278~0.2830095, the εHf (t) = +3.1~+11.2, TDM2 = 615~1341 Ma of the metallogenic granodiorite porphyry. The Hf isotope values 176Hf/177Hf = 0.2828596~0.2829451, and the εHf (t) = +5.7~+8.8 of the diorite porphyrite, TDM2 = 827~1108 Ma, indicating that the ore-forming materials were the possible involvement of heterogeneous juvenile sources including moderately depleted mantle and newly underplated lower crust. The major and trace elements (including REEs) implied that these intrusions are the I-type granite and linked intimately to the westward subduction of the Paleo-Pacific Ocean plate. From these whole-rock major and trace elements and zircon U-Pb ages, as well as Sr-Nd-Hf isotope data, we conclude that the ore-associated I-type granites in the Bayanbaolege deposit formed in an extensional tectonic setting of the Early Cretaceous, and are compactly related to the retreat of the Paleo-Pacific Ocean subducted plate linked intimately to the westward subduction of the Paleo-Pacific Ocean plate rather than the closure of the Mongol–Okhotsk Ocean. Furthermore, by integrating geological background work and previous research work, implying the mineralization age of the Bayanbaolege deposit should have been formed in the 125–130 Ma. Full article
(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits)
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25 pages, 6740 KiB  
Article
The Effect of Pre-Oxidation on the Reducibility of Chromite Using Hydrogen: A Preliminary Study
by Jamey Davies, Merete Tangstad, Eli Ringdalen, Johan Paul Beukes, Dmitri Bessarabov and Stephanus Petrus du Preez
Minerals 2022, 12(7), 911; https://doi.org/10.3390/min12070911 - 20 Jul 2022
Cited by 4 | Viewed by 2043
Abstract
The majority of ferrochrome (FeCr) is produced through the carbothermic reduction of chromite ore. In recent years, FeCr producers have been pressured to curve carbon emissions, necessitating the exploration of alternative smelting methods. The use of hydrogen as a chromite reductant only yields [...] Read more.
The majority of ferrochrome (FeCr) is produced through the carbothermic reduction of chromite ore. In recent years, FeCr producers have been pressured to curve carbon emissions, necessitating the exploration of alternative smelting methods. The use of hydrogen as a chromite reductant only yields water as a by-product, preventing the formation of carbon monoxide (CO)-rich off-gas. It is however understood that only the Fe-oxide constituency of chromite can be metalized by hydrogen, whereas the chromium (Cr)-oxide constituency requires significantly higher temperatures to be metalized. Considering the alternation of chromite’s spinel structure when oxidized before traditional smelting procedures, the effects on its reducibility using hydrogen were investigated. Firstly, the effect of hydrogen availability was considered and shown to have a significant effect on Fe metallization. Subsequently, spinel alternation induced by pre-oxidation promoted the hydrogen-based reducibly of the Fe-oxide constituency, and up to 88.4% of the Fe-oxide constituency was metallized. The Cr-oxide constituency showed little to no reduction. The increase in Fe-oxide reducibility was ascribed to the formation of an exsolved Fe2O3-enriched sesquioxide phase, which was more susceptible to reduction when compared to Fe-oxides present in the chromite spinel. The extent of Fe metallization of the pre-oxidized chromite was comparable to that of unoxidized chromite under significantly milder reduction conditions. Full article
(This article belongs to the Special Issue Ferrochrome Waste Management—Addressing Current Gaps for Energy and Material Consumption, Carbon Release, and Waste Beneficiation)
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28 pages, 7219 KiB  
Article
Petrogenesis and Tectonic Implications of the Neoproterozoic Peraluminous Granitic Rocks from the Tianshui Area, Western Margin of the North Qinling Terrane, China: Evidence from Whole-Rock Geochemistry and Zircon U–Pb–Hf–O Isotopes
by Gang Yang, Juan Zhang, Hongfu Zhang, Zhian Bao and Abing Lin
Minerals 2022, 12(7), 910; https://doi.org/10.3390/min12070910 - 20 Jul 2022
Cited by 2 | Viewed by 1856
Abstract
The source and petrogenesis of peraluminous granitic rocks in orogenic belts can provide insights into the evolution, architecture, and composition of continental crust. Neoproterozoic peraluminous granitic rocks are sporadically exposed in the Tianshui area of the western margin of the North Qinling Terrane [...] Read more.
The source and petrogenesis of peraluminous granitic rocks in orogenic belts can provide insights into the evolution, architecture, and composition of continental crust. Neoproterozoic peraluminous granitic rocks are sporadically exposed in the Tianshui area of the western margin of the North Qinling Terrane (NQT), China. However, the source, petrogenesis, and tectonic setting of these rocks still remain unclear, which limits our understanding of the Precambrian tectonic and crustal evolution of the Qinling Orogenic Belt (QOB). Here, we determined the whole-rock geochemical compositions and in situ zircon U–Pb ages, trace-element contents, and Hf–O isotopic compositions of a series of peraluminous granitic mylonites and granitic gneisses in the Tianshui area at the west end of North Qinling. Zircon U–Pb dating revealed that the protoliths of the studied granitic mylonites and granitic gneisses crystallized at 936–921 Ma. The granitic rocks displayed high A/CNK values (1.12–1.34) and were enriched in large-ion lithophile elements (e.g., Rb, Ba, Th, U, and K) and light rare earth elements, and they were depleted of high-field-strength elements (e.g., Nb, Ta, and Ti). These rocks showed variable zircon εHf(t) (−12.2 / 9.7) and δ18O (3.56‰ / 11.07‰) values, suggesting that they were derived from heterogeneous crustal sources comprising predominantly supracrustal sedimentary rocks and subordinate igneous rocks. In addition, the U–Pb–Hf isotopic compositions from the core domains of inherited zircons were similar to those of detrital zircons from the Qinling Group, suggesting that the Qinling Group was an important crustal source for the granitic rocks. The lithological and geochemical features of these granitic rocks indicate that they were generated by biotite dehydration melting of heterogeneous sources at lower crustal depths. Combining our results with those of previous studies, we suggest that the NQT underwent a tectonic transition from syn-collision to post-collision at 936–874 Ma in response to the assembly and breakup of the Rodinia supercontinent. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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13 pages, 4144 KiB  
Article
Clay Mineral Assemblages in the Cretaceous Volcanogenic–Sedimentary Rocks of the North-Western Part of the Transition Zone from the Asian Continent to the Pacific Ocean
by Anatoly V. Mozherovsky
Minerals 2022, 12(7), 909; https://doi.org/10.3390/min12070909 - 20 Jul 2022
Cited by 2 | Viewed by 1229
Abstract
In this study, clay and non-clay minerals in the cement of Cretaceous volcanogenic–sedimentary rocks from the bottom of the marginal seas of the north-western Pacific Ocean and adjacent areas were studied. Corrensite and mixed-layer chlorite–smectite, rectorite and mixed-layer illite–smectite, chlorite, swelling chlorite (?), [...] Read more.
In this study, clay and non-clay minerals in the cement of Cretaceous volcanogenic–sedimentary rocks from the bottom of the marginal seas of the north-western Pacific Ocean and adjacent areas were studied. Corrensite and mixed-layer chlorite–smectite, rectorite and mixed-layer illite–smectite, chlorite, swelling chlorite (?), illite, kaolinite, smectite (?), calcite, ankerite, barite, gypsum, epsomite, zeolites (laumontite, analcime, and stilbite), cristobalite, and quartz were determined. The following are the indicative properties: (a) minerals: corrensite and rectorite; (b) associations: corrensite–chlorite, corrensite–chlorite–laumontite, corrensite–epsomite–authigenic calcite, and quartz–illite. Such minerals indicate that the thickness of the accumulated sediments in the studied basins could reach three to five kilometers and that the temperature of their formation could be higher than 150 °C. Transformations in the process of diagenesis and epigenesis occur in two directions: smectite–rectorite–mica, with an excess of potassium, and smectite–corrensite–chlorite, with an excess of magnesium. The chlorite–corrensite association may indicate conditions favorable for seawater evaporation, and the presence of laumontite in the corrensite–chlorite association suggests a periodic supply of calcium to the sedimentation basin. The illite–kaolinite association is probably associated with coal accumulation in epicontinental conditions and a warm humid climate in nearby areas. Periods of sedimentation, possibly associated with global climate events, were identified: 113–120, 110–113, 105–110, 93–95, 72–83 and 61–72 Ma. The established time intervals and mineral associations can serve as benchmarks for stratigraphic constructions in reconstructing the physicochemical, climatic parameters, and conditions of Cretaceous volcanogenic–sedimentary strata accumulation. Full article
(This article belongs to the Special Issue Geological Evolution of The Cretaceous and Associated Mineralization)
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27 pages, 4870 KiB  
Article
Quaternary Glauconitization on Gulf of Guinea, Glauconite Factory: Overview of and New Data on Tropical Atlantic Continental Shelves and Deep Slopes
by Pierre Giresse
Minerals 2022, 12(7), 908; https://doi.org/10.3390/min12070908 - 20 Jul 2022
Cited by 9 | Viewed by 2508
Abstract
For a long time, particular attention was paid to glauconitization in the surficial sediments lying on the outer continental shelves of present oceans. Subsequently, the processes observed and analyzed may have served as models for studies of glauconite in Cenozoic or even Mesozoic [...] Read more.
For a long time, particular attention was paid to glauconitization in the surficial sediments lying on the outer continental shelves of present oceans. Subsequently, the processes observed and analyzed may have served as models for studies of glauconite in Cenozoic or even Mesozoic shelf deposits. Access to the sedimentary domains of deep oceans, particularly those of contouritic accumulation fields, has made it possible to discover unexpected processes of glauconitization. Thus, the long-term prevalence of control using fairly high-temperature water has become obsolete, and the prerequisite influence of continental flows has come to be considered on a new scale. Frequently, sediments from contouritic accumulation provide a condensed and undisturbed sedimentary record without periods of sediment erosion. Glauconitic grains could possibly integrate the signatures of bottom-water masses over prolonged periods of time, which, while preventing their use in high-resolution studies, would provide an effective means of yielding reliable average estimates on past εNd signatures of bottom-water masses. In this regard, glauconitic grains are probably better-suited to paleoceanographic reconstructions than foraminifera and leached Fe-oxyhydroxide fractions, which appear to be influenced by sediment redistribution and the presence of terrestrial continental Fe-oxides, respectively. Direct methodological access to the compositions of the semi-confined microenvironments of neoformation has largely renewed the information, chemical or crystallographic, that was previously, and for a long time, restricted to macromeasurements. The various granular supports (mudclasts, fecal pellets, and foraminifera infillings) include inherited 1:1 clays (or Te-Oc; i.e., clay minerals consisting of one tetrahedral sheet and one octahedral sheet, such as kaolinite) that are gradually replaced by 2:1 clays (Te-Oc-Te) dominated first by smectite, and then by glauconite. In small pores, the water’s activity is diminished; as a consequence, the precipitation of a great number of mineral species is thereby made easier, and their stability domains are changed. A specific methodological approach allows the study of the mineralogy and chemistry of the fine-scale mineral phases and to avoid the global aspect of the analytical methods previously used in the initial studies. Wide-field micrographs taken at a mean direct magnification of 100.000 show the intimate and characteristic organization of the main phases that occur in a single grain. One or several “fine” (about 10 nanometers in scale) microchemical analyses can be recorded, and directly coupled with each interesting and well-identified structure image observed in HRTEM. Full article
(This article belongs to the Special Issue Formation and Evolution of Glauconite. New Scale Approach)
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19 pages, 11716 KiB  
Article
Ion and Particle Size Effects on the Surface Reactivity of Anatase Nanoparticle–Aqueous Electrolyte Interfaces: Experimental, Density Functional Theory, and Surface Complexation Modeling Studies
by Moira K. Ridley, Michael L. Machesky and James D. Kubicki
Minerals 2022, 12(7), 907; https://doi.org/10.3390/min12070907 - 20 Jul 2022
Cited by 1 | Viewed by 1687
Abstract
At the nanoscale, particle size affects the surface reactivity of anatase–water interfaces. Here, we investigate the effect of electrolyte media and particle size on the primary charging behavior of anatase nanoparticles. Macroscopic experiments, potentiometric titrations, were used to quantitatively evaluate surface charge of [...] Read more.
At the nanoscale, particle size affects the surface reactivity of anatase–water interfaces. Here, we investigate the effect of electrolyte media and particle size on the primary charging behavior of anatase nanoparticles. Macroscopic experiments, potentiometric titrations, were used to quantitatively evaluate surface charge of a suite of monodisperse nanometer sized (4, 20, and 40 nm) anatase samples in five aqueous electrolyte solutions. The electrolyte media included alkaline chloride solutions (LiCl, NaCl, KCl, and RCl) and Na-Trifluoromethanesulfonate (NaTr). Titrations were completed at 25 °C, as a function of pH (3–11) and ionic strength (from 0.005 to 0.3 m). At the molecular scale, density functional theory (DFT) simulations were used to evaluate the most stable cation surface species on the predominant (101) anatase surface. In all electrolyte media, primary charging increased with increasing particle size. At high ionic strength, the development of negative surface charge followed reverse lyotropic behavior: charge density increased in the order RbCl < KCl < NaCl < LiCl. Positive surface charge was greater in NaCl than in NaTr media. From the DFT simulations, all cations formed inner-sphere surface species, but the most stable coordination geometry varied. The specific inner-sphere adsorption geometries are dependent on the ionic radius. The experimental data were described using surface complexation modeling (SCM), constrained by the DFT results. The SCM used the charge distribution (CD) and multisite (MUSIC) models, with a two-layer (inner- and outer-Helmholtz planes) description of the electric double layer. Subtle charging differences between the smallest and larger anatase particles were the same in each electrolyte media. These results further our understanding of solid–aqueous solution interface reactivity of nanoparticles. Full article
(This article belongs to the Special Issue Mineral-Water Interfaces and Interfacial Reactions with (Radioactive) Contaminants)
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24 pages, 10366 KiB  
Article
Characteristics and Differences Analysis for Thermal Evolution of Wufeng–Longmaxi Shale, Southern Sichuan Basin, SW China
by Peixi Lyu, Jianghui Meng, Renfang Pan, Xuefei Yi, Tao Yue and Ning Zhang
Minerals 2022, 12(7), 906; https://doi.org/10.3390/min12070906 - 19 Jul 2022
Cited by 4 | Viewed by 1230
Abstract
The marine shale of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation is the main source rock and the target of shale gas exploration in the southern Sichuan Basin. The maturity of organic matter (OM) is a vital indicator for source rock evaluation. [...] Read more.
The marine shale of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation is the main source rock and the target of shale gas exploration in the southern Sichuan Basin. The maturity of organic matter (OM) is a vital indicator for source rock evaluation. Due to the lack of vitrinite, the organic matter maturity of the Wufeng–Longmaxi Formations in the southern Sichuan Basin is difficult to accurately evaluate. In total, 33 core samples of the Wufeng–Longmaxi Formations in the southern Sichuan Basin were selected to observe the optical characteristics of solid bitumen and graptolites and measure their random reflectance. Simultaneously, Raman spectroscopic parameters of kerogen were also used to quantitatively analyze the change in maturity. By using Raman spectroscopic parameters as mediators, conversion equations between graptolite random reflectance (GRor) and equivalent vitrinite reflectance (EqVRo) were established. Taking the calculation results of EqVRo as constraints, the tectono-thermal evolution history of Wufeng–Longmaxi Shale in the southern Sichuan Basin is constructed through basin modelling. The results show that the maturity of Wufeng–Longmaxi Shale in the western Changning, Luzhou-western Chongqing, eastern Changning and Weiyuan areas decreases successively. The EqVRo falls in the ranges of 3.61%~3.91%, 2.92%~3.57%, 3.08%~3.25%, 2.41%~3.12%, and the average EqVRo is 3.73%, 3.30%, 3.18% and 2.80%, respectively. Thermal evolution in western Changning was controlled by the thermal effect of the Emeishan mantle plume and paleo-burial depth, while the thermal evolution of other areas was mainly controlled by paleo-burial depth. This study provides a reliable parameter for the evaluation of thermal maturity and makes a more accurate calibration of the maturity of the Wufeng–Longmaxi Formations in the southern Sichuan Basin; it also expounds the factors for the differences in thermal evolution in different parts of the area. Full article
(This article belongs to the Special Issue Hydrocarbon Generation and Accumulation in Unconventional Shale Reservoir: Up-to-Date Advances in Theory, Experiment, Method and Application)
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25 pages, 9560 KiB  
Article
Constraints on Sandstone-Type Uranium Deposits by the Tectonic Uplift and Denudation Process in the Eastern Junggar Basin, Northwest China: Evidence from Apatite Fission Track and Detrital Zircon U-Pb Ages
by Zhangyue Liu, Suping Peng, Mingkuan Qin, Shaohua Huang, Yingying Geng and Zhongbo He
Minerals 2022, 12(7), 905; https://doi.org/10.3390/min12070905 - 19 Jul 2022
Cited by 1 | Viewed by 1672
Abstract
The uplift and denudation history of the orogenic belt and the basin–mountain coupling process have directly or indirectly affected the generation, scale, and preservation of sandstone-type uranium deposits in the eastern Junggar Basin by controlling the uranium source, lithology, facies, hydrogeology, post-generation modification, [...] Read more.
The uplift and denudation history of the orogenic belt and the basin–mountain coupling process have directly or indirectly affected the generation, scale, and preservation of sandstone-type uranium deposits in the eastern Junggar Basin by controlling the uranium source, lithology, facies, hydrogeology, post-generation modification, and other mineralization conditions. Taking the eastern Junggar Basin as the research area, this study proposes the constraints on sandstone-type uranium deposits by the tectonic uplift and denudation history of the orogenic belt in the basin using the apatite fission track (AFT), detrital zircon geochronology, and other methods. The results of the AFT age test and thermal path simulation indicate that the orogenic belt in the eastern Junggar Basin underwent four rapid uplifts; (from approximately 300 Ma to approximately 250 Ma, from approximately 130 Ma to approximately 90 Ma, from approximately 65 Ma to approximately 30 Ma, and from approximately 20 Ma to 0 Ma). Moreover, the timing of the uplift has a spatial trend of gradually becoming younger from south to north. The detrital zircon U-Pb age test showed that the sediment source area of the basin is mainly distributed in three age intervals, i.e., 460–390, 360–270, and 190–170 Ma. The comprehensive evaluation of the clastic sediment composition, stratigraphic distribution of the erosion source area, and thermal history showed that a large amount of exposed Carboniferous–Permian granites in the Qinglidi and Karameri Mountain erosion source areas contributed dominant sediment material and uranium sources for the Triassic and Middle and Lower Jurassic strata in the basin. The Ordovician–Early Devonian granites only provided sediment sources for the Upper Triassic and Lower Jurassic strata in the basin. Altay Mountain contributed some sediment sources for the Middle and Upper Jurassic strata after the magmatic activity and rapid uplift occurred in the Middle Jurassic. Based on the comprehensive analysis of the influence of the tectonic uplift process of the orogenic belt and the transformation of material source areas on uranium mineralization, the granites in the erosion source areas are proposed to contribute both external and internal uranium sources for uranium mineralization. Uranium mineralization mainly occurred in the tectonic retreat period after the rapid uplifts of the Cretaceous and Paleogene. It was terminated by the intensive uplift-induced stratigraphic deformation in the Miocene. Full article
(This article belongs to the Special Issue Geochemistry, Mineral Chemistry and Geochronology of Uranium Deposits)
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16 pages, 5679 KiB  
Article
Numerical Study on Mechanical Properties of the Freezing–Thawing Cycle of Tailings Based on Particle Discrete Element Method
by Gang Huang, Yunqin Yang, Mingyu Liu, Jianhua Zhang, Faping Liu, Akisa David Mwangi and Haiwang Ye
Minerals 2022, 12(7), 904; https://doi.org/10.3390/min12070904 - 19 Jul 2022
Cited by 1 | Viewed by 1230
Abstract
To study the effects of the number of freezing–thawing cycles (F-T cycles), the dry density, and the average particle diameter on the mechanical properties of tailings, the calibration laws of the fine-scale parameters in the discrete particle element numerical simulation software PFC2D(Particle Flow [...] Read more.
To study the effects of the number of freezing–thawing cycles (F-T cycles), the dry density, and the average particle diameter on the mechanical properties of tailings, the calibration laws of the fine-scale parameters in the discrete particle element numerical simulation software PFC2D(Particle Flow Code) were first tested, and then pre-experiments were conducted in the form of orthogonal tests. Finally, according to the results of the pre-experiments and the analysis of the pre-experimental results by SPSS (Statistical Product Service Solutions) software, uniaxial tests were carried out for different numbers of freeze–thaw cycles, different dry densities, and different average particle sizes. The tailings specimens were subjected to uniaxial compression simulations. The results showed that (1) the uniaxial compressive strength of the tailings specimens decreased with each freeze–thaw cycle, and stabilized after seven freeze–thaw cycles. (2) With a greater number of freeze–thaw actions, the porosity of the tailings increased after freeze–thawing. The peak of porosity was much higher than that of the models with fewer than seven freeze–thaw actions. (3) The contact number of tailings specimens showed a significant decrease after the number of freeze–thaw cycles reached seven. However, the amount of exposure was not the main factor affecting the strength of tailings (4). As the number of freeze–thaws increased, the tailings model was more prone to stress concentration. Previously, PFC software has been applied to tailings simulation studies, and this study verifies the feasibility of this method. This research is able to offer a reference for studying the mechanical property changes of tailings in the cold highland area. Full article
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22 pages, 9741 KiB  
Article
Timing, Provenance, and Tectonic Implications of Ore-Hosting Metasedimentary Rocks in the Giant Liba Gold Deposit, West Qinling Belt, China
by Peng-Cong Zhang, Shan-Shan Li, Bo Liu, Deng-Yang He, Quan-Sheng Cai, Germain Bishikwabo Kaningu and Xin-Chun Sun
Minerals 2022, 12(7), 903; https://doi.org/10.3390/min12070903 - 19 Jul 2022
Cited by 1 | Viewed by 1685
Abstract
The closure time of the Shangdan Ocean is critical for understanding the tectonic evolution of the Proto-Tethys Ocean. However, the proposed closure time was prolonged from Ordovician to Devonian. In the present study, detrital zircon from the metasedimentary rocks of the Liba Group [...] Read more.
The closure time of the Shangdan Ocean is critical for understanding the tectonic evolution of the Proto-Tethys Ocean. However, the proposed closure time was prolonged from Ordovician to Devonian. In the present study, detrital zircon from the metasedimentary rocks of the Liba Group in the West Qinling Belt was analyzed to constrain the closure time of the Shangdan Ocean. The three youngest grains from the Liba Group yield a maximum deposition age of 418 ± 13 Ma, indicating the Middle Devonian deposition. Detrital zircon grains show two main U–Pb age peaks of 810 Ma and 440 Ma with εHf(t) values spanning from −24.3 to +8.8 and −6.3 to +4.1, respectively, suggesting that the sediments of the Liba Group were derived from both the North and South Qinling Belts. The Lower Devonian in the South Qinling Belt shows similar provenance to the Liba Group, whereas sediments from the North Qinling Belt are absent in the Silurian strata of the South Qinling Belt. From Late Silurian to Early Devonian, the tectonic setting changed from subduction to collision. This evidence consistently suggests the disappearance of the Shangdan Ocean. The noticeable decrease in magmatism from 510–420 Ma to 420–390 Ma and the shrinking of εHf(t) values from −15.5–+12.8 to −8.4–+4.2 reveal that the Shangdan Ocean, as the eastmost embranchment of the Proto-Tethys Ocean, was closed at ca. 420 Ma. Full article
(This article belongs to the Special Issue Understanding Hydrothermal Ore Deposits: Insights from In-situ Analyses)
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3 pages, 170 KiB  
Editorial
Value of Mineralogical Monitoring for the Mining and Minerals Industry
by Uwe König and Herbert Pöllmann
Minerals 2022, 12(7), 902; https://doi.org/10.3390/min12070902 - 19 Jul 2022
Viewed by 1135
Abstract
The shift towards lower grade ore deposits, sustainable energy, CO2 reduction, volatile market conditions and digitalization has pushed the mining and minerals industry towards predictive, sustainable and agile analytical solutions to improve safety and increase operational efficiency [...] Full article
(This article belongs to the Special Issue Value of Mineralogical Monitoring for the Mining and Minerals Industry)
22 pages, 8618 KiB  
Article
Effect of the Fracturing Degree of the Source Rock on Rock Avalanche River-Blocking Behavior Based on the Coupled Eulerian-Lagrangian Technique
by Yiding Bao, Jianping Chen, Weifeng Zhang, Yuchao Li, Zhihai Li and Ni Du
Minerals 2022, 12(7), 901; https://doi.org/10.3390/min12070901 - 18 Jul 2022
Cited by 1 | Viewed by 1291
Abstract
In this study, the effect of the fracturing degree of the source rock on rock avalanche river-blocking behavior was investigated. The study included the analysis of mass movement behavior, impulse wave behavior, and the formation of landslide dams. The study included a series [...] Read more.
In this study, the effect of the fracturing degree of the source rock on rock avalanche river-blocking behavior was investigated. The study included the analysis of mass movement behavior, impulse wave behavior, and the formation of landslide dams. The study included a series of simulations of rock avalanche river-blocking based on the coupled Eulerian-Lagrangian (CEL) technique. Prior to the simulation, a water column collapse model was applied to validate the use of the CEL technique on fluid-structure interaction, and to calibrate the material parameters. The source rock in the rock avalanche simulation was cut by different groups of structural planes, with the number of 0 × 0 × 0, 1 × 1 × 1, 4 × 4 × 4, 9 × 9 × 9, 14 × 14 × 14, 19 × 19 × 19 in each dimension, respectively, to represent different fracturing degrees, on the premise of the same volume and shape of the source rock. The simulation results showed that the sliding mass exhibited structure stabilization, such that the structure of the sliding mass gradually stabilized to a steady status over time, in the mass movement process. The structure stabilization made the center of the sliding mass constantly decrease, and provided a higher speed of movement for the rock avalanches with higher fracturing degrees of the source rock. As for the impulse wave behavior, with the increase in the fracturing degree of the source rock, the maximum kinetic energy of the water decreased, and the maximum height and propagation speed of the impulse waves decreased, which indicated that the maximum height and the propagation speed of the impulse waves were positively correlated with the maximum kinetic energy of the water. In regard to the formation of the landslide dams, when the fracturing degree of the source rock was low, the shape of the landslide dam was very different. With the increase of the fracturing degree of the source rock, the shapes of the landslide dams stabilized, and varied slightly after the fracturing degree of the source rock reached a threshold value. Full article
(This article belongs to the Section Clays and Engineered Mineral Materials)
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26 pages, 4317 KiB  
Article
A Novel Approach for Resource Estimation of Highly Skewed Gold Using Machine Learning Algorithms
by M. M. Zaki, Shaojie Chen, Jicheng Zhang, Fan Feng, Aleksey A. Khoreshok, Mohamed A. Mahdy and Khalid M. Salim
Minerals 2022, 12(7), 900; https://doi.org/10.3390/min12070900 - 18 Jul 2022
Cited by 6 | Viewed by 2689
Abstract
With the complicated geology of vein deposits, their irregular and extremely skewed grade distribution, and the confined nature of gold, there is a propensity to overestimate or underestimate the ore grade. As a result, numerous estimation approaches for mineral resources have been developed. [...] Read more.
With the complicated geology of vein deposits, their irregular and extremely skewed grade distribution, and the confined nature of gold, there is a propensity to overestimate or underestimate the ore grade. As a result, numerous estimation approaches for mineral resources have been developed. It was investigated in this study by using five machine learning algorithms to estimate highly skewed gold data in the vein-type at the Quartz Ridge region, including Gaussian Process Regression (GPR), Support Vector Regression (SVR), Decision Tree Ensemble (DTE), Fully Connected Neural Network (FCNN), and K-Nearest Neighbors (K-NN). The accuracy of MLA is compared to that of geostatistical approaches, such as ordinary and indicator kriging. Significant improvements were made during data preprocessing and splitting, ensuring that MLA was estimated accurately. The data were preprocessed with two normalization methods (z-score and logarithmic) to enhance network training performance and minimize substantial differences in the dataset’s variable ranges on predictions. The samples were divided into two equal subsets using an integrated data segmentation approach based on the Marine Predators Algorithm (MPA). The ranking shows that the GPR with logarithmic normalization is the most efficient method for estimating gold grade, far outperforming kriging techniques. In this study, the key to producing a successful mineral estimate is more than just the technique. It also has to do with how the data are processed and split. Full article
(This article belongs to the Section Mineral Exploration Methods and Applications)
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18 pages, 6196 KiB  
Article
In Situ U-Pb Geochronology of Calcite from the World’s Largest Antimony Deposit at Xikuangshan, Southern China
by Junwei Xu, Xianghua Liu, Jianqing Lai, Hongsheng He, Xiangfa Song, Degao Zhai, Bin Li, Yuhua Wang, Jian Shi and Xi Zhou
Minerals 2022, 12(7), 899; https://doi.org/10.3390/min12070899 - 18 Jul 2022
Cited by 5 | Viewed by 2035
Abstract
The Xikuangshan antimony (Sb) deposit is the world’s largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first [...] Read more.
The Xikuangshan antimony (Sb) deposit is the world’s largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first LA-MC-ICP-MS U-Pb ages of syn-stibnite calcite from this deposit. The dating results indicate the presence of at least two stages of Sb mineralization in the Xikuangshan ore district. The calcite-stibnite veins in the Daocaowan ore block probably formed during the Paleocene (58.1 ± 0.9 Ma), representing an early stage of Sb mineralization, while the quartz-stibnite vein in the Feishuiyan ore block probably formed during the Eocene (50.4 ± 4.4 Ma, 50.4 ± 5.0 Ma, and 51.9 ± 1.6 Ma), representing a late stage of Sb mineralization. The new calcite U-Pb ages are significantly younger than the calcite Sm-Nd ages (124.1 ± 3.7 Ma, 155.5 ± 1.1 Ma) reported by previous researchers. We suggest that Sb mineralization of the South China antimony metallogenic belt may be related to tectono-thermal events during Paleogene, possibly linked to high heat flow during the subduction (ca. 60–40 Ma) of the Pacific Plate beneath the Eurasian Plate and/or the Indo–Asian Collision (began at ca. 61 Ma). The young in situ U-Pb ages of calcite challenge the idea of late Mesozoic Sb mineralization in the South China antimony metallogenic belt, suggesting the requirement for more high-precision dating studies. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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29 pages, 4990 KiB  
Article
Characterization and Toxicity Analysis of Lab-Created Respirable Coal Mine Dust from the Appalachians and Rocky Mountains Regions
by Vanessa Salinas, Milton Das, Quiteria Jacquez, Alexandra Camacho, Katherine Zychowski, Mark Hovingh, Alexander Medina, Gayan Rubasinghege, Mohammad Rezaee, Jonas Baltrusaitis, Neal Fairley and Pedram Roghanchi
Minerals 2022, 12(7), 898; https://doi.org/10.3390/min12070898 - 17 Jul 2022
Cited by 8 | Viewed by 2334
Abstract
Coal mine workers are continuously exposed to respirable coal mine dust (RCMD) in workplaces, causing severe lung diseases. RCMD characteristics and their relations with dust toxicity need further research to understand the adverse exposure effects to RCMD. The geographic clustering of coal workers’ [...] Read more.
Coal mine workers are continuously exposed to respirable coal mine dust (RCMD) in workplaces, causing severe lung diseases. RCMD characteristics and their relations with dust toxicity need further research to understand the adverse exposure effects to RCMD. The geographic clustering of coal workers’ pneumoconiosis (CWP) suggests that RCMD in the Appalachian region may exhibit more toxicity than other geographic regions such as the Rocky Mountains. This study investigates the RCMD characteristics and toxicity based on geographic location. Dissolution experiments in simulated lung fluids (SLFs) and in vitro responses were conducted to determine the toxicity level of samples collected from five mines in the Rocky Mountains and Appalachian regions. Dust characteristics were investigated using Fourier-transform infrared spectroscopy, scanning electron microscopy, the BET method, total microwave digestion, X-ray diffraction, and X-ray photoelectron spectroscopy. Inductively coupled plasma mass spectrometry was conducted to determine the concentration of metals dissolved in the SLFs. Finer particle sizes and higher mineral and elemental contents were found in samples from the Appalachian regions. Si, Al, Fe, Cu, Sr, and Pb were found in dissolution experiments, but no trends were found indicating higher dissolutions in the Appalachian region. In vitro studies indicated a proinflammatory response in epithelial and macrophage cells, suggesting their possible participation in pneumoconiosis and lung diseases development. Full article
(This article belongs to the Special Issue Mineralogic Analysis of Respirable Dust)
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20 pages, 13119 KiB  
Article
Mechanism of the Enrichment and Loss Progress of Deep Shale Gas: Evidence from Fracture Veins of the Wufeng–Longmaxi Formations in the Southern Sichuan Basin
by Ran Tan, Ruyue Wang, Yahao Huang, Rui Yang, Hongbo Li and Kuan Lu
Minerals 2022, 12(7), 897; https://doi.org/10.3390/min12070897 - 17 Jul 2022
Cited by 4 | Viewed by 1489
Abstract
Natural fractures caused by tectonic stress in shale can not only improve the seepage capacity of shale, but also become the migration and loss channel of free gas. Calcite, quartz and other minerals in shale fracture veins record the fluid evolution information of [...] Read more.
Natural fractures caused by tectonic stress in shale can not only improve the seepage capacity of shale, but also become the migration and loss channel of free gas. Calcite, quartz and other minerals in shale fracture veins record the fluid evolution information of the shale. Through the analysis of different types of fracture cements in the shale of the Silurian–Ordovician Wufeng–Longmaxi Formations in the southern Sichuan Basin, the effect of different fractures on shale gas construction or destruction was clarified. Geochemical investigations included the diagenetic mineral sequences in the hole–cavity veins, paleo-pressure recovery by Raman quantitative analysis, and the environments of diagenetic fluids traced by rare earth elements (REE) signatures. The density, composition, pressure, and temperature properties of CH4-bearing fluid inclusions were determined by Raman quantitative measurement and thermodynamic simulations to establish the trapping condition of the geo-fluids, and so constrain the periods of gas accumulation. The diagenetic sequences in the fracture veins can be summarized as follows: Cal-I→Qz-II→Cal-III. The Cal-I in the bedding fracture veins crystallized in the late Jurassic (~180 Ma), and originated from hydrothermal origin and diagenetic fluid; the Qz-II veins crystallized in the middle Jurassic (~190 Ma); the Cal-III veins in the high-angle fractures precipitated during the early Eocene (~12 Ma), and derived from atmospheric freshwater leaching. Pore fluid pressure gradually increased. The pressure coefficient of the shale gas reservoir gradually increased to strong overpressure from 160 Ma to 86 Ma. Between 75 Ma and the present day, the pore fluid pressure and the pressure coefficient in the shale reservoirs, having been affected by tectonic activities and strata uplift-erosion, have significantly reduced. Bedding slippage fractures play a constructive role in the enrichment of shale gas, and fracture slip can significantly improve fracture permeability. High-angle shear fractures usually cut through different strata in areas with strong tectonic activity, and destroy the sealing of the shale. The entrapment of primary methane gas inclusions recorded the process of excess reservoir pressure reduction, and indicated the partial loss of shale free gas. Full article
(This article belongs to the Special Issue Hydrocarbon Generation and Accumulation in Unconventional Shale Reservoir: Up-to-Date Advances in Theory, Experiment, Method and Application)
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12 pages, 5169 KiB  
Article
Study on Acoustic Emission and Coda Wave Characteristics of Layered Cemented Tailings Backfill under Uniaxial Compression
by Chongjie Huang, Wen He, Bokai Lu, Manman Wang, Shenhai Li and Changbo Xiao
Minerals 2022, 12(7), 896; https://doi.org/10.3390/min12070896 - 17 Jul 2022
Cited by 5 | Viewed by 1138
Abstract
The paper analyzes the effects of filling times and filling interval time on the acoustic emission characteristics and coda wave characteristics of layered cemented tailings backfill under uniaxial compression and, to a certain extent, enriches the study of layered cemented tailings backfill in [...] Read more.
The paper analyzes the effects of filling times and filling interval time on the acoustic emission characteristics and coda wave characteristics of layered cemented tailings backfill under uniaxial compression and, to a certain extent, enriches the study of layered cemented tailings backfill in this field. The work aims to monitor the early warning of layered cemented tailings backfill with different layering factors during deformation and damage by the changing law of acoustic emission and ultrasonic signals. By conducting uniaxial compression tests, acoustic emission, and ultrasonic tests of layered cemented tailings backfill, the acoustic emission parameters and their fractal characteristics of layered cemented tailings backfill with different layering factors during uniaxial compression were calculated. Meanwhile, the variation law of the coda wave velocity variation rate of layered cemented tailings backfill during uniaxial loading was analyzed using coda wave interferometry. The test results show the feasibility of using acoustic emission and ultrasonic means to monitor and warn about the deformation damage of layered cemented tailings backfill. Full article
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17 pages, 1599 KiB  
Article
Mineral Neutralizers as a Tool for Improving the Properties of Soil Contaminated with Copper
by Andrzej Cezary Żołnowski and Mirosław Wyszkowski
Minerals 2022, 12(7), 895; https://doi.org/10.3390/min12070895 - 17 Jul 2022
Cited by 5 | Viewed by 1668
Abstract
In phytoremediation processes implemented in highly contaminated areas, there is a high risk of contaminant toxicity during the germination of freshly sown plants. In such conditions, it is recommended to support phytoremediation by using neutralizing additives. The present study aimed at assessing the [...] Read more.
In phytoremediation processes implemented in highly contaminated areas, there is a high risk of contaminant toxicity during the germination of freshly sown plants. In such conditions, it is recommended to support phytoremediation by using neutralizing additives. The present study aimed at assessing the effect of the addition of mineral neutralizers (MNs), i.e., limestone, clay, and zeolite, to soil contaminated with copper (0, 200, 400, 600 mg kg−1). Basic soil indicators were analyzed, such as pH, hydrolytic acidity (HAC), total exchangeable bases (TEB), cation exchange capacity (CEC), base saturation (BS), electrolytical conductivity (EC), total organic carbon (TOC), total nitrogen (Ntot), carbon to nitrogen ratio (C:N),, and interactions of soil micronutrients, such as Cu, Zn, Cd, Cr, Ni, Pb, Mn, and Fe with MNs. Copper contamination significantly decreased the soil pH and increased its HAC. A decrease in the share of TEB was found, which resulted in a decrease in the CEC and in BS of the soil. Among the additives, limestone had the most beneficial effect on reducing soil acidity, contributing to a significant increase in TEB, CEC, and BS. The least favorable effect was shown for clay, which generally caused the deterioration of soil properties. The MNs significantly increased the content of Zn, Cr, and Fe and lowered the content of Ni in the soil compared to the control. The demonstrated interactions indicate the diversified activity of MNs at different levels of soil contamination with copper. Full article
(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)
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12 pages, 3140 KiB  
Article
Chemical and Spectral Variations between Untreated and Heat-Treated Rubies from Mozambique and Madagascar
by Qi Lu, Xinyi Li, Lihua Sun and Binrong Qin
Minerals 2022, 12(7), 894; https://doi.org/10.3390/min12070894 - 16 Jul 2022
Cited by 2 | Viewed by 1909
Abstract
The chemical composition and spectra of untreated and heat-treated rubies from Mozambique and Madagascar were analyzed by an electron probe microscopy analysis, laser ablation inductively coupled plasma quadrupole mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-visible spectroscopy. Due to the different [...] Read more.
The chemical composition and spectra of untreated and heat-treated rubies from Mozambique and Madagascar were analyzed by an electron probe microscopy analysis, laser ablation inductively coupled plasma quadrupole mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-visible spectroscopy. Due to the different content of Fe and different inclusions, rubies from Madagascar belong to alkaline basalt deposit, while rubies from Mozambique belong to amphibole metamorphic rock. The ruby samples were heated to 900 °C to change their color. As Fe and Ti ions can be transferred into different valences and diffused into the interior of rubies, Cr ions in cracks or cleavages entered the crystal lattice during heat treatment and the content of Fe and Ti decreased, while the content of Cr increased in heat-treated rubies. After heating, blue-purple decreased and the red hue increased, while the blue color band disappeared and yellow appeared in the cracks of the samples because of the chemical changes. Compared with untreated rubies, the infrared absorption peaks of 2123 cm−1 and 1990 cm−1 related to inclusions disappeared, and the existence of 3236 cm−1 and 3186 cm−1 absorption peaks was a typical characteristic of heat-treated ruby, which was produced by changes in its inclusion. In addition, due to the weakened charge transfer of Fe2+ and Ti4+ and the increasing reaction of Fe2+ → Fe3+ along with the heat treatment, the UV-visible absorption peak at 400 nm shifted to purple. Full article
(This article belongs to the Special Issue Gems and Gem Minerals)
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23 pages, 5156 KiB  
Article
The Volcanic-Rich Layer of the “Camporotondo (Marche, Italy)” Section: Petrography and Sedimentation of an Unknown Distal Messinian Eruption
by Davide Potere, Vittorio Scisciani, Monica Piochi, Pietro Paolo Pierantoni, Angela Mormone, Manuela Nazzari, Piergiorgio Scarlato and Gianluca Iezzi
Minerals 2022, 12(7), 893; https://doi.org/10.3390/min12070893 - 16 Jul 2022
Cited by 2 | Viewed by 1445
Abstract
A Messinian and lithified horizon enriched in volcanic particles with thicknesses of 170–180 cm crops in the Camporotondo (CR) section (Marche, Italy). This volcanic-rich layer (VRL) was investigated by field plus mesoscopic observations, X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), bulk composition [...] Read more.
A Messinian and lithified horizon enriched in volcanic particles with thicknesses of 170–180 cm crops in the Camporotondo (CR) section (Marche, Italy). This volcanic-rich layer (VRL) was investigated by field plus mesoscopic observations, X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), bulk composition methods and electron-microprobe analysis (EMPA). The quantitative textural features of volcanic and sedimentary components were determined by 2D image analysis. The lowermost massive 70–80 cm portion is free of sedimentary structure or characterised only by plane-parallel ones, whereas the uppermost one is undulated and cross-laminated. The XRPD and SEM outcomes unveil that the VRL of CR is mainly composed of glassy shards (≥80 area%), a variable amount of sedimentary minerals (<20 area%) and a very low content of magmatic minerals (few area%). The bulk and micro-chemical attributes of volcanic and glassy materials are rhyolitic and almost identical to previous VRLs dated at 5.5 Ma (VRL-5.5). The signatures of immobile elements and the high amount of H2O present in the glass fraction suggest a provenance from a convergent geodynamic setting. The 2D image analysis on SEM observations show that the VRL-5.5 of CR is composed of very fine and sorted (averages of MZ of 5,72 and σi of 0,70), scarcely vesicular, glass shards, with similar long and short size dimensions, shape and roundness. The VRL-5.5 of CR is free of large minerals and fossils. The coupling of mesoscopic and microscopic determinations indicates that the lowermost interval was deposited such as a primary tephra, i.e., fallout pyroclasts sinking in seawater. Instead, the uppermost interval derives from local, low-energy and sin-depositional remobilisation of the same VRL-5.5. The textural attributes of the volcanic fractions, the sedimentological features and the thickness of the VRL at CR correspond to the westward deposit of a still unknown eruption likely occurred at 5.5 Ma. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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24 pages, 6395 KiB  
Article
Geochronology, Whole-Rock Geochemistry, and Sr–Nd–Hf Isotopes of Granitoids in the Tongshanling Ore Field, South China: Insights into Cu and W Metallogenic Specificity
by Yuyu Tang, Hua Kong, Biao Liu, Qi Zong, Qianhong Wu, Hua Jiang and Fucheng Tan
Minerals 2022, 12(7), 892; https://doi.org/10.3390/min12070892 - 15 Jul 2022
Cited by 2 | Viewed by 1613
Abstract
The Qin-Hang Metallogenic Belt (QHMB), an important metallogenic belt in South China, hosts Cu and W–Sn polymetallic deposits. The Tongshanling ore field in the QHMB is characterized by the coexistence of Cu- and W-bearing polymetallic deposits, which are related to granodiorite and granite [...] Read more.
The Qin-Hang Metallogenic Belt (QHMB), an important metallogenic belt in South China, hosts Cu and W–Sn polymetallic deposits. The Tongshanling ore field in the QHMB is characterized by the coexistence of Cu- and W-bearing polymetallic deposits, which are related to granodiorite and granite porphyry. This study examined whole-rock geochemistry, geochronology, and Sr–Nd–Hf isotopes to determine the genetic relationship between diverse ore-related granitoids (i.e., granodiorite and granite porphyry) and Cu–W metallogeny in the Tongshanling ore field. Zircon LA-ICP-MS U–Pb dating shows that the granodiorite and granite porphyry in the Tongshanling ore field were emplaced at 163.7 ± 0.4 Ma to 154.7 ± 0.6 Ma and 161.1 ± 0.3 Ma, respectively. Geochemically, the granodiorites are classified as oxidized I-type, while the highly evolved granite porphyry is reduced A-type. The Lu–Hf isotopic composition of the granodiorites is characterized by εHf(t) values ranging from –10.49 to –4.99 (average = –7.17), with corresponding TDMC ages ranging from 1524 to 1877 Ma (average = 1682 Ma). In contrast, the granite porphyry has higher εHf(t) values (–3.60 to –1.58, average = –2.78) and younger TDMC (1310–1438 Ma, average = 1387 Ma). The εNd(t) values of granodiorite are −8.06 to −7.37 and the two-stage model ages (TDM2) are 1543–1598 Ma, while the granite porphyry has higher εNd(t) values (−3.0 to −3.4) and younger TDM2 ages (1195–1223 Ma). The results show that the granodiorite and granite porphyry were formed from partial melting of different Mesoproterozoic basement rocks under varying degrees of crust–mantle interaction. Granite porphyry underwent well-recorded fractional crystallization. Compared to the Cu-forming granodiorite, the W-forming granite porphyry has a higher differentiation index, higher crystallization temperatures of zircon (average = 708 °C versus 631 °C), and lower oxygen fugacity (median ΔFMQ = –2.21 versus –1.77). Full article
(This article belongs to the Special Issue Mineralogy, Geochemistry and Geochronology of W-Sn Polymetallic Deposits)
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11 pages, 2362 KiB  
Article
Low-Temperature Flotation Separation of Diaspore from Kaolinite by Using a Mixed Collector
by Xiaofei Man, Chenliang Wang, Shichao Yu, Xiaofeng Yang, Jianjun Liu, Yafeng Fu, Zhenhai Dong, Hui Zhi and Leming Ou
Minerals 2022, 12(7), 891; https://doi.org/10.3390/min12070891 - 15 Jul 2022
Cited by 1 | Viewed by 1214
Abstract
In this paper, the effect of a new mixed collector sodium oleate (NaOl)/tert dodecyl mercaptan (TDM) on the separation of diaspore and kaolinite at 283 K was investigated. The molar ratio of NaOl to TDM is 8:2. The properties of the mixed collector [...] Read more.
In this paper, the effect of a new mixed collector sodium oleate (NaOl)/tert dodecyl mercaptan (TDM) on the separation of diaspore and kaolinite at 283 K was investigated. The molar ratio of NaOl to TDM is 8:2. The properties of the mixed collector and its adsorption mechanism on diaspore and kaolinite were studied by surface tension measurements, Zeta potential determinations and XPS analysis. The flotation results show that the mixed collector NaOl/TDM has a good collection ability for diaspore and a good selectivity for kaolinite at low temperatures. Therefore, the mixed collector NaOl/TDM can effectively separate diaspore and kaolinite under alkaline conditions at 283 K. The results of surface tension measurements show that the molecular density, hydrophobic association ability and collection ability of the mixed collector NaOl/TDM are better than those of the single collector at 283 K. In addition, the formation of a micelle effect of the mixed collector NaOl/TDM has a synergistic effect, which improves the reagent activity at low temperatures with the flotation effect enhanced. The results of the Zeta potential determinations and XPS analysis show that the total adsorption capacity of the mixed collector NaOl/TDM on the surface of the diaspore at low temperatures is higher than that of NaOl, and the adsorption capacity on the surface of kaolinite is similar to that of NaOl. The mixed collector NaOl/TDM may be adsorbed on the surface of diaspore and kaolinite by a hydrogen bond at 283 K. Full article
(This article belongs to the Special Issue Progress of Reagents in Minerals Flotation)
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16 pages, 5690 KiB  
Article
The Test Flight of iFTEM-I Fixed-Wing Airborne Time-Domain Electromagnetic System in Binxian, Heilongjiang Province, China
by Hongshan Zheng, Junfeng Li, Wei Huang, Yu Liu, Fei Li, Qingmin Meng, Qingquan Zhi, Xingchun Wang and Ning Lu
Minerals 2022, 12(7), 890; https://doi.org/10.3390/min12070890 - 15 Jul 2022
Viewed by 1352
Abstract
The fixed-wing time-domain airborne electromagnetic method (FTEM) has been widely used in metal mining exploration, groundwater mapping and other fields worldwide, and in recent decades, its use has gradually also become more prevalent in China. The first generation of the fixed-wing time-domain airborne [...] Read more.
The fixed-wing time-domain airborne electromagnetic method (FTEM) has been widely used in metal mining exploration, groundwater mapping and other fields worldwide, and in recent decades, its use has gradually also become more prevalent in China. The first generation of the fixed-wing time-domain airborne electromagnetic system (iFTEM-I), researched and developed by the Institute of Geophysical and Geochemical Exploration (IGGE), has been demonstrated in recent years. In this article, we introduce the brief working principle and system parameters of iFTEM-I, and we show that the effective prospecting depth of iFTEM-I is up to 350 m, which is indicated by a comparison of the results between iFTEM-I and a ground TEM system (TEM-30B) carried out in Binxian. Full article
(This article belongs to the Special Issue New Methods and Technologies for Mineral Geological and Geophysical Exploration in China)
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64 pages, 28625 KiB  
Review
Practical Experience of Filtered Tailings Technology in Chile and Peru: An Environmentally Friendly Solution
by Carlos Cacciuttolo Vargas and Giovene Pérez Campomanes
Minerals 2022, 12(7), 889; https://doi.org/10.3390/min12070889 - 15 Jul 2022
Cited by 16 | Viewed by 8859
Abstract
In the last 20 years many mining projects around the world have applied a tailings deposition technology named “dry stacking of filtered tailings” at tailings storage facilities (TSFs). This technique produces an unsaturated cake that allows storing this material without the need to [...] Read more.
In the last 20 years many mining projects around the world have applied a tailings deposition technology named “dry stacking of filtered tailings” at tailings storage facilities (TSFs). This technique produces an unsaturated cake that allows storing this material without the need to manage large slurry tailings ponds. The application of this technology has accomplished: (i) an increase in tailings water recovery, (ii) a reduction of the TSF footprint (impacted areas), and (iii) a decrease in the risk of physical instability, being TSFs self-supporting structures under compaction (such as dry stacks), and (iv) a better regulator and community perception satisfying the need of stable TSFs. This paper presents the main features, benefits, and advances in filtered tailings technology applied in Chile and Peru with emphasis on: (i) filtering technology evolution over the last decade: description of main equipment, advantages, and disadvantages, (ii) design considerations for main TSF geometrical configurations, tailings transport and placement systems, TSF water management, TSF operational and emergency plans, and TSF progressive closure, (iii) operation experiences at site-specific conditions, (iv) technology acceptance in regulatory frameworks, (v) lessons learned and advances, and (vi) new trends and future developments, considering technical, environmental, regulatory frameworks and cost-effective manners. Full article
(This article belongs to the Special Issue Tailings Dams: Design, Characterization, Monitoring, and Risk Assessment)
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16 pages, 4666 KiB  
Article
A Quantitative Relationship between Oxidation Index and Chalcopyrite Flotation Recovery
by Xu Yang, Yubiao Li, Wen Chen, Wanqing Duan, Qing Xiao and Tingting Jiang
Minerals 2022, 12(7), 888; https://doi.org/10.3390/min12070888 - 15 Jul 2022
Cited by 1 | Viewed by 1399
Abstract
The surface oxidation of chalcopyrite is one of the most important factors affecting its flotation performance. In this study, a critical oxidation degree is proposed to define “slight” and “significant” oxidation in terms of surface species and chalcopyrite flotation recovery. Slight oxidation enhanced [...] Read more.
The surface oxidation of chalcopyrite is one of the most important factors affecting its flotation performance. In this study, a critical oxidation degree is proposed to define “slight” and “significant” oxidation in terms of surface species and chalcopyrite flotation recovery. Slight oxidation enhanced chalcopyrite hydrophobicity, but significant oxidation reduced its recovery apparently. Microthermokinetic measurements indicated that the apparent activation energy (Ea) of chalcopyrite oxidation was reduced from around 173 kJ·mol−1 to 163 kJ·mol−1 when the reaction changed from slight oxidation to significant oxidation when applying H2O2. The surface oxidation degree was defined as the ratio of hydrophilic species to hydrophobic species. The highest recovery (94.8%) and contact angle (93°) were achieved at a concentration of 0.1 vol.% H2O2, with the lowest oxidation degree of 0.388 being observed. The oxidation degree was correlated to the flotation recovery, with a quantitative relationship (y = −298.81x + 213.05, y and x represent flotation recovery and oxidation degree, respectively, 0.388 ≤ x ≤ 0.618) being established, thereby giving a guideline to better manage chalcopyrite flotation by controlling its surface oxidation and SBX adsorption on chalcopyrite surfaces. Full article
(This article belongs to the Special Issue Seawater Flotation)
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