Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (80)

Search Parameters:
Keywords = hydrothermal regime

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
18 pages, 2421 KiB  
Review
Frictional Experiments on Granitic Faults: New Insights into Continental Earthquakes and Micromechanical Mechanisms
by Huiru Lei, Shimin Liu and Wenhao Dai
Appl. Sci. 2025, 15(13), 7207; https://doi.org/10.3390/app15137207 - 26 Jun 2025
Viewed by 306
Abstract
Granitic faults within the crystalline upper-to-middle continental crust play a critical role in accommodating tectonic deformation and controlling earthquake nucleation. To better understand their frictional behavior, we review experimental studies conducted under both dry and hydrothermal conditions using velocity-stepping (VS), constant-velocity (CV), and [...] Read more.
Granitic faults within the crystalline upper-to-middle continental crust play a critical role in accommodating tectonic deformation and controlling earthquake nucleation. To better understand their frictional behavior, we review experimental studies conducted under both dry and hydrothermal conditions using velocity-stepping (VS), constant-velocity (CV), and slide-hold-slide (SHS) tests. These approaches allow the quantification of frictional strength, velocity dependence, and healing behavior across a range of conditions. Our synthesis highlights that the friction coefficient of granite gouges decreases with increasing temperature and pore fluid pressure, decreasing slip velocity, and increasing slip displacement. The velocity-weakening regime shifts to higher temperatures with increasing slip velocity or decreasing pore fluid pressure. Temperature, normal stress, pore fluid pressure, and slip velocity interact to modulate frictional stability. In particular, microstructural observations reveal that grain size reduction, pressure solution creep, and fluid-assisted chemical processes are key mechanisms governing transitions between velocity-weakening and velocity-strengthening regimes. These insights support the growing application of microphysical-based models, which integrate micromechanical processes and offer improved extrapolation from the laboratory to natural fault systems compared to classical rate-and-state friction laws. The collective evidence underscores the importance of considering fault rheology in a temperature- and fluid-sensitive context, with implications for interpreting seismic cycle behavior in continental regions. Full article
Show Figures

Figure 1

44 pages, 10740 KiB  
Article
Fluid Evolution in the Bundelkhand Granite, North Central India: Implications for Hydrothermal Activities in the Bundelkhand Craton
by Duttanjali Rout, Jayanta K. Pati, Terrence P. Mernagh and Mruganka K. Panigrahi
Minerals 2025, 15(6), 579; https://doi.org/10.3390/min15060579 - 29 May 2025
Viewed by 412
Abstract
The Bundelkhand granite (BG) constitutes the bulk of the granitoid complex in the Bundelkhand Craton and preserves imprints of its evolution from the magmatic to a protracted hydrothermal stage as deduced from the petrography. In order to reconstruct such a path of evolution [...] Read more.
The Bundelkhand granite (BG) constitutes the bulk of the granitoid complex in the Bundelkhand Craton and preserves imprints of its evolution from the magmatic to a protracted hydrothermal stage as deduced from the petrography. In order to reconstruct such a path of evolution in this study, thermobarometric calculations were attempted on the mineral chemistry of the major (hornblende, plagioclase, biotite) and minor (epidote, apatite) magmatic phases. They yielded magmatic temperatures and pressures (in excess of 700 °C and ~5 kbar), although not consistently, and indicate mid-crustal conditions at the onset of crystallization. Temperatures in the hydrothermal regime within the BG are better constrained by the chemistry of the chlorite and epidote minerals (340 to 160 °C) that conform with the ranges of homogenization temperatures of aqueous–biphase inclusions in matrix quartz in the BG and subordinate quartz veins. These reconstructions indicate that fluid within the BG evolved down to lower temperatures and towards the deposition of quartz and, more importantly, bears a striking similarity to the temperature–salinity characteristics of fluid in the giant quartz reef system. Scanty mixed aqueous–carbonic inclusions in the BG are indicative of the CO2-poor nature of the BG magma and the exsolution of CO2 at lower pressure (~2.6 kbar). The dominant mechanism of fluid evolution in the BG appears to be the incursion of meteoric fluid, which caused fluid dilution. Laser Raman microspectrometry reveals many types of solid phases in aqueous–carbonic inclusions in the BG domain. The occurrence of unusual, effervescent-type inclusions, though infrequent, bears a striking similarity to that reported in the giant quartz reef domain. Thus, the highlight of the present work is the convincing fluid inclusion evidence that genetically links the BG with the giant quartz reef system, although many cited discrepancies arise from the radiometric dates. We visualize the episodic release of silica-transporting fluid to the major fracture system (now occupied by the giant reef) from the BG, thus making the fluid in the two domains virtually indistinguishable. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
Show Figures

Figure 1

19 pages, 11465 KiB  
Article
Scots Pine at Its Southern Range in Siberia: A Combined Drought and Fire Influence on Tree Vigor, Growth, and Regeneration
by Viacheslav I. Kharuk, Il’ya A. Petrov, Alexander S. Shushpanov, Sergei T. Im and Sergei O. Ondar
Forests 2025, 16(5), 819; https://doi.org/10.3390/f16050819 - 14 May 2025
Viewed by 439
Abstract
Climate models have predicted changes in woody plant growth, vitality, and species distribution. Those changes are expected mainly within the boundaries of species ranges. We studied the influence of changing hydrothermal and burning-rate regimes on relict pine stands at the southern edge of [...] Read more.
Climate models have predicted changes in woody plant growth, vitality, and species distribution. Those changes are expected mainly within the boundaries of species ranges. We studied the influence of changing hydrothermal and burning-rate regimes on relict pine stands at the southern edge of the Pinus sylvestris range in Siberia. We hypothesize that (1) warming has stimulated pine growth under conditions of sufficient moisture supply, and (2) increased burning rate has threatened forest viability. We found that the increase in air temperature, combined with the decrease in soil and air drought, stimulated tree growth. Since the “warming restart” around 2000, the growth index (GI) of pines has exceeded its historical value by 1.4 times. The GI strongly correlates with the GPP and NPP of pine stands (r = 0.82). Despite the increased fire rate, the GPP/NPP and EVI index of both pine stands and surrounding bush–steppes are increasing, i.e., the pine habitat is “greening” since the warming restart. These results support the prediction (by climatic scenarios SSP4.5, SSP7.0, and SSP8.5) of improvement in tree habitat in the Siberian South. Meanwhile, warming has led to a reduction in the fire-return interval (up to 3–5 y). Although the post-fire density of seedlings on burns (ca. 10,000 per ha) is potentially sufficient for pine forest recovery, repeated surface fires have eliminated the majority of the undergrowth and afforestation. In a changing climate, the preservation of relict pine forests depends on a combination of moisture supply, burning rate, and fire suppression. Full article
(This article belongs to the Section Forest Ecology and Management)
Show Figures

Figure 1

36 pages, 9140 KiB  
Article
The Geochemical Characteristics of Ore-Forming Fluids in the Jebel Stah Fluorite Deposit in Northeast Tunisia: Insights from LA-ICP-MS and Sr Isotope Analyses
by Chaima Somrani, Fouad Souissi, Radhia Souissi, Giovanni De Giudici, Eduardo Ferreira da Silva, Dario Fancello, Francesca Podda, José Francisco Santos, Tamer Abu-Alam, Sara Ribeiro and Fernando Rocha
Minerals 2025, 15(4), 331; https://doi.org/10.3390/min15040331 - 21 Mar 2025
Cited by 1 | Viewed by 1126
Abstract
The Zaghouan Fluorite Province (ZFP) encloses F-Ba(Pb-Zn) ores hosted within Jurassic carbonate series, in northeastern Tunisia. Critical breakthroughs on the Jebel Stah fluorite deposits, an MVT-style F-mineralization, have been made within the Lower Jurassic limestones along the Zaghouan Fault, which is a major [...] Read more.
The Zaghouan Fluorite Province (ZFP) encloses F-Ba(Pb-Zn) ores hosted within Jurassic carbonate series, in northeastern Tunisia. Critical breakthroughs on the Jebel Stah fluorite deposits, an MVT-style F-mineralization, have been made within the Lower Jurassic limestones along the Zaghouan Fault, which is a major target for mineralization. This study presents the first REE-Y analyses conducted by LA-ICP-MS on fluorites in Tunisia, and specifically on the fluorites of Jebel Stah deposit. This analytical technique provides highly accurate insights into the geochemical regime of mineralizing fluids and the related scavenging sources. Distinct geochemical characteristics between two fluorite generations (G1 and G2) were revealed. Fluorites (Fl2) from the early generation (G1) showed low ΣREE + Y (36.3 and 39.73 ppm, respectively). When normalized to chondrites, early fluorite G1 displayed a bell-shaped REE + Y pattern with a depletion in LREE relative to HREE and a slight MREE hump. Late fluorite (Fl3) generation (G2) displayed higher ΣREE + Y concentrations (77.43 ppm), but an almost similar REE pattern. Ce/Ce* ratios demonstrated strong negative Ce anomalies in all fluorites, while Eu/Eu* ratios indicated weak negative Eu anomalies. The positive Y anomaly observed in the REE + Y patterns of fluorites G1 and G2 suggests Y-Ho fractionation in the fluid system. Moreover, significant degrees of differentiation between terbium (Tb) and lanthanum (La) have been observed in all fluorite samples. The plot of fluorites from both fluorite generations on the Tb/La–Tb/Ca diagram gives evidence of the sedimentary hydrothermal origin of the ore-forming fluids in the Jebel Stah F-deposit. Sr isotopes show that the mineralizing fluids are radiogenic and deeply sourced basinal brines, whereas the small variation in 87Sr/86Sr ratios suggests a similar source for Sr in fluorites G1 and G2. These results allow us to conclude that the economic fluorite (G1) ore of Jebel Stah was deposited due to the interaction of the deeply sourced hydrothermal fluid with the carbonated host rocks (dolomitization, an increase in pH, and Ca activity), whereas the late fluorite (G2) is an accessory and could have resulted from the mixing of the hydrothermal fluid with shallow meteoric waters. Full article
Show Figures

Figure 1

23 pages, 5418 KiB  
Article
Modeling of CO2 Efflux from Forest and Grassland Soils Depending on Weather Conditions
by Sergey Kivalov, Irina Kurganova, Sergey Bykhovets, Dmitriy Khoroshaev, Valentin Lopes de Gerenyu, Yiping Wu, Tatiana Myakshina, Yakov Kuzyakov and Irina Priputina
Soil Syst. 2025, 9(1), 25; https://doi.org/10.3390/soilsystems9010025 - 6 Mar 2025
Viewed by 830
Abstract
Carbon dioxide (CO2) efflux from soil (or soil respiration, SR) is one of the most important yet variable characteristics of soil. When evaluating large areas, CO2 efflux modeling serves as a viable alternative to direct measurements. This research aims to [...] Read more.
Carbon dioxide (CO2) efflux from soil (or soil respiration, SR) is one of the most important yet variable characteristics of soil. When evaluating large areas, CO2 efflux modeling serves as a viable alternative to direct measurements. This research aims to identify site-specific differences and their effects on empirical CO2 efflux modeling. The experimental data from 25 years of field observations were utilized to identify the optimal site- and weather-specific models, parameterized for normal, wet, and dry years, for the forest and grassland ecosystems located on similar Entic Podzols (Arenic) in the same bioclimatic coniferous–deciduous forest zone. The following parameters were considered in the examined models: mean monthly soil or air temperatures (Tsoil and Tair), amount of precipitation during the current (P) and the previous (PP) months, and the storage of soil organic carbon (SOC) in the top 20 cm of soil. The weighted non-linear regression method was employed to estimate the model parameters for the normal, wet, and dry years. To increase the magnitude of the model resolutions, we controlled the slope and intercept of the linear model comparison between the measured and modeled data through the change in R0—CO2 efflux at Tsoil = 0 °C. The mean bias error (MBE), root-mean-square error (RMSE), and determination coefficient (R2) were employed to assess the quality of the model’s performance. The measured Tsoil, Tair, and P, as well as the litter (for forest) or sod (for grassland) horizon (modeled by the Soil SCLmate Statistical Simulator (SCLISS)), and soil temperatures (Tlit_m, Tsoil_m) and moistures (Mlit_m, Msoil_m), were used for SR simulation. For the CO2 efflux in the forest ecosystem with the lower SOC availability for mineralization, the direct Tsoil and Tair measurements in combination with SOC storage provided better parameterization for the empirical TPPC model. For the CO2 efflux in the grassland ecosystem with the high SOC availability for mineralization, the temperature became the governing factor, and the TPPrh model provided better performance over all the considered models. The model’s performance was the best for the wet years, and the worst for the dry years for both ecosystems. For forest ecosystems, the model performance for average precipitation years was equivalent to that in wet years. For grassland ecosystems, however, the model performance was equivalent to that in dry years due to differing exposure and hydrothermal regimes. The wet-year R0 obtained for both forest and grassland ecosystems differed from the normal- and dry-year values. The measured SR values relevant for the R0 estimations distribute along the precipitation range for the forest and along the temperature range for the grassland. The SCLISS-modeled Tlit_m and Mlit_m provide good alternatives to direct atmospheric measurements, and can be used as initial temperature and moisture data for CO2 efflux modeling when direct soil and moisture observations are not available on site. Full article
Show Figures

Figure 1

12 pages, 11964 KiB  
Article
Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability
by Yuequn Tao and Zhiqiang Zhu
Nanomaterials 2025, 15(4), 306; https://doi.org/10.3390/nano15040306 - 17 Feb 2025
Viewed by 834
Abstract
Previous research has studied the evolution of patterns during the evaporation of sessile droplets of pure liquid, although there is a lack of reports focusing on the transition of flow regimes and flow stability of nanofluids. In this study, we investigate the evaporation [...] Read more.
Previous research has studied the evolution of patterns during the evaporation of sessile droplets of pure liquid, although there is a lack of reports focusing on the transition of flow regimes and flow stability of nanofluids. In this study, we investigate the evaporation of sessile droplets of Al2O3-ethanol nanofluid to elucidate the dynamic characteristics of the evaporation process from the perspective of internal convection. As the temperature increases, internal convection intensifies, significantly accelerating the evaporation rate. Three distinct convection flow patterns are observed under the combined influence of the Marangoni effect and buoyancy during evaporation: initially, two macroscopic convection cells form, followed by the periodic generation and propagation of hydrothermal waves (HTWs) near the contact line. Subsequently, Bénard–Marangoni (BM) convection cells gradually emerge and ultimately dominate the flow dynamics. The deposition patterns, which differ in part from the classic coffee-ring pattern, are closely related to the flow patterns of HTWs and BM convection cells during the pinning stage of droplet evaporation. Furthermore, the critical Marangoni (Ma) and Rayleigh (Ra) numbers for the onset of convection flow instability increase with rising substrate heating temperature. Full article
Show Figures

Figure 1

22 pages, 29178 KiB  
Article
Molybdenite Re–Os and Zircon U–Pb Isotopic Constraints on Gold Mineralization Associated with Fine-Grained Granite in the Xiawolong Deposit, Jiaodong Peninsula, East China
by Mingchao Wu, Zhongliang Wang and Pengyu Liu
Appl. Sci. 2025, 15(3), 1199; https://doi.org/10.3390/app15031199 - 24 Jan 2025
Viewed by 733
Abstract
Molybdenite Re–Os and zircon U–Pb isotopic data are first obtained from the stockwork and disseminated-style gold-bearing ores and the fine-grained granite hosting these ores in the Xiawolong gold mine, respectively, which is located within the Muping–Rushan gold metallogenic belt, eastern Jiaodong Peninsula, so [...] Read more.
Molybdenite Re–Os and zircon U–Pb isotopic data are first obtained from the stockwork and disseminated-style gold-bearing ores and the fine-grained granite hosting these ores in the Xiawolong gold mine, respectively, which is located within the Muping–Rushan gold metallogenic belt, eastern Jiaodong Peninsula, so as to illustrate the genesis of gold mineralization and its implication for exploration. Four molybdenite samples yield a well-defined Re–Os isochron age of 118.4 ± 2.5 Ma (2σ), which is identical to the weighted average Re–Os model age of 118 ± 1.7 Ma (2σ). Integration of the new geochronologic data with those reported recently from the other gold mines in the Muping–Rushan gold metallogenic belt suggests that a discrete gold event occurred in Xiawolong ca. 4 m.y. older than that for the other gold mineralization at ca. 114 Ma in eastern Jiaodong. In addition, two fine-grained granite samples, measured using the LA-ICP-MS zircon U–Pb method, produce the first precise ages of 118 ± 2 to 117 ± 2 Ma (2σ), identical to the molybdenite Re–Os ages, within the margin of error and obtained in this study. The fine-grained granite has a similar lithology and emplacement age as those of the medium-grained monzogranite consisting of the marginal facies of the Sanfoshan batholith, and is considered to be the crystallization products of Sanfoshan granitic magma in the late stage. Combined with the previous S-Pb-D-O isotope, fluid inclusion and geological studies, which suggest that the ore-forming fluid of Xiawolong gold mineralization is from magmatic water, and the identification that the magnetite coexists with the gold-bearing pyrite and molybdenite in the gold ores, which indicates a high oxygen fugacity (fO2) of both the magma and resultant hydrothermal fluids, it is logical to infer that the Xiawolong gold deposit is genetically in relation to the Sanfoshan granitic magmatism, which is high in fO2 and rich in Au at the magmatic–hydrothermal transition stage, and the change in fO2 mostly likely makes a significant contribution to the precipitation of Au. This result reveals that the late-stage granitic magma with high fO2, which is crystallized into the fine-grained granite, probably is also rich in Au, except the W–Mo–Cu–Zn–U–Be–Li–Nb–Ta–Sn–Bi-elements. Therefore, based on the extensional tectonic regime for the early Cretaceous Jiaodong gold deposits, we propose that gold exploration in the Jiaodong should not only focus on the fault-hosted Au but also on the fine-grained granite-hosted Au around the apical portions of the late Early Cretaceous small-granitic intrusions with high fO2. This model could also be important for prospecting in other gold ore districts, which have a similar tectonic setting. Full article
(This article belongs to the Special Issue Technologies and Methods for Exploitation of Geological Resources)
Show Figures

Figure 1

20 pages, 11775 KiB  
Article
Mulching Practice Regulates the Soil Hydrothermal Regime to Improve Crop Productivity in the Rainfed Agroecosystem of the Loess Plateau in China
by Fanxiang Han, Yuanhong Zhang, Lei Chang, Yuwei Chai, Zhengyu Bao, Hongbo Cheng, Shouxi Chai, Fangguo Chang, Guohua Chang and Ruiqi Yang
Agriculture 2025, 15(1), 76; https://doi.org/10.3390/agriculture15010076 - 31 Dec 2024
Viewed by 801
Abstract
Mulching practices have demonstrated the potential to increase crop yields and resource utilization efficiency. However, the response of different crops with various growth stages to different mulching practices remains unclear, particularly in the rainfed agroecosystem. Therefore, a two-year field experiment (2013–2015) of different [...] Read more.
Mulching practices have demonstrated the potential to increase crop yields and resource utilization efficiency. However, the response of different crops with various growth stages to different mulching practices remains unclear, particularly in the rainfed agroecosystem. Therefore, a two-year field experiment (2013–2015) of different crops (wheat, maize, and potato) was conducted to evaluate the effects of three different mulching treatments: straw strip mulching (SM), plastic film mulching (PM), and conventional planting without mulching as the control (CK), on soil moisture and temperature, evapotranspiration (ET), water use efficiency (WUE), crop yield and economic benefits on the Loess Plateau. The results indicated that both mulching practices significantly increased the soil water content (SM: 4.3% and PM: 3.6%) compared to CK. However, the effects on soil temperature varied between mulching practices, PM increased soil temperature by 4.9% compared to CK, while SM decreased it by 6.3%. The improved soil hydrothermal conditions, characterized by favorable temperatures and higher soil water status would lead to a higher crop daily growth rate (5.3–49.8%), as well as greater dry matter accumulation (4.7–36.7%). Furthermore, mulching practice (SM and PM) has a significant influence on crop yield and its components of various crops, as well as WUE. The mean grain yield of SM and PM was, respectively, increased by 11.4% and 27.1% for winter wheat, compared to CK, 1.8% and 24.3% for spring maize, and 23.0% and 13.9% for potato, respectively. Compared to CK, PM yielded a higher net economic benefit and WUE for winter wheat and spring maize, while SM presented the best economic benefit and WUE for potato. In conclusion, a comprehensive analysis of crop yield, economic benefits, and resource utilization efficiency suggests that straw strip mulching for potato is a more sustainable environmentally friendly mulching practice, recommended for rainfed farming systems on the Loess Plateau and areas with similar climatic conditions. Full article
Show Figures

Figure 1

30 pages, 7429 KiB  
Article
Isotope Geochemistry and Metallogenic Model of the Bailugou Vein-Type Zn-Pb-Ag Deposit, Eastern Qinling Orogen, China
by Yan Yang, Hui Chen, Nana Guo, Donghao Wu, Zhenshan Pang and Yanjing Chen
Minerals 2024, 14(12), 1244; https://doi.org/10.3390/min14121244 - 6 Dec 2024
Cited by 1 | Viewed by 897
Abstract
The large-scale vein-type Zn-Pb-Ag deposit in the Eastern Qinling Orogen (EQO) has sparked a long-standing debate over whether magmatism or metamorphism was the primary control or factor in its formation. Among the region’s vein-type deposits, the large-sized Bailugou deposit offers a unique opportunity [...] Read more.
The large-scale vein-type Zn-Pb-Ag deposit in the Eastern Qinling Orogen (EQO) has sparked a long-standing debate over whether magmatism or metamorphism was the primary control or factor in its formation. Among the region’s vein-type deposits, the large-sized Bailugou deposit offers a unique opportunity to study this style of mineralization. Similar to other deposits in the area, the vein-type orebodies of the Bailugou deposit are hosted in dolomitic marbles (carbonate–shale–chert association, CSC) of the Mesoproterozoic Guandaokou Group. Faults control the distribution of the Bailugou deposit but do not show apparent spatial links to the regional Yanshanian granitic porphyry. This study conducted comprehensive H–O–C–S–Pb isotopic analyses to constrain the sources of the ore-forming metals and metal endowments of the Bailugou deposit. The δ34SCDT values of sulfides range from 1.1‰ to 9.1‰ with an average of 4.0‰, indicating that the sulfur generated from homogenization during the high-temperature source acted on host sediments. The Pb isotopic compositions obtained from 31 sulfide samples reveal that the lead originated from the host sediments rather than from the Mesozoic granitic intrusions. The results indicate that the metals for the Bailugou deposit were jointly sourced from host sediments of the Mid-Late Proterozoic Meiyaogou Fm. and the Nannihu Fm. of the Luanchuan Group and Guandaokou Group, as well as lower crust and mantle materials. The isotopic composition of carbon, hydrogen, and oxygen collectively indicate that the metallogenic constituents of the Bailugou deposit were contributed by ore-bearing surrounding rocks, lower crust, and mantle materials. In summary, the study presents a composite geologic-metallogenic model suggesting that the Bailugou mineral system, along with other lead-zinc-silver deposits, porphyry-skarn molybdenum-tungsten deposits, and the small granitic intrusions in the Luanchuan area, are all products of contemporaneous hydrothermal diagenetic mineralization. This mineralization event transpired during a continental collision regime between the Yangtze and the North China Block (including syn- to post-collisional settings), particularly during the transition from collisional compression to extension around 140 Ma. The Bailugou lead-zinc-silver mineralization resembles an orogenic-type deposit formed by metamorphic fluid during the Yanshanian Orogeny. Full article
Show Figures

Figure 1

21 pages, 21536 KiB  
Review
A Review on Uranium Mineralization Related to Na-Metasomatism: Indian and International Examples
by Priyanka Mishra, Manju Sati and Rajagopal Krishnamurthi
Geosciences 2024, 14(11), 304; https://doi.org/10.3390/geosciences14110304 - 12 Nov 2024
Cited by 2 | Viewed by 1652
Abstract
Uranium mineralization related to Na-metasomatism is known as Na-metasomatite or albitite-type. They represent the fourth-largest uranium resource globally and constitute fifty thousand tons of U resources. The present work gives details about well-known Na-metasomatic uranium occurrences worldwide in terms of structures, metasomatic stages, [...] Read more.
Uranium mineralization related to Na-metasomatism is known as Na-metasomatite or albitite-type. They represent the fourth-largest uranium resource globally and constitute fifty thousand tons of U resources. The present work gives details about well-known Na-metasomatic uranium occurrences worldwide in terms of structures, metasomatic stages, geochemical characteristics, fluid inclusions, and compositions of stable isotopes. The host rocks are granite, granitoid, and metamorphosed volcano-sedimentary rocks, and these rocks experienced two/three deformational stages. U mineralization is mainly confined to faults and characterized by granitic intrusive, cataclasis, mylonitization, and albitization. The albitized rocks exhibit two to three metasomatic and late hydrothermal stages. The first stage is marked by the replacement of pre-existing host minerals during a ductile shear regime. The second stage is related to U mineralization contemporaneous with the brittle deformation. The albitized rocks exhibit depletion in Si, K, Ba, and heavy rare-earth elements relative to the host rocks and enrichments in Na, Ca, U, Zr, P, V, Sr, and light rare-earth elements. U-enrichment is positively correlated with Na, Mo, Cu, and high-field strength elements. The pressure–temperature (P-T) conditions of U mineralization are considered to be epithermal and mesothermal. Fluid inclusion studies indicate that the mineralizing fluids were rich in Na+, Mg2+, Cl, CO2, H2O, F, and PO43− and meteoric–magmatic derived. The geological processes responsible for the genesis of Na-metasomatic U deposits of the North Delhi Fold Belt (India) are comparable with some international examples, i.e., Australia, Ukraine, Cameroon, Brazil, Guyana, China, and the USA. Full article
(This article belongs to the Section Geochemistry)
Show Figures

Figure 1

20 pages, 12111 KiB  
Article
Effects of Curing Regimes on Calcium Oxide–Belite–Calcium Sulfoaluminate-Based Aerated Concrete
by Yanqing Xia, Xirui Lu, Jun Li, Li Yang, Ning Wang, Xuemei Chen and Wen Zhong
Materials 2024, 17(19), 4819; https://doi.org/10.3390/ma17194819 - 30 Sep 2024
Viewed by 1057
Abstract
This study delves into the effects of carbonation curing and autoclave–carbonation curing on the properties of calcium oxide–belite–calcium sulfoaluminate (CBSAC) cementitious material aerated concrete. The objective is to produce aerated concrete that adheres to the strength index in the Chinese standard GB/T 11968 [...] Read more.
This study delves into the effects of carbonation curing and autoclave–carbonation curing on the properties of calcium oxide–belite–calcium sulfoaluminate (CBSAC) cementitious material aerated concrete. The objective is to produce aerated concrete that adheres to the strength index in the Chinese standard GB/T 11968 while simultaneously mitigating CO2 emissions from cement factories. Results show that the compressive strength of CBSAC aerated concrete with different curing regimes (autoclave curing, carbonation curing, and autoclave–carbonation curing) can reach 4.3, 0.8, and 4.1 MPa, respectively. In autoclave–carbonation curing, delaying CO2 injection allows for better CO2 diffusion and reaction within the pores, increases the carbonation degree from 19.1% to 55.1%, and the bulk density from 603.7 kg/m3 to 640.2 kg/m3. Additionally, microstructural analysis reveals that delaying the injection of CO2 minimally disrupts internal hydrothermal synthesis, along with the formation of calcium carbonate clusters and needle-like silica gels, leading to a higher pore wall density. The industrial implementation of autoclavecarbonation curing results in CBSAC aerated concrete with a CO2 sequestration capacity ranging from 40 to 60 kg/m3 and a compressive strength spanning from 3.6 to 4.2 MPa. This innovative approach effectively mitigates the carbon emission pressures faced by CBSAC manufacturers. Full article
Show Figures

Figure 1

18 pages, 2454 KiB  
Article
Mantle Volatiles and Heat Contributions to the Cu-Pb-Zn Mineralization in the Baoshan Deposit, South China: Constraints from He and Ar Isotopes
by Jinchuan Huang, Jiantang Peng and Tengxiang Xie
Minerals 2024, 14(8), 839; https://doi.org/10.3390/min14080839 - 19 Aug 2024
Viewed by 1161
Abstract
The Baoshan deposit is one of the important Cu-Pb-Zn deposits associated with granitic rocks in the Nanling Range, South China. Here, we present He and Ar isotope data for the Baoshan deposit to decipher the contributions of mantle-derived volatiles and heat to its [...] Read more.
The Baoshan deposit is one of the important Cu-Pb-Zn deposits associated with granitic rocks in the Nanling Range, South China. Here, we present He and Ar isotope data for the Baoshan deposit to decipher the contributions of mantle-derived volatiles and heat to its Cu-Pb-Zn mineralization. The ore-forming fluids in sphalerite and pyrite exhibited 3He/4He ratios up to 1.51 Ra. A linear correlation between He and Ar isotopes suggests that the ore-forming fluids were a mixture of a predominantly mantle-derived fluid with a high 3He/4He ratio and a shallow crustal fluid, characterized by a low 3He/4He ratio. The δ34S values of sulfides in the Baoshan deposit ranged from +2.30 to +5.21‰, consistent with the magma-derived sulfur. The calculated 3He/Q ratios for the ore-forming fluid exceeded those of mid-oceanic ridge hydrothermal solutions by 10 to 50 times, indicating that the ore-forming fluids acquired both heat and volatiles in a convective hydrothermal regime rather than a conductive one. Therefore, there is a significant contribution of mantle-derived volatiles, heat, and possibly metals, to the Cu-Pb-Zn mineralization in the Baoshan deposit, and the continuous influx of mantle-derived fluids/melts probably plays a crucial role during the Cu-Pb-Zn mineralization related to granitic rocks. Full article
Show Figures

Figure 1

15 pages, 2511 KiB  
Article
An Interseasonal Comparison of Soil Respiration in Xeric and Mesic Pine Forest Ecosystems in Central Siberia
by Anastasia Makhnykina, Eugene Vaganov, Alexey Panov, Daria Polosukhina and Anatoly Prokushkin
Atmosphere 2024, 15(8), 988; https://doi.org/10.3390/atmos15080988 - 17 Aug 2024
Cited by 2 | Viewed by 1111
Abstract
An understanding of how boreal forest composition responds to global environmental changes is an important challenge to predicting the future global carbon balance. Boreal forests are the most significant sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to ongoing [...] Read more.
An understanding of how boreal forest composition responds to global environmental changes is an important challenge to predicting the future global carbon balance. Boreal forests are the most significant sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to ongoing climate changes. The combination of the hydrothermal conditions of a territory strongly regulates its biogeochemical processes. The carbon fluxes in boreal forests are strongly mediated by the ground vegetation cover, composed of mosses (mesic) and lichens (xeric). Despite the concurrence of xeric and mesic vegetation types, their responses to climate variations varies significantly. Soil emission is an informative indicator of ecosystem functioning. In this study, we focused on the soil CO2 dynamics during frost-free seasons with different precipitation regimes in the xeric and mesic boreal ecosystems of Central Siberia. Seasonal measurements of soil CO2 emissions were conducted during frost-free seasons using the dynamic chamber method. Our findings reveal that the precipitation regimes of each year may control the seasonal soil emission dynamics. The soil moisture is the most important driver of emissions growth in the water-limited lichen pine forest (R2adj. = 18%). The soil temperature plays the largest role in the feather moss pine forest during the dry (R2adj. = 31%) seasons, and in the lichen pine forest during the wet (R2adj. = 41%) seasons. The cumulative efflux for the xeric and mesic sites is mostly related to the hydrothermal conditions, and not to the differences in ground vegetation cover. During the dry seasons, on average, the soil CO2 emissions are 45% lower than during the wet seasons for both sites. These findings emphasize the need for estimating and including the hydrothermal characteristics of the growing season for detailed emission assessments. Full article
(This article belongs to the Section Biosphere/Hydrosphere/Land–Atmosphere Interactions)
Show Figures

Figure 1

38 pages, 22170 KiB  
Article
New Geochemical and Geochronological Constraints on the Genesis of the Imourkhssen Cu±Mo±Au±Ag Porphyry Deposit (Ouzellagh-Siroua Salient, Anti-Atlas, Morocco): Geodynamic and Metallogenic Implications
by Mariam Ferraq, Saïd Belkacim, Li-Zhen Cheng, Joshua H. F. L. Davies, Morgann G. Perrot, Abdelhay Ben-Tami and Mohammed Bouabdellah
Minerals 2024, 14(8), 832; https://doi.org/10.3390/min14080832 - 16 Aug 2024
Cited by 3 | Viewed by 2161
Abstract
The Imourkhssen porphyry Cu±Mo±Au±Ag deposit is located at the Ouzellagh-Siroua Salient (OSS) straddling the boundary between the central Anti-Atlas and the central High Atlas. It is characterized by a typical porphyry-style mineralization. The volcanic rocks are intruded by numerous magmatic rocks of the [...] Read more.
The Imourkhssen porphyry Cu±Mo±Au±Ag deposit is located at the Ouzellagh-Siroua Salient (OSS) straddling the boundary between the central Anti-Atlas and the central High Atlas. It is characterized by a typical porphyry-style mineralization. The volcanic rocks are intruded by numerous magmatic rocks of the Ouarzazate Group (580–539 Ma), referred to as the Late Ediacaran magmatic suites (LEMS). Of these, the Askaoun, Imourkhssen, and Imourgane granites are the most significant as they are related to the porphyry mineralization. The entire set is intruded by the Zaghar mafic dyke swarms. Zircon U-Pb dating of the Imourkhssen granite and the ore-bearing granite porphyry shows that these intrusive rocks were emplaced at 558 ± 1 and 550 ± 2 Ma, respectively. Moreover, the whole-rock major and trace element geochemistry reveal a high-K calc-alkaline I-type composition, consistent with an emplacement in a post-collisional setting under a trans-tensional tectonic regime. Ore bodies are hosted by the Askaoun granodiorite as well as the Imourgane granite. The mineralization occurs as fine-grained dissemination and infills of hydrothermally altered NNE–SSW to N–S trending veins and veinlets. Ore-related hydrothermal alteration consists of potassic, chlorite-sericite, serecitic, and propylitic mineral assemblages along with pervasive silicification and pyritization, providing a porphyry-style alteration pattern. The ore periods comprise supergene and magmatic-hydrothermal periods. The latter includes primary dissemination and secondary NNE–SSW to N–S ore-bearing system stages. The occurrence of molybdenite is either restricted to the potassic and chlorite-sericite alteration zones of the ore-bearing granite as fine disseminations or alternatively as veinlet infills within the propylitic halos. The molybdenite occurrences along with pyrite, chalcopyrite, galena, and tennantite dissemination are assigned to the primary ore stage, while the NNE–SSW to N–S ore-bearing system is related to the secondary ore stage. It consists of pyrite, chalcopyrite, bornite, covellite, diagenite, sphalerite, hematite, galena, gold, and chenguodaite. The predominance of cockade and crack-and-seal textures suggest multiple episodes of ore-forming fluid circulations under epithermal conditions. The supergene stage is achieved by subordinate malachite, azurite, barite, hematite, epsomite, and chrysocolla. From the descriptions above, we argue that the Imourkhssen Cu±Mo±Au±Ag mineralization shares many mineralogical and paragenetic attributes of porphyry-copper deposits. Full article
(This article belongs to the Special Issue Igneous Rocks and Related Mineral Deposits)
Show Figures

Figure 1

51 pages, 12244 KiB  
Article
Mineralogy and Origin of Vein Wolframite Mineralization from the Pohled Quarry, Havlíčkův Brod Ore District, Czech Republic: Interaction of Magmatic and Basinal Fluids
by Zdeněk Dolníček, Jana Ulmanová, Luboš Vrtiška, Karel Malý, Michaela Krejčí Kotlánová and Rostislav Koutňák
Minerals 2024, 14(6), 610; https://doi.org/10.3390/min14060610 - 14 Jun 2024
Cited by 2 | Viewed by 1751
Abstract
Mineralogy and formation conditions were studied in a newly found vein wolframite mineralization, cutting migmatitized paragneisses in the exocontact of a small Carboniferous granite body in the Pohled quarry, Moldanubian Zone of the Bohemian Massif, Czech Republic. The early stage of the rich [...] Read more.
Mineralogy and formation conditions were studied in a newly found vein wolframite mineralization, cutting migmatitized paragneisses in the exocontact of a small Carboniferous granite body in the Pohled quarry, Moldanubian Zone of the Bohemian Massif, Czech Republic. The early stage of the rich mineral assemblage (36 mineral species) involves wolframite, columbite-group minerals, molybdenite, and scheelite hosted by quartz–muscovite–chlorite gangue, which was followed by base-metal sulfides in a quartz gangue, whereas the last stage included calcite gangue with fluorite and minor sulfides. The mineral assemblage points to the mobility of usually hardly soluble elements, including W, Sn, Zr, Nb, Th, Ti, Sc, Y, and REEs. A fluid inclusion study indicates a significant decrease in homogenization temperatures from 350–370 °C to less than 100 °C during vein formation. Fluids were aqueous, with a low salinity (0–12 wt. % NaCl eq.) and traces of CO2, N2, CH4, H2, and C2H6. The δ18O values of the fluids giving rise to quartz and scheelite are positive (min. 4‰–6‰ V-SMOW). The Eh and pH of the fluid also changed during evolution of the vein. Both wolframite and columbite-group minerals are anomalously enriched in Mg. We suggest that the origin of this distinct mineralization was related to the mixing of Mo,W-bearing granite-derived magmatic fluids with external basinal waters derived from contemporaneous freshwater (but episodically evaporated) piedmont basins. The basinal waters infiltrated into the subsurface along fractures formed in the extensional tectonic regime, and their circulation continued even after the ending of the activity of magmatic fluids. The studied wolframite mineralization represents the most complete record of the ‘hydrothermal’ history of a site adjacent to a cooling granite body in the study area. Moreover, there are broad similarities in the mineral assemblages, textures, and chemical compositions of individual minerals from other occurrences of wolframite mineralization around the Central Moldanubian Plutonic Complex, pointing to the genetic similarities of the Variscan wolframite-bearing veins in this area. Full article
Show Figures

Graphical abstract

Back to TopTop