Enhanced silicate weathering(ESW)is a geoengineering method aimed at accelerating carbon dioxide(CO_(2))removal(CDR)from atmosphere by increasing the weathering flux of silicate rocks and minerals.It has emerged as a ...Enhanced silicate weathering(ESW)is a geoengineering method aimed at accelerating carbon dioxide(CO_(2))removal(CDR)from atmosphere by increasing the weathering flux of silicate rocks and minerals.It has emerged as a promising strategy for CDR.Theoretical studies underscore ESW’s substantial potential for CDR and its diverse benefits for crops when applied to croplands.However,the well-known significant discrepancies in silicate weathering rates between laboratory and field conditions introduce uncertainty in CDR through ESW.By compiling data from recent literature,we calculated and compared CDR efficiency(t CO_(2)t^(-1)_(silicate)ha^(-1)y^(-1))observed in mesocosm experiments and field trials.The findings indicate that CDR efficiencies in field trials are comparable to or exceeding that observed in mesocosm experiments by 1-3 orders of magnitude,particularly evident with wollastonite application.The hierarchy of CDR efficiency among silicates suitable for ESW is ranked as follows:olivine≥wollastonite>basalt>albite≥anorthite.We suggest the potential role of biota,especially fungi,in contributing to higher CDR efficiencies observed in field trials compared to mesocosm experiments.We further emphasize introducing fungi known for their effectiveness in silicate weathering could potentially enhance CDR efficiency through ESW in croplands.But before implementing fungal-facilitated ESW,three key questions need addressing:(i)How does the community of introduced fungi evolve over time?(ii)What is the long-term trajectory of CDR efficiency following fungal introduction?and(iii)Could fungal introduction lead to organic matter oxidation,resulting in elevated CO_(2)emissions?These investigations are crucial for optimizing the efficiency and sustainability of fungal-facilitated ESW strategy.展开更多
Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to ...Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to comprehending the developmental history and future trends of black soil,especially against the background of large-scale global cultivation and climate change.Although the importance of black soil formation and evolution cannot be ignored,the relevant research is still very scarce.In this study,a typical eight-meter-deep soil core was collected from the Keshan area of the Songnen Plain,Northeast China,where surface black soil developed on paleo-sediments.Using^(14)C dating,the formation age of the black soil was determined.Based on the characteristics of the geochemical composition,grain size and the magnetic susceptibility of the sediments,it was demonstrated that the black soil and its parent material originated from reworked loess.Furthermore,the mass transfer coefficient(τ)of some elements was determined,in order to explore the soil weathering process.By calculating the transported amount of alkaline and alkaline-earth elements,the weathering rate of parent material to black soil was found to be weak,at 0.16 kEq·ha^(-1)·year^(-1).Combining the results of dating and carbon density in the different layers of black soil,the accumulation rate of organic carbon was determined as follows:rapidly increasing in the initial period of 13.2-2.2 ka,reaching its maximum average value of 34.0 g·cm^(-2)·a^(-1)at 2.2-0.8 ka,then showing a decreasing trend with an average value of-77.5 g·cm^(-2)·a^(-1).Compared with regional climate change,Keshan black soil has developed under a colder and wetter climate during the Holocene.Predictably,ongoing global warming may lead to the degradation of black soils in the Songnen Plain,as well as in other regions.Our results will enrich geological knowledge of black soil formation and future evolutionary trends.展开更多
Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before...Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before the formation of stable rust layers,weathering steel is prone to liquid rust sagging and spattering,leading to environmental pollution and city appearance concerns.These factors limit the application and development of weathering steel.In this study,a rapid and environmentally friendly method was de-veloped by introducing alloying elements,specifically investigating the role of Sn in the rapid stabilization of rust layers in marine atmo-spheric environments.The rust layer formed on weathering low-alloy steel exposed to prolonged outdoor conditions and laboratory im-mersion experiments was explored using electron probe micro-analyzer(EPMA),micro-Raman,X-ray photoelectron spectroscopy(XPS),and electrochemical measurements.Results showed an optimal synergistic effect between Sn and Cr,which facilitated the accelerated densification of the rust layer.This beneficial effect enhanced the capability of the rust layer to resist Cl^(-)erosion and improved the protec-tion performance of the rust layer.展开更多
Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,i...Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.展开更多
Dry-wet cycle is a key factor in surface weathering of earthen heritage,which remains insufficiently explained.It involves the interaction of humidity,stress,and damage.Using the RFPA(realistic failure process analysi...Dry-wet cycle is a key factor in surface weathering of earthen heritage,which remains insufficiently explained.It involves the interaction of humidity,stress,and damage.Using the RFPA(realistic failure process analysis)numerical method,this study reproduced the processes of humidity diffusion,deformation,stress,and damage evolution under dry-wet cycles in the soil site of Suoyang City,China.The numerical results indicate that the drying phase following rainfall has the most significant deteriorative impact on the earthen heritage.The evaporation of surface moisture during this phase causes volume shrinkage,which in turn generates tensile stress and leads to the formation of numerous desiccation cracks.Desiccation cracks provide channels for moisture diffusion,which further exacerbates generation of the cracks,leading to a mutual promotion between the two phenomena.Furthermore,during the wetting phase,the model elements undergo hygroscopic expansion,resulting in a slight increase in strain and displacement.Previously formed cracks may exhibit temporary narrowing or closure,but will revert during the subsequent drying phase.Ultimately,the overall displacement increases with the number of dry-wet cycles.The findings provide a theoretical foundation for protection against surface weathering and other damage in earthen heritage in arid regions.展开更多
Silicon(Si)is an important element in aquatic ecosystems.Based on the observed data in the Huanghe(Yellow)River Basin,a forward model was used to evaluate the silicate weathering rate in the Huanghe River Basin.The ef...Silicon(Si)is an important element in aquatic ecosystems.Based on the observed data in the Huanghe(Yellow)River Basin,a forward model was used to evaluate the silicate weathering rate in the Huanghe River Basin.The effects of silicate weathering,damming,and land use change on the Si concentration and flux were analyzed.Results show that the dissolved Si(DSi)concentration decreased first and then increased,and was 0.82–2.96 mg/L.As a silicon source in the Huanghe River Basin,the silicate weathering rate in the upper reaches of Lanzhou was high,and a large amount of DSi was transported to the lower reaches.Agricultural irrigation in the middle reaches caused a large amount of DSi loss,and the interception of large-scale cascade reservoirs caused a large amount of DSi retention.The DSi released by sediment re-suspension due to high runoff scouring in the downstream channel also served as a silicon source to supplement the DSi flux transported to the sea.Suspended particulate matter and biogenic Si(BSi)increased first and then decreased in the ranges of 24.1–1590.7 mg/L and 0.08–2.17 mg/L,respectively,due mainly to severe soil erosion in the eastern Loess Plateau,which caused significant amounts of phytoliths to enter the water.展开更多
Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and op...Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and open sea environments.The research focused on a cost-eff ective ex situ experiment to examine the eff ects of EW reaction pathways arising from the interactions among rock powder,seawater and CO_(2).The experimental fi ltrates from diff erent milled peridotite samples exhibit a decrease in the Mg/Ca ratio as the specifi c surface area increases,which accelerates reaction rates.This suggests that the leached Mg from the original rock may have been consumed in the formation of brucite,serpentine and carbonates during EW.Similar reaction pathways are also responsible for the chemical alterations observed in amphibolite,albeit to varying degrees.On the other hand,the experimental residues showed an increase in loss on ignition compared to the original rock,indicating that EW has facilitated the incorporation of H 2 O and CO_(2) into secondary mineral structures through various reaction pathways,leading to the formation of brucite,serpentine and carbonates.Thermal gravimetric analysis of the experimental residues confi rms the presence of these minerals based on their decomposition temperatures.Additionally,XRD analysis identifi ed a range of carbonates in the residues of both peridotite and amphibolite samples,validating the occurrence of carbonation reactions.SEM images reveal textural changes in both samples,supporting the formation of secondary minerals through EW,consistent with observations from the petrographic study of untreated samples.Control experiments on CO_(2) absorption in seawater showed a decrease in pH,highlighting ocean acidifi cation from increased CO_(2) emissions.However,when rock powder was added to the seawater-CO_(2) mixture,the pH increased.This suggests that the EW of ultramafi c rock powders can sequester CO_(2) while raising seawater pH through the formation of secondary minerals.This research could serve as an analog for EW applications,considering the worldwide abundance of ultramafi c rocks and the availability of coastal and open ocean environments.However,further research is required to understand the behavior of other elements and their impacts on ocean chemistry in EW processes before applying CO_(2) sequestration strategies.展开更多
A micro-layered structure was observed in the stable rust layer through dry–wet cycle corrosion tests.The microstructure,element distribution,and corrosion resistance mechanism of this layer structure in the marine i...A micro-layered structure was observed in the stable rust layer through dry–wet cycle corrosion tests.The microstructure,element distribution,and corrosion resistance mechanism of this layer structure in the marine industrial atmosphere were investigated by focused ion beam–scanning electron microscopy and high-resolution transmission electron microscopy.The inner rust layer of weathering steel(WS)exhibited layered enrichment of Cr,Cu,Ti,and other alloying elements.This layered structure comprised a fully amorphous region rich in Cr and Ti,as well as an amorphous and nanocrystalline region rich in Fe but poor in Cr.Only the completely amorphous region of the inner rust layer demonstrated a strong adsorption effect on Cl^(−).Cr-rich amorphous region played a pivotal role in reducing the corrosion of WS in the marine industrial atmospheric environment.The interface between the amorphous and nanocrystalline regions,as well as cracks within the interlayer,facilitated Cl^(−)transport,while the intact interlayer effectively hindered HSO_(3)^(−).展开更多
Rock classification plays a crucial role in various fields such as geology,engineering,and environmental studies.Employing deep learning AI(artificial intelligence)methods has a high potential to significantly improve...Rock classification plays a crucial role in various fields such as geology,engineering,and environmental studies.Employing deep learning AI(artificial intelligence)methods has a high potential to significantly improve the accuracy and efficiency of this task.The paper delves into the exploration of two cuttingedge AI techniques,namely Mask DINO and Mask R-CNN(convolutional neural network),as means to identify rock weathering grades and rock types.The results demonstrate that Mask DINO,which is a Detection Transformer(DETR),outperforms Mask R-CNN for the aforementioned purposes.Mask DINO achieved f-1 scores of 91% and 86% in weathering grade detection and rock type detection,as opposed to the Mask R-CNN's f-1 scores of 84% and 75%,respectively.These findings underscore the substantial potential of employing DETR algorithms like Mask DINO for automatic classification of both rock type and weathering states.Although the study examines only two AI models,the data processing and other techniques developed in this study may serve as a foundation for future advancements in the field.By incorporating these advanced AI techniques,logging personnel can obtain valuable references to aid their work,ultimately contributing to the advancement of geological and related fields.展开更多
Carbonic acid produced by the dissolution of atmospheric and soil CO_(2)in water is usually the most dominant catalyst for chemical weathering,but a sulfuric aciddriven phenomenon,different from usual,was found in the...Carbonic acid produced by the dissolution of atmospheric and soil CO_(2)in water is usually the most dominant catalyst for chemical weathering,but a sulfuric aciddriven phenomenon,different from usual,was found in the orogenic belt watersheds dominated by silicate bedrock.This study,rooted in comprehensive field investigations in the Manas River Basin(MRB)north of the Tianshan Mountains,delves into the mechanisms and impacts of sulfuric and carbonic acid as catalysts driving diff erent types of chemical weathering in the Central Asian Orogenic Belt.Quantitative analyses elucidate that carbonate weathering constitutes 52.4%of the total chemical weathering,while silicate and evaporite account for 18.6%and 25.3%,respectively,with anthropogenic activities and atmospheric precipitation having little eff ect.The estimated total chemical weathering rate in MRB is approximately 0.075×10^(6)mol/km^(2)/year.Quantitative findings further suggest that,preceding carbonate precipitation(<10^(4)year),chemical weathering can absorb CO_(2).Subsequently,and following carbonate precipitation(10^(4)-10^(7)year),it will release CO_(2).The release significantly surpasses the global average CO_(2)consumption,contributing to a noteworthy climate impact.This study underscores the distinctive weathering mechanisms,wherein sulfuric acid emerges as the predominant catalyst.The quantity of sulfuric acid as a catalyst is approximately three times that of carbonic acid.Sulfuric acid-driven carbonate rock weathering(SCW)is identified as the sole chemical weathering type with a net CO_(2)release eff ect.SCW CO_(2)release flux(5176 mol/km^(2)/year)is roughly 2.5 times the CO_(2)absorption by Ca-Mg silicate weathering,highlighting the pivotal role of chemical weathering in sourcing atmospheric CO_(2)over the timescales of carbonate precipitation and sulfate reduction.Lastly,this study posits that catalyst and transport limitations are the most plausible critical factors in MRB.The interplay between sulfuric acid and dissolved CO_(2)competitively shapes the types and rates of chemical weathering reactions.展开更多
Exploring the relationship between weathering and erosion is essential for understanding the evolution of landscapes and formation of soil under the influence of climate, tectonics, and topography. We measured the bul...Exploring the relationship between weathering and erosion is essential for understanding the evolution of landscapes and formation of soil under the influence of climate, tectonics, and topography. We measured the bulk chemistry of regoliths and calculated their weathering rates and intensity in three locations in China: Inner Mongolia in the mid-temperate semi-humid zone; Jiangxi Province, in the mid-subtropical humid zone; and Hainan Province, in the tropical humid zone. These profiles exhibited increased weathering with increasing temperature and precipitation.The low-gradient profile exhibited stronger weathering of saprolite than of soil, whereas the high-gradient profile showed a more constant weathering pattern. The regolith in the cold climate was the product of easily weatherable minerals, whereas weathering of K-feldspar and even secondary minerals occurred in hot and humid climates. The weathering of subtropical profiles was both supply-and kinetic-limited, controlled by weathering and erosion. The tropical profile experienced supply-limited weathering,indicating slow erosion and an intense weathering profile;the mid-temperate profile was not classifiable due to weak erosion and weathering. Long-term weathering fluxes of these profiles show that Si, Na, and K(or Mg) represent thebulk of the mass lost through weathering. This study underscores that weathering of granitic regolith is controlled by both climatic conditions and landscape.展开更多
Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mec...Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mechanical properties of the composites before and after UV accelerated weathering. HDPE, wood fibers, pigments and other processing additives were dry-mixed in a high-speed mixer. The mixtures were extruded by two-step extrusion process with a self-designed twin-screw/single-screw extruder system. Color of the samples was determined according to CIE 1976 L^＊a^＊b^＊ system by a spec- trophotometer and the bending properties were tested to evaluate the mechanical properties before and after accelerated UV weathering. The result shows that the modulus of elasticity of WF/HDPE did not obvi- ously changed after incorporating with the pigments, but the bending strength increased. After accelerated aging for 2000 h, both color and mechanical properties significantly changed. Iron oxide red and black performed better than the other two pigments, and the pigments dosage of 2.28% in the composites is favourable.展开更多
Rice-hull powder is widely used in manufacturing reinforced plastic composites.However,its weathering ability is rarely considered.We studied the performance of two types of rice-hull-polyethylene（RH-PE） composites ...Rice-hull powder is widely used in manufacturing reinforced plastic composites.However,its weathering ability is rarely considered.We studied the performance of two types of rice-hull-polyethylene（RH-PE） composites after they were exposed outdoor to natural weathering for two years.The samples did not change in bending strength and elasticity modulus.At the end of the testing period,colour lightness had increased by more than 23% and total colour had changed by more than 9 units.This means the colour evidently differentiate from the original colour that the customers choose.The analyses of Fourier-transform infrared（FTIR） and X-ray photoelectron spectroscopy（XPS） showed that oxidation had occurred on sample surfaces.Red lumber presented an obvious C=O peak after weathering,while yellow lumber did not present an obvious peak as evidence of oxidation.Both types of lumbers showed a reduction of lignocellulosic groups and amorphous regions of PE.展开更多
Cavernous weathering is commonly found on sandstone slopes in different environments. Either a single dominant process or polygenetic agents require to be invoked in order to interpret the development. The Yongningsha...Cavernous weathering is commonly found on sandstone slopes in different environments. Either a single dominant process or polygenetic agents require to be invoked in order to interpret the development. The Yongningshan hill of the central Loess Plateau is representative of cliff dwellings in Northwest China, which is characterized by well-developed cavernous weathering features and provides a good opportunity for the better understanding of sandstone weathering in the Loess Plateau. Multiple methods, including field survey, in-situ rock strength measurement, along with experiments on samples for microscopic observation, element composition and salt chemistry, were employed to investigate the controlling factors of cavernous weathering. The results show that cavern development is different on the four slopes with the western slope hosting massive honeycombs, tafoni and hardened surfaces. The porous and permeable aeolian sandstones are fundamental, because they provide space and pathways for the transportation of water and salt, honeycombs dominantly aligning within the lamination of cross-beds. The environmental factors such as the seasonal wetting and drying cycle, aeolian salt, moisture and water vapor are key factors for the development of cavernous weathering forms. The northern and northwestern wind-blown dust storms have brought abundant salts, the lengthier dry periods of the wetting and drying cycle being beneficial for salt accumulation within caverns, favoring salt weathering.展开更多
As the dominant macrofauna in many soils,earthworms play a significant role in mineral weathering and nutrient release from mineral structures into available forms for root uptake.Phlogopite is a trioctahedral micaceo...As the dominant macrofauna in many soils,earthworms play a significant role in mineral weathering and nutrient release from mineral structures into available forms for root uptake.Phlogopite is a trioctahedral micaceous mineral that can be weathered to other minerals through release of its interlayer potassium(K).In this study,we investigated the effect of earthworm activities and associated microbial communities on phlogopite weathering during the production of phlogopite-enriched vermicompost with different quantities of phlogopite added.An experiment was run under laboratory conditions using three levels of phlogopite(0,20%and 40%by weight)in triplicates.Each Petri dish contained 20 g of a mixture of cow manure and phlogopite,and vermicomposting process was performed by inoculation of eight Eisenia foetida earthworms.Changes in clay mineralogy and C/N ratio in each dish were assessed at days 0,45,90,135,and 180 during vermicomposting.The results indicated that phlogopite was partially weathered to vermiculite and interstratified mica-vermiculite during the vermicomposting process.The rate of weathering was higher during the early stages of vermicomposting(the first 90 d).The weathering of phlogopite was influenced considerably by the activity of earthworms and associated microbial communities during the organic matter transformation process.At the early stages of the process,the weathering rate for different levels of phlogopite was not significantly different,but over time it accelerated steadily,and the difference increased.展开更多
Weathering has always been a concerned around the world,as the first and most important step in the global cycle of elements,which leads to the fractionation of isotopes on the scale of geological age.The Middle Ordov...Weathering has always been a concerned around the world,as the first and most important step in the global cycle of elements,which leads to the fractionation of isotopes on the scale of geological age.The Middle Ordovician Majiagou Formation in Daniudi area of the Ordos Basin had experienced weathering for>130 Myr.Through thin section observation,major and trace element analysis,carbon,oxygen,and magnesium isotopes composition analysis,the dolomitization modes and weathering of ancient dolo-mite in Daniudi area were analyzed in detail.The results showed that the Sabkha and brine-reflux dolomitization modes had developed,and the Mg isotopes in different layers of the karst crust were fractionated by various factors.The vertical vadose zone was affected by weathering,the Mg isotope of dolomite(δ^(26)Mgdol)showed a downward decreasing trend;the horizontal underflow zone was controlled by diagenesis and formation fluid,δ^(26)Mgdol showed a vertical invariance and negative;the main reason for Mg isotope fractionation in the deep slow-flow zone was the brine-reflux dolomitization mode during early burial period,which showed a vertical downward increase.Finally,the Mg isotope characteristic data of the ancient weathering crust were provided and the process of Mg isotope frac-tionationinthekarstcrust was explained.展开更多
This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weather...This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.展开更多
Xianglushan-type iron deposits are one of the new types of iron deposits found in the Weining Area of Western Guizhou. The iron-bearing rock system is a paleo-weathered crustal sedimentary(or accumulating) stratum bet...Xianglushan-type iron deposits are one of the new types of iron deposits found in the Weining Area of Western Guizhou. The iron-bearing rock system is a paleo-weathered crustal sedimentary(or accumulating) stratum between the top of the Middle-Late Permian Emeishan basalt formation and the Late Permian Xuanwei formation. Iron ore is hosted in the Lower-Middle part of the rock system. In terms of the genesis of mineral deposit, this type of deposit should be a basalt paleo-weathering crustal redeposit type, very different from marine sedimentary iron deposits or continental weathering crust iron deposits. Based on field work and the analytical results of XRD Powder Diffraction, Electron Probe, Scanner Electron Microscope, etc., the geological setting of the ore-forming processes and the deposit features are illustrated in this paper. The ore-forming environment of the deposit and the Emeishan basalt weathering mineralization are also discussed in order to enhance the knowledge of the universality and diversity of mineralization of the Emeishan Large Igneous Province(ELIP), which may be a considerable reference to further research for ELIP metallogenic theories, and geological research for iron deposits in the paleo-weathering crust areas of the Emeishan basalt,Southwestern, China.展开更多
The chief aim of this study is to investigate the chemical weathering process of the weathering crust in Great Wall Station region of China (in Fildes Peninsula), Antarctica by the method of sedimentology.CW,SW,GW,TW,...The chief aim of this study is to investigate the chemical weathering process of the weathering crust in Great Wall Station region of China (in Fildes Peninsula), Antarctica by the method of sedimentology.CW,SW,GW,TW,WE weathering crusts developed on volcanic clastic rock, gray aptitic basalt with tuff or basaltic bedrock. On change of minerals, geochemical behaviors of elements, migration and enrichment regularities of elements, Correlation between element geochemical behaviors, change of weathering potential of rocks in chemical weathering process are studied by us.We can see that the sequence fo weathering strengths of the abovementioned sections, from high to low, should reflected in TW, GW, CW and SWT and basical correspond with that calculated from the enrichment and differentiation indexes.展开更多
Chemical weathering can occur on Earth and other rocky planets with liquid water on their surfaces.As the Curiosity Mission has revealed that fluvio-lacustrine depositional environments once prevailed in Gale Crater,i...Chemical weathering can occur on Earth and other rocky planets with liquid water on their surfaces.As the Curiosity Mission has revealed that fluvio-lacustrine depositional environments once prevailed in Gale Crater,investigation of sediment geochemistry to interpret chemical weathering history and the possible influence of climate fluctuation seems feasible on Mars.This study examines the relationship between temperature and the degree of weathering inferred from weathering indices,and applies the suitable weathering indices to a compilation of published datasets from Gale Crater sediment.The selected weathering indices(CIA,CIW,PIA,V,W,and WIP)consistently suggest an increase followed by a more gradual increase and decrease in weathering intensity up-section,which might reflect climate variations.However,diagenetic and/or hydrothermal alteration seem to have overprinted the primary weathering signature.展开更多
基金funded by the National Natural Science Foundation of China(Nos.42173059 and 41991322)。
文摘Enhanced silicate weathering(ESW)is a geoengineering method aimed at accelerating carbon dioxide(CO_(2))removal(CDR)from atmosphere by increasing the weathering flux of silicate rocks and minerals.It has emerged as a promising strategy for CDR.Theoretical studies underscore ESW’s substantial potential for CDR and its diverse benefits for crops when applied to croplands.However,the well-known significant discrepancies in silicate weathering rates between laboratory and field conditions introduce uncertainty in CDR through ESW.By compiling data from recent literature,we calculated and compared CDR efficiency(t CO_(2)t^(-1)_(silicate)ha^(-1)y^(-1))observed in mesocosm experiments and field trials.The findings indicate that CDR efficiencies in field trials are comparable to or exceeding that observed in mesocosm experiments by 1-3 orders of magnitude,particularly evident with wollastonite application.The hierarchy of CDR efficiency among silicates suitable for ESW is ranked as follows:olivine≥wollastonite>basalt>albite≥anorthite.We suggest the potential role of biota,especially fungi,in contributing to higher CDR efficiencies observed in field trials compared to mesocosm experiments.We further emphasize introducing fungi known for their effectiveness in silicate weathering could potentially enhance CDR efficiency through ESW in croplands.But before implementing fungal-facilitated ESW,three key questions need addressing:(i)How does the community of introduced fungi evolve over time?(ii)What is the long-term trajectory of CDR efficiency following fungal introduction?and(iii)Could fungal introduction lead to organic matter oxidation,resulting in elevated CO_(2)emissions?These investigations are crucial for optimizing the efficiency and sustainability of fungal-facilitated ESW strategy.
基金financially supported by the Science and Technology Innovation Foundation of the Command Center of Integrated Natural Resources Survey Center(KC20230002)the China Geological Survey Project(DD20230471,DD20220855 and DD20243282)+1 种基金the National Natural Science Foundation of China(41872100)the National Key R&D Plan(2022YFC2903402)。
文摘Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to comprehending the developmental history and future trends of black soil,especially against the background of large-scale global cultivation and climate change.Although the importance of black soil formation and evolution cannot be ignored,the relevant research is still very scarce.In this study,a typical eight-meter-deep soil core was collected from the Keshan area of the Songnen Plain,Northeast China,where surface black soil developed on paleo-sediments.Using^(14)C dating,the formation age of the black soil was determined.Based on the characteristics of the geochemical composition,grain size and the magnetic susceptibility of the sediments,it was demonstrated that the black soil and its parent material originated from reworked loess.Furthermore,the mass transfer coefficient(τ)of some elements was determined,in order to explore the soil weathering process.By calculating the transported amount of alkaline and alkaline-earth elements,the weathering rate of parent material to black soil was found to be weak,at 0.16 kEq·ha^(-1)·year^(-1).Combining the results of dating and carbon density in the different layers of black soil,the accumulation rate of organic carbon was determined as follows:rapidly increasing in the initial period of 13.2-2.2 ka,reaching its maximum average value of 34.0 g·cm^(-2)·a^(-1)at 2.2-0.8 ka,then showing a decreasing trend with an average value of-77.5 g·cm^(-2)·a^(-1).Compared with regional climate change,Keshan black soil has developed under a colder and wetter climate during the Holocene.Predictably,ongoing global warming may lead to the degradation of black soils in the Songnen Plain,as well as in other regions.Our results will enrich geological knowledge of black soil formation and future evolutionary trends.
基金support of the National Natural Science Foundation of China(No.52171063).
文摘Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before the formation of stable rust layers,weathering steel is prone to liquid rust sagging and spattering,leading to environmental pollution and city appearance concerns.These factors limit the application and development of weathering steel.In this study,a rapid and environmentally friendly method was de-veloped by introducing alloying elements,specifically investigating the role of Sn in the rapid stabilization of rust layers in marine atmo-spheric environments.The rust layer formed on weathering low-alloy steel exposed to prolonged outdoor conditions and laboratory im-mersion experiments was explored using electron probe micro-analyzer(EPMA),micro-Raman,X-ray photoelectron spectroscopy(XPS),and electrochemical measurements.Results showed an optimal synergistic effect between Sn and Cr,which facilitated the accelerated densification of the rust layer.This beneficial effect enhanced the capability of the rust layer to resist Cl^(-)erosion and improved the protec-tion performance of the rust layer.
基金support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB 41000000(Y.L.)+4 种基金National Natural Science Foundation of China(Nos.42273042 and 41931077)"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(DHSZZ2023-3)Guizhou Provincial Foundation for Excellent Scholars Program(No.GCC[2023]088)Guizhou Provincial Science and Technology Projects:QKHJCZK[2023]-General 473NSFC Young Scientist Fund(Nos.42303041 and 42403043)。
文摘Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.
基金supported by National Natural Science Foundation of China(Grant No.42050201)National Key Research and Development Program of China(Grant No.2020YFC1522200)。
文摘Dry-wet cycle is a key factor in surface weathering of earthen heritage,which remains insufficiently explained.It involves the interaction of humidity,stress,and damage.Using the RFPA(realistic failure process analysis)numerical method,this study reproduced the processes of humidity diffusion,deformation,stress,and damage evolution under dry-wet cycles in the soil site of Suoyang City,China.The numerical results indicate that the drying phase following rainfall has the most significant deteriorative impact on the earthen heritage.The evaporation of surface moisture during this phase causes volume shrinkage,which in turn generates tensile stress and leads to the formation of numerous desiccation cracks.Desiccation cracks provide channels for moisture diffusion,which further exacerbates generation of the cracks,leading to a mutual promotion between the two phenomena.Furthermore,during the wetting phase,the model elements undergo hygroscopic expansion,resulting in a slight increase in strain and displacement.Previously formed cracks may exhibit temporary narrowing or closure,but will revert during the subsequent drying phase.Ultimately,the overall displacement increases with the number of dry-wet cycles.The findings provide a theoretical foundation for protection against surface weathering and other damage in earthen heritage in arid regions.
基金Supported by the Joint Fund of National Natural Science Foundation of China(NSFC)and Shandong Province(Nos.U22A20580,U1906210)the Laoshan Laboratory(No.LSKJ202203904)the National Natural Science Foundation of China(No.41876116)。
文摘Silicon(Si)is an important element in aquatic ecosystems.Based on the observed data in the Huanghe(Yellow)River Basin,a forward model was used to evaluate the silicate weathering rate in the Huanghe River Basin.The effects of silicate weathering,damming,and land use change on the Si concentration and flux were analyzed.Results show that the dissolved Si(DSi)concentration decreased first and then increased,and was 0.82–2.96 mg/L.As a silicon source in the Huanghe River Basin,the silicate weathering rate in the upper reaches of Lanzhou was high,and a large amount of DSi was transported to the lower reaches.Agricultural irrigation in the middle reaches caused a large amount of DSi loss,and the interception of large-scale cascade reservoirs caused a large amount of DSi retention.The DSi released by sediment re-suspension due to high runoff scouring in the downstream channel also served as a silicon source to supplement the DSi flux transported to the sea.Suspended particulate matter and biogenic Si(BSi)increased first and then decreased in the ranges of 24.1–1590.7 mg/L and 0.08–2.17 mg/L,respectively,due mainly to severe soil erosion in the eastern Loess Plateau,which caused significant amounts of phytoliths to enter the water.
基金supported by internal grant from Sultan Qaboos University(IG/DVC/ESRC/21/01).
文摘Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and open sea environments.The research focused on a cost-eff ective ex situ experiment to examine the eff ects of EW reaction pathways arising from the interactions among rock powder,seawater and CO_(2).The experimental fi ltrates from diff erent milled peridotite samples exhibit a decrease in the Mg/Ca ratio as the specifi c surface area increases,which accelerates reaction rates.This suggests that the leached Mg from the original rock may have been consumed in the formation of brucite,serpentine and carbonates during EW.Similar reaction pathways are also responsible for the chemical alterations observed in amphibolite,albeit to varying degrees.On the other hand,the experimental residues showed an increase in loss on ignition compared to the original rock,indicating that EW has facilitated the incorporation of H 2 O and CO_(2) into secondary mineral structures through various reaction pathways,leading to the formation of brucite,serpentine and carbonates.Thermal gravimetric analysis of the experimental residues confi rms the presence of these minerals based on their decomposition temperatures.Additionally,XRD analysis identifi ed a range of carbonates in the residues of both peridotite and amphibolite samples,validating the occurrence of carbonation reactions.SEM images reveal textural changes in both samples,supporting the formation of secondary minerals through EW,consistent with observations from the petrographic study of untreated samples.Control experiments on CO_(2) absorption in seawater showed a decrease in pH,highlighting ocean acidifi cation from increased CO_(2) emissions.However,when rock powder was added to the seawater-CO_(2) mixture,the pH increased.This suggests that the EW of ultramafi c rock powders can sequester CO_(2) while raising seawater pH through the formation of secondary minerals.This research could serve as an analog for EW applications,considering the worldwide abundance of ultramafi c rocks and the availability of coastal and open ocean environments.However,further research is required to understand the behavior of other elements and their impacts on ocean chemistry in EW processes before applying CO_(2) sequestration strategies.
基金supported by the High-quality Scientific Research Cultivation Project of Bengbu University(Grant No.2021pyxm03)the Natural Science Foundation of the Higher Education Institutions of Anhui Province(Grant No.KJ2021A1118)+1 种基金the Provincial Quality Engineering Project of Anhui Universities(Grant No.2022zygzts066)the Discipline(Major)Leadership Development Program of Anhui Province(DTR2023057).
文摘A micro-layered structure was observed in the stable rust layer through dry–wet cycle corrosion tests.The microstructure,element distribution,and corrosion resistance mechanism of this layer structure in the marine industrial atmosphere were investigated by focused ion beam–scanning electron microscopy and high-resolution transmission electron microscopy.The inner rust layer of weathering steel(WS)exhibited layered enrichment of Cr,Cu,Ti,and other alloying elements.This layered structure comprised a fully amorphous region rich in Cr and Ti,as well as an amorphous and nanocrystalline region rich in Fe but poor in Cr.Only the completely amorphous region of the inner rust layer demonstrated a strong adsorption effect on Cl^(−).Cr-rich amorphous region played a pivotal role in reducing the corrosion of WS in the marine industrial atmospheric environment.The interface between the amorphous and nanocrystalline regions,as well as cracks within the interlayer,facilitated Cl^(−)transport,while the intact interlayer effectively hindered HSO_(3)^(−).
基金supported by the Construction Industry Council(Grant No.CICR/01/22)the support from the General Research Fund(Grant No.17206822)of the Research Grants Council(Hong Kong).
文摘Rock classification plays a crucial role in various fields such as geology,engineering,and environmental studies.Employing deep learning AI(artificial intelligence)methods has a high potential to significantly improve the accuracy and efficiency of this task.The paper delves into the exploration of two cuttingedge AI techniques,namely Mask DINO and Mask R-CNN(convolutional neural network),as means to identify rock weathering grades and rock types.The results demonstrate that Mask DINO,which is a Detection Transformer(DETR),outperforms Mask R-CNN for the aforementioned purposes.Mask DINO achieved f-1 scores of 91% and 86% in weathering grade detection and rock type detection,as opposed to the Mask R-CNN's f-1 scores of 84% and 75%,respectively.These findings underscore the substantial potential of employing DETR algorithms like Mask DINO for automatic classification of both rock type and weathering states.Although the study examines only two AI models,the data processing and other techniques developed in this study may serve as a foundation for future advancements in the field.By incorporating these advanced AI techniques,logging personnel can obtain valuable references to aid their work,ultimately contributing to the advancement of geological and related fields.
基金support from the Third Xinjiang Scientific Expedition Program(2021XJKK0803)the National Natural Science Foundation of China(No.41930640)the Project of the Second Comprehensive Scientific Investigation on the Qinghai-Tibetan Plateau(2019QZKK1003)。
文摘Carbonic acid produced by the dissolution of atmospheric and soil CO_(2)in water is usually the most dominant catalyst for chemical weathering,but a sulfuric aciddriven phenomenon,different from usual,was found in the orogenic belt watersheds dominated by silicate bedrock.This study,rooted in comprehensive field investigations in the Manas River Basin(MRB)north of the Tianshan Mountains,delves into the mechanisms and impacts of sulfuric and carbonic acid as catalysts driving diff erent types of chemical weathering in the Central Asian Orogenic Belt.Quantitative analyses elucidate that carbonate weathering constitutes 52.4%of the total chemical weathering,while silicate and evaporite account for 18.6%and 25.3%,respectively,with anthropogenic activities and atmospheric precipitation having little eff ect.The estimated total chemical weathering rate in MRB is approximately 0.075×10^(6)mol/km^(2)/year.Quantitative findings further suggest that,preceding carbonate precipitation(<10^(4)year),chemical weathering can absorb CO_(2).Subsequently,and following carbonate precipitation(10^(4)-10^(7)year),it will release CO_(2).The release significantly surpasses the global average CO_(2)consumption,contributing to a noteworthy climate impact.This study underscores the distinctive weathering mechanisms,wherein sulfuric acid emerges as the predominant catalyst.The quantity of sulfuric acid as a catalyst is approximately three times that of carbonic acid.Sulfuric acid-driven carbonate rock weathering(SCW)is identified as the sole chemical weathering type with a net CO_(2)release eff ect.SCW CO_(2)release flux(5176 mol/km^(2)/year)is roughly 2.5 times the CO_(2)absorption by Ca-Mg silicate weathering,highlighting the pivotal role of chemical weathering in sourcing atmospheric CO_(2)over the timescales of carbonate precipitation and sulfate reduction.Lastly,this study posits that catalyst and transport limitations are the most plausible critical factors in MRB.The interplay between sulfuric acid and dissolved CO_(2)competitively shapes the types and rates of chemical weathering reactions.
基金supported by the National Natural Science Foundation of China(Grant Nos.4121000441661144042+1 种基金 41603018)National Basic Research Program(973project)of China(2013CB956401)
文摘Exploring the relationship between weathering and erosion is essential for understanding the evolution of landscapes and formation of soil under the influence of climate, tectonics, and topography. We measured the bulk chemistry of regoliths and calculated their weathering rates and intensity in three locations in China: Inner Mongolia in the mid-temperate semi-humid zone; Jiangxi Province, in the mid-subtropical humid zone; and Hainan Province, in the tropical humid zone. These profiles exhibited increased weathering with increasing temperature and precipitation.The low-gradient profile exhibited stronger weathering of saprolite than of soil, whereas the high-gradient profile showed a more constant weathering pattern. The regolith in the cold climate was the product of easily weatherable minerals, whereas weathering of K-feldspar and even secondary minerals occurred in hot and humid climates. The weathering of subtropical profiles was both supply-and kinetic-limited, controlled by weathering and erosion. The tropical profile experienced supply-limited weathering,indicating slow erosion and an intense weathering profile;the mid-temperate profile was not classifiable due to weak erosion and weathering. Long-term weathering fluxes of these profiles show that Si, Na, and K(or Mg) represent thebulk of the mass lost through weathering. This study underscores that weathering of granitic regolith is controlled by both climatic conditions and landscape.
基金supported by the National Natural Science Foundation of China (30671644, 30771680)
文摘Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mechanical properties of the composites before and after UV accelerated weathering. HDPE, wood fibers, pigments and other processing additives were dry-mixed in a high-speed mixer. The mixtures were extruded by two-step extrusion process with a self-designed twin-screw/single-screw extruder system. Color of the samples was determined according to CIE 1976 L^＊a^＊b^＊ system by a spec- trophotometer and the bending properties were tested to evaluate the mechanical properties before and after accelerated UV weathering. The result shows that the modulus of elasticity of WF/HDPE did not obvi- ously changed after incorporating with the pigments, but the bending strength increased. After accelerated aging for 2000 h, both color and mechanical properties significantly changed. Iron oxide red and black performed better than the other two pigments, and the pigments dosage of 2.28% in the composites is favourable.
基金funded by National Natural Science Foundation of China 30671644 and NCET
文摘Rice-hull powder is widely used in manufacturing reinforced plastic composites.However,its weathering ability is rarely considered.We studied the performance of two types of rice-hull-polyethylene（RH-PE） composites after they were exposed outdoor to natural weathering for two years.The samples did not change in bending strength and elasticity modulus.At the end of the testing period,colour lightness had increased by more than 23% and total colour had changed by more than 9 units.This means the colour evidently differentiate from the original colour that the customers choose.The analyses of Fourier-transform infrared（FTIR） and X-ray photoelectron spectroscopy（XPS） showed that oxidation had occurred on sample surfaces.Red lumber presented an obvious C=O peak after weathering,while yellow lumber did not present an obvious peak as evidence of oxidation.Both types of lumbers showed a reduction of lignocellulosic groups and amorphous regions of PE.
基金jointly financially supported by the National Natural Science Foundation of China (Grant Nos. 41772197, 41761002)the Project of Evaluation Research and the Protection and Utilization of the Danxia Landscape in Yan’an City (Grant No. 201901)。
文摘Cavernous weathering is commonly found on sandstone slopes in different environments. Either a single dominant process or polygenetic agents require to be invoked in order to interpret the development. The Yongningshan hill of the central Loess Plateau is representative of cliff dwellings in Northwest China, which is characterized by well-developed cavernous weathering features and provides a good opportunity for the better understanding of sandstone weathering in the Loess Plateau. Multiple methods, including field survey, in-situ rock strength measurement, along with experiments on samples for microscopic observation, element composition and salt chemistry, were employed to investigate the controlling factors of cavernous weathering. The results show that cavern development is different on the four slopes with the western slope hosting massive honeycombs, tafoni and hardened surfaces. The porous and permeable aeolian sandstones are fundamental, because they provide space and pathways for the transportation of water and salt, honeycombs dominantly aligning within the lamination of cross-beds. The environmental factors such as the seasonal wetting and drying cycle, aeolian salt, moisture and water vapor are key factors for the development of cavernous weathering forms. The northern and northwestern wind-blown dust storms have brought abundant salts, the lengthier dry periods of the wetting and drying cycle being beneficial for salt accumulation within caverns, favoring salt weathering.
基金We would like to thank the Iranian National Science Foundation(No.96002378)for financially supporting this research.
文摘As the dominant macrofauna in many soils,earthworms play a significant role in mineral weathering and nutrient release from mineral structures into available forms for root uptake.Phlogopite is a trioctahedral micaceous mineral that can be weathered to other minerals through release of its interlayer potassium(K).In this study,we investigated the effect of earthworm activities and associated microbial communities on phlogopite weathering during the production of phlogopite-enriched vermicompost with different quantities of phlogopite added.An experiment was run under laboratory conditions using three levels of phlogopite(0,20%and 40%by weight)in triplicates.Each Petri dish contained 20 g of a mixture of cow manure and phlogopite,and vermicomposting process was performed by inoculation of eight Eisenia foetida earthworms.Changes in clay mineralogy and C/N ratio in each dish were assessed at days 0,45,90,135,and 180 during vermicomposting.The results indicated that phlogopite was partially weathered to vermiculite and interstratified mica-vermiculite during the vermicomposting process.The rate of weathering was higher during the early stages of vermicomposting(the first 90 d).The weathering of phlogopite was influenced considerably by the activity of earthworms and associated microbial communities during the organic matter transformation process.At the early stages of the process,the weathering rate for different levels of phlogopite was not significantly different,but over time it accelerated steadily,and the difference increased.
基金supported by the National Natural Science Foundation of China(42072177)National Natural Science Foundation of China(U19B6003)Frontier Project of Chinese Academy of Sciences(XDA14010201).
文摘Weathering has always been a concerned around the world,as the first and most important step in the global cycle of elements,which leads to the fractionation of isotopes on the scale of geological age.The Middle Ordovician Majiagou Formation in Daniudi area of the Ordos Basin had experienced weathering for>130 Myr.Through thin section observation,major and trace element analysis,carbon,oxygen,and magnesium isotopes composition analysis,the dolomitization modes and weathering of ancient dolo-mite in Daniudi area were analyzed in detail.The results showed that the Sabkha and brine-reflux dolomitization modes had developed,and the Mg isotopes in different layers of the karst crust were fractionated by various factors.The vertical vadose zone was affected by weathering,the Mg isotope of dolomite(δ^(26)Mgdol)showed a downward decreasing trend;the horizontal underflow zone was controlled by diagenesis and formation fluid,δ^(26)Mgdol showed a vertical invariance and negative;the main reason for Mg isotope fractionation in the deep slow-flow zone was the brine-reflux dolomitization mode during early burial period,which showed a vertical downward increase.Finally,the Mg isotope characteristic data of the ancient weathering crust were provided and the process of Mg isotope frac-tionationinthekarstcrust was explained.
文摘This study investigated the effects of weathering depth and thickness on the failure mechanisms of rock samples through experimental and numerical methods.The first configuration involved conducting artificial weathering on limestone using the freezing and thawing(F-T)for 40 cycles.The mechanical parameters of the samples were measured at the end of the 40th cycle.In the second configuration,a series of specimens underwent salt crystallization(S-C)tests for 20 cycles.Experimental results were validated using discrete element method(DEM).Next,the weathered limestone model with dimensions of 108 mm54 mm were prepared.The weathering layers were tested at four different thicknesses(i.e.2.5 mm,5 mm,7.5 mm,and 10 mm)and three different positions(at the surface,5 mm under the rock surface,and 10 mm under the rock surface).According to the results,weathering depth and thickness have a considerable effect on the failure process.The results also showed a correlation between the values of compressive strength and failure mechanisms associated with the weathering layer.The numerical results revealed that the tension crack was the dominant factor.Additionally,with increasing weathering thickness,Young's modulus,crack initiation stress,and final strength decreased in constant weathering depth.The results also demonstrated that the failure progress of the numerical models was similar to that observed in the laboratory.
基金supported by PMO of Guizhou Institute of Technology for the Study of Iron Deposit Oreforming Rule,Ore-controlling Factors and Ore-forming Predication in the Western Region of Guizhou Province(No.406,2015)PMO of Innovation Team of Guizhou General Institutes of Higher Education for Survey of Underlying Ore Deposit(No.56,2015)+1 种基金the Education Reform of the Guizhou Institute of Technology(No.2015JGY18)the Study for Existing State of Rare Earth Elements in Low Grade Iron Ore from Associated Multi-metal Deposits in Northwest Guizhou(Ref.No.05,2014)
文摘Xianglushan-type iron deposits are one of the new types of iron deposits found in the Weining Area of Western Guizhou. The iron-bearing rock system is a paleo-weathered crustal sedimentary(or accumulating) stratum between the top of the Middle-Late Permian Emeishan basalt formation and the Late Permian Xuanwei formation. Iron ore is hosted in the Lower-Middle part of the rock system. In terms of the genesis of mineral deposit, this type of deposit should be a basalt paleo-weathering crustal redeposit type, very different from marine sedimentary iron deposits or continental weathering crust iron deposits. Based on field work and the analytical results of XRD Powder Diffraction, Electron Probe, Scanner Electron Microscope, etc., the geological setting of the ore-forming processes and the deposit features are illustrated in this paper. The ore-forming environment of the deposit and the Emeishan basalt weathering mineralization are also discussed in order to enhance the knowledge of the universality and diversity of mineralization of the Emeishan Large Igneous Province(ELIP), which may be a considerable reference to further research for ELIP metallogenic theories, and geological research for iron deposits in the paleo-weathering crust areas of the Emeishan basalt,Southwestern, China.
文摘The chief aim of this study is to investigate the chemical weathering process of the weathering crust in Great Wall Station region of China (in Fildes Peninsula), Antarctica by the method of sedimentology.CW,SW,GW,TW,WE weathering crusts developed on volcanic clastic rock, gray aptitic basalt with tuff or basaltic bedrock. On change of minerals, geochemical behaviors of elements, migration and enrichment regularities of elements, Correlation between element geochemical behaviors, change of weathering potential of rocks in chemical weathering process are studied by us.We can see that the sequence fo weathering strengths of the abovementioned sections, from high to low, should reflected in TW, GW, CW and SWT and basical correspond with that calculated from the enrichment and differentiation indexes.
基金supported by the NRF grant funded by the Korean Government(MSIT,No.2022R1A2C1004798)Global-Learning&Academic research institution for Master’s·PhD students,and Postdocs(LAMP)Program of the National Research Foundation of Korea(NRF)grant funded by the Ministry of Education(No.RS-2023-00301702).
文摘Chemical weathering can occur on Earth and other rocky planets with liquid water on their surfaces.As the Curiosity Mission has revealed that fluvio-lacustrine depositional environments once prevailed in Gale Crater,investigation of sediment geochemistry to interpret chemical weathering history and the possible influence of climate fluctuation seems feasible on Mars.This study examines the relationship between temperature and the degree of weathering inferred from weathering indices,and applies the suitable weathering indices to a compilation of published datasets from Gale Crater sediment.The selected weathering indices(CIA,CIW,PIA,V,W,and WIP)consistently suggest an increase followed by a more gradual increase and decrease in weathering intensity up-section,which might reflect climate variations.However,diagenetic and/or hydrothermal alteration seem to have overprinted the primary weathering signature.
