Shale contains a lot of clay minerals. Clay minerals mainly exist in nano- and micro-meter sized particles, and the pore structure is complex, which leads to its extremely complex wettability. The surface wettability ...Shale contains a lot of clay minerals. Clay minerals mainly exist in nano- and micro-meter sized particles, and the pore structure is complex, which leads to its extremely complex wettability. The surface wettability of clay minerals significantly affects the oil and gas-bearing capacity of shale reservoirs. Therefore, studying the wettability of common clay minerals in shale at the nanoscale is of great significance for shale hydrocarbon exploration and development. In this study, the wetting behavior of water in n-hexane and toluene on different clay mineral surfaces at the nanoscale was systematically studied using Molecular dynamics (MD) simulation. And the influencing factors of wettability were analyzed. Through the analysis of the morphological changes of water, relative concentration of water, RDF and interaction energy, it is concluded that the following order of water wettability on the surfaces of clay minerals: montmorillonite > chlorite > kaolinite > illite. Through the analysis of interaction energy, it is concluded that the hydrophilicity of four clay minerals is stronger than that of lipophilicity. And the main interactions between water and oil and the mineral surfaces were van der Waals force and electrostatic force. In addition, the temperature, liquid hydrocarbon type, and mineralization of water affected the wettability of clay minerals. The concentration of water on the surfaces of montmorillonite, kaolinite, and illite decreased with increasing temperature, and the water wettability decreased. At 298 K, the hydrophilicity of the surfaces of the clay minerals in toluene follows the order montmorillonite > chlorite > kaolinite > illite. The higher the NaHCO3 concentration in water, the weaker the wettability of the clay mineral surfaces to water. By comparing the previous experimental results with the MD simulation results, similar wetting characteristics were obtained, and the reliability of the simulation results was verified. MD simulation was used to explore the water wetting of the surfaces of four clay minerals in a shale reservoir from the micro level. This makes up for the lack of experimental means for clarifying the flow and production mechanisms of shale oil and gas and effectively improves the evaluation technology of shale.展开更多
Clay mineral composition represents an important tracer of sediment source area,migration processes,and paleoclimatic conditions.Clay mineral analysis was performed on 15 surface sediment samples collected from the co...Clay mineral composition represents an important tracer of sediment source area,migration processes,and paleoclimatic conditions.Clay mineral analysis was performed on 15 surface sediment samples collected from the coast of Chanthaburi,Thailand.Results show that the composition of clay minerals in the study area differs substantially from that in surrounding regions of the Gulf of Thailand.The clay minerals of the Chanthaburi coast are dominated by kaolinite(~56%),followed by smectite(~21%),illite(~14%),and low concentrations of chlorite(~8%).The average illite chemistry index and crystallinity are 0.93 and 0.32,respectively.Comparative analysis of the clay mineral composition of surface sediments in several typical areas around the Gulf of Thailand indicated that the clays of the Chanthaburi coast are mainly derived from parent rock weathering in the small watersheds of the Chanthaburi and Welu rivers and the surrounding islands.Terrestrial input from the northern coast of the Gulf of Thailand(excluding the Mekong River)was previously considered negligible;however,the present results indicate that such input has impact on the eastern Gulf of Thailand.The warm humid climatic conditions in Southeast Asia are the primary factors that affect the strong chemical weathering in the study area,followed by the nature of the parent rock.展开更多
Rheological mechanical properties of the soft rock are afected signifcantly by its main physical characteristics-clay mineral.In this study,taking the mudstone on the roof and foor in four typical mining regions as th...Rheological mechanical properties of the soft rock are afected signifcantly by its main physical characteristics-clay mineral.In this study,taking the mudstone on the roof and foor in four typical mining regions as the research object,frstly,the clay mineral characteristic was analyzed by the X-ray difraction test.Subsequently,rheological mechanical properties of mudstone samples under diferent confning pressures are studied through triaxial compression and creep tests.The results show that the clay mineral content of mudstone in diferent regions is diferent,which leads to signifcant diferences in its rheological properties,and these diferences have a good correlation with the content of montmorillonite and illite-montmorillonite mixed layer.Taking the montmorillonite content as an example,compared with the sample with 3.56%under the lower stress level,the initial creep deformation of the sample with 11.19%increased by 3.25 times,the viscosity coefcient and longterm strength decreased by 80.59%and 53.94%,respectively.Furthermore,based on the test results,the damage variation is constructed considering the montmorillonite content and stress level,and the M–S creep damage constitutive model of soft rock is established.Finally,the test results can be ftted with determination coefcients ranging from 0.9020 to 0.9741,which proves that the constitutive relation can refect the infuence of the clay mineral content in the samples preferably.This study has an important reference for revealing the long-term stability control mechanism of soft rock roadway rich in clay minerals.展开更多
The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediment...The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud.From the inside to the outside,the grain size goes from fine to coarse.Aside from the“grain size effect”,hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements(REEs).Based on the grain size,REEs,and clay mineral composition of 300 surface sediments,as well as the sedimentary genesis,the northern ECS shelf is divided into three geochemical zones:southwestern Cheju Island Mud Area(ZoneⅠ),Changjiang Shoal Sand Ridges(ZoneⅡ-1),Sand Ridges of the East China Sea shelf(ZoneⅡ-2).The northern ECS shelf is mostly impacted by Chinese mainland rivers(the Changjiang River and Huanghe River),and the provenance and transport mechanism of sediments of different grain sizes is diverse.The bulk sediments come primarily from the Changjiang River,with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current,and less from Korean rivers.Among them,surface sediments in the southwestern Cheju Island Mud Area(ZoneⅠ)come mostly from the Changjiang River and partly from the Huanghe River.It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf,which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River.The Changjiang Shoal Sand Ridges(ZoneⅡ-1)were developed during the early-middle Holocene sea-level highstand.It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current,North Jiangsu Coastal Current,and Changjiang Diluted Water.The surface sediments mainly originate from the Changjiang River and Huanghe River,with the Changjiang River dominating,and the Korean River(Hanjiang River)influencing just a few stations.Sand Ridges of the East China Sea shelf(ZoneⅡ-2)are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene.The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River,with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents.展开更多
Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global ocea...Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global oceans except in South Mid-Atlantic Ridge(SMAR)due to limited explorations.Thus,32 MS and 34 non-MS(NMS)samples were analyzed to clarify the distribution characteristics and mineral compositions of clay minerals.All the sediments were collected along the SMAR between 12°S and 27°S.After removal of organic matter and carbonate,clay fractions(<2μm)were investigated by Xray diffraction(XRD)analysis.Results show that clay mineral assemblages of surface MS consist dominantly of smectite,less abundant illite,chlorite,and kaolinite in average weight percentage of 30%,21%,18%,and 16%,respectively.On the other hand,clay mineral assemblages in the NMS consist mainly of illite,less abundant kaolinite,chlorite,and very scarce smectite in average weight percentage of 47%,29%,24%,and 0.2%,respectively.The clay fractions in MS are mainly composed of amorphous or poorly crystallized Fe/Mn oxyhydroxides,clay mineral,quartz,and plagioclase.However,the counterparts in the NMS are mainly composed of well-crystallized clay minerals,quartz,and plagioclase without the presence of Fe/Mn oxyhydroxides.It is suggested that most of the illite,kaolinite,and chlorite in both MS and NMS are likely aeolian dust in origin from South Africa continent.In addition,the abundance of kaolinite dominates the clay mineral assemblage at low latitudes,where the intensive chemical weathering of continental source rocks facilitating the formation of kaolinite.In terms of smectite,it is indicated of authigenic origin in consideration of only smectite is available in several MS and the absence in NMS.Moreover,the MS samples with only smectite available are always accompanied by goethite.Therefore,it is assumed that most of smectite occurred in studied area is the results of interaction between hydrothermal Fe-oxyhydroxide,silica,and seawater.展开更多
The micro-nano pore structure of conglomerate in the Lower Karamay Formation of the Xinjiang Oilfield,Junggar Basin,northern China is characterized to predict its impact on fluid reserves and seepage.Authigenic clay m...The micro-nano pore structure of conglomerate in the Lower Karamay Formation of the Xinjiang Oilfield,Junggar Basin,northern China is characterized to predict its impact on fluid reserves and seepage.Authigenic clay minerals are mainly kaolinite(67%),followed by an illite/smectite mixed layer(18%),illite(10%),and chlorite(5%).For kaolinite,pore throats between 0–200 nm are dominant,accounting for 90%of the total pore throats.For illite/smectite mixed layer,pore throats also between 0–200 nm account for nearly 80%,while pore throats between 200-500 nm only account for 15%.For illite,pore throats below 100 nm account for about 80%,while pore throats in the range of 100–500 nm only account for 20%.For chlorite,most throats are below 200 nm.The pore roundness of illite is the highest,while the pore roundness of chlorite is relatively lower.The lower limits of the dynamic and static pore throat radii are 42.128 nm and 72.42 nm,respectively.The theoretical contribution rates of the illite/smectite mixed layer,kaolinite,illite and chlorite to storage/seepage are 60%/45.86%,52.72%/38.18%,37.07%/28.78%and 32.97%/26.3%,respectively.Therefore,the contribution rates of clay minerals in the study area are as follows:illite/smectite mixed layer,kaolinite,illite and chlorite.展开更多
The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new ins...The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new insights into the ongoing debate about the frictional strength of brittle fault(Haines and van der Pluijm,2012).However,neither the conditions nor the processes展开更多
Studying the sedimentary characteristics of the muddy area along the Yellow Sea shelf is of great significance for deep-ening the understanding of the climate and environment evolution since the last glacial period.Re...Studying the sedimentary characteristics of the muddy area along the Yellow Sea shelf is of great significance for deep-ening the understanding of the climate and environment evolution since the last glacial period.Recently,a small muddy area developed in the southern Weihai offshore has attracted a lot of attention.Based on high-resolution grain size,clay mineral,AMS14C,and OSL data of sediments from the core WHZK01 in the muddy area,we acquired a new understanding of sedimentary characteristics,sources and paleoclimatic environment during the last 13 kyr.The results show that the core WHZK01 sediments were mainly from the Yellow River and local rivers along the coast.However,the sources varied for different deposition units.The riverbed(before 13 kyr BP)and fluvial plain deposits(13-10 kyr BP)were mainly from local river inputs.The very thin littoral deposits from 10 kyr BP to 8 kyr BP also mainly originate from coastal river inputs,while the littoral-neritic deposits since 8 kyr BP were dominated by the Yellow River materials and partly supplied by the coastal rivers and the island erosion.In addition,five events related with the strong East Asian winter monsoon(EAWM)during the intervals of 13.0-11.0 kyr BP,10.0-8.2 kyr BP,7.0-5.0 kyr BP,3.5-2.5 kyr BP,and 1.2-0.5 kyr BP were iden-tified.Three events related with the enhancement of the EAWM since the middle Holocene have strengthened the transport capacity of the coastal currents of the Shandong Peninsula.Meanwhile,more Yellow River-derived distal sediments were deposited to the southern Weihai offshore and formed wedge-shaped muddy bodies.In short,the ratio of smectite/illite could be used as an effective EAWM indicator since 13 kyr BP on the northwestern shelf of the South Yellow Sea.展开更多
The kinetics of Cu ion exchange on Na-montmorillonite clay mineral has been investigated at three temperatures, in three solvents: H2O, ethylene glycol and glycerol. Solvent effects on the reaction rate have been disc...The kinetics of Cu ion exchange on Na-montmorillonite clay mineral has been investigated at three temperatures, in three solvents: H2O, ethylene glycol and glycerol. Solvent effects on the reaction rate have been discussed. The thermodynamic activation parameters were calculated and discussed in terms of solvation effects. The determined isokinetic temperature indicates that the reaction is enthalpy controlled where the interaction between solvent and clay surface plays an important role. A reaction mechanism which describes the solvent effect on the rate of Cu ion exchange is proposed.展开更多
The thermal properties such as specific heat capacity and heat dissipation of peloids play an important role in therapeutic applications. Therefore, these properties were determined on the peloids samples taken from s...The thermal properties such as specific heat capacity and heat dissipation of peloids play an important role in therapeutic applications. Therefore, these properties were determined on the peloids samples taken from spas where peloid applications are used in Turkey. In addition, some pure clay minerals were investigated to determine their suitability as possible constituents of therapeutic peloids and to make recommendations for preparing the most usable peloids for thermal therapy. For this aim, the mineralogical and thermal properties of samples were investigated using X-ray diffraction (XRD) and Differential Scanning Calorimeter (DSC). The mineralogical compositions of the peloid samples are not homogenous, and their clay mineral content is approximately 60%, and the most abundant clay mineral is calcium montmorillonite. The cooling time of peloids are between 20 and 25 minutes, which is suitable for therapy and thus these peloids are suitable for using in health problems requiring heat treatment. The samples have favorable heat dissipation capacity and partially cooling kinetics. Specific heat capacity of the peloid samples is partially appropriate for heat therapy and these values range from 0.60 to 1.41 J/g·°C, and partially high in peloids with high smectite content. The pure sepiolite samples have higher heat dissipation properties than those of other clay minerals especially illites and kaolinites. Ca-montmorillonite and kaolinite have the lowest specific heat values while sepiolite samples have higher values. Sepiolite and partly Na-Ca-montmorillonite are more appropriate than the other studied clay minerals as a peloid constituent especially for therapy of musculoskeletal pain.展开更多
As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolia...As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolian dust transported eastward from the Asian interior.Clay minerals,as the major fine-grained weathering products of continental rocks,can be readily transported by wind or currents over long distances and thus have been widely used in the reconstruction of paleoclimate and weathering history.However,the overall evolutionary tendency and response mechanism of clay mineral records over large spatial and long timescales across Asia remain unclear.Here,two continuous and high-resolution clay mineral records since 30 Ma were reconstructed from sediments at Deep Sea Drilling Program(DSDP)Sites 292 and 296 in the Philippine Sea.Clay minerals and Sr-Nd isotope compositions were used to constrain provenance and reconstruct the drying history of the dust source region since the Oligocene.The results show that the clay-sized detrital sediments in the Philippine Sea are a mixture of Asian eolian dust and volcanic materials from the West Pacific arcs.Based on the clay mineral compositions and eolian flux,we reveal that the Asian interior has been continuously drying since the late Oligocene and that stepwise enhanced aridification occurred at approximately 20,14,7,and 3 Ma.Compared with other regions of the world,the relative contents of illite and chlorite increased more dramatically in Asia during the late Cenozoic,and the inconsistency became more obvious at approximately 20 Ma.Since 3 Ma,illite and chlorite have increased consistently across the globe.Combined with the Asian tectonic and climatic history,we suggest that the increase in illite and chlorite from Asia between 20 and 3 Ma was mainly in response to the uplift of the Himalayan-Tibetan Plateau,whereas after 3 Ma,it was primarily controlled by global cooling driven by the expansion of the Arctic ice sheet.展开更多
Analyses of clay minerals within the Early Cretaceous Weald Basin,Southeast England reveal kaolinite,illite and chlorite as the main detrital clay minerals while glauconite and smectite are subordinates.A kaolinite-ri...Analyses of clay minerals within the Early Cretaceous Weald Basin,Southeast England reveal kaolinite,illite and chlorite as the main detrital clay minerals while glauconite and smectite are subordinates.A kaolinite-rich assemblage which characterized the sand-dominated Ashdown and Tunbridge Wells Sand formations and an illite-dominated assemblage associated mostly with the Wadhurst Clay and Weald Clay formations are recognized.Kaolinite was enriched in the Ashdown and Tunbridge Wells Sand formations during warm and humid climate with high precipitation that encouraged chemical weathering and leaching,while cold and dry conditions favoured the concentration of illite in the Wadhurst Clay and Weald Clay formations.Rainfall patterns associated with warm climate were drastically reduced during the drier climatic conditions.Most clay minerals are detrital in origin,with chlorite being more prominent than previously recognized.Contrary to previous studies and assumptions,this study revealed that authigenic clay minerals are present in the Hastings Beds,with vermiform and mica-replacive kaolinite being the most common,consistent with humid depositional environments.Isolated authigenic illite is also present,along with a chloritized grain,providing evidence for mesodiagenesis.The absence of dickite and occurrence of kaolinite,suggest that authigenic illite formed in relatively shallow burial conditions,indicating a maximum burial depth of2500 m-3000 m,about 1000 m deeper than previous estimates of 1500 m-2000 m.Authigenic clay minerals are absent in the Weald Clay Formation possibly because of hindered flow of meteoric water and limited growth space for authigenic minerals.This study is significant in:1)reinforcing multiple methods to facilitate a robust and balanced knowledge of formation and transformation of clay minerals;2)investigating detrital and authigenic clay mineral assemblages when assessing the palaeoenvironments of sedimentary basins.展开更多
Aluminosilicate clay mineral(ACM)is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring.In past two decades,in-depth understanding on unique ...Aluminosilicate clay mineral(ACM)is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring.In past two decades,in-depth understanding on unique layered structure and abundant surface proper-ties endows ACM in the emerging research and application fields.In field of solar-chemical energy conversion,ACM has been widely used to support various semiconductor photocata-lysts,forming the composites and achieving efficient conversion of reactants under sunlight irradiation.To date,classic ACM such as kaolinite and montmorillonite,loaded with semi-conductor photocatalysts has been widely applied in photocatalysis.This review summaries the recent works on ACM-based composites in photocatalysis.Focusing on the properties of surface and layered structure,we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM,i.e.,type 1∶1 and type 2∶1.Not only large surface area and active surface hydroxyl group assist the substrate adsorption,but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts.Besides,we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process.This review could inspire more upcoming design and synthesis for ACM-based photocatalysts,leading this kind of economic and eco-friendly materials for more practical application in the future.展开更多
The unique luminescent performance of lanthanide complexes/clay minerals hybrid materials has been fascinating many researchers for recent decades.It not only retains the excellent luminescent characteristics of lanth...The unique luminescent performance of lanthanide complexes/clay minerals hybrid materials has been fascinating many researchers for recent decades.It not only retains the excellent luminescent characteristics of lanthanide complexes but also improves the poor stability of the complexes.In this article,we introduce the luminescence mechanism of lanthanide complexes and point out the necessity of their combination with clay minerals.After the analysis of the structure and interlayer environment differences of 1:1-type and 2:1-type clay minerals,the intercalation methods(covalent grafting and ion exchange)appropriate for different clay minerals are summarized with examples.Based on the luminescence characteristics of the hybrid materials,the applications of these materials as luminescent probes in recognition of specific metal cations and molecules,detection of pH value,and temperature are reviewed.Finally,the current problems in the preparation of lanthanide complexes/clay minerals hybrid luminescent materials and shortcomings that need improvement in their performance are analyzed,and the application prospect is forecast.展开更多
Greenish clays often occur as thin layers in Early Cretaceous shallow-water carbonatesediments of Istria where they mark the top of fining upwards sequences. When they showevidence of subaerial exposure and pedogenesi...Greenish clays often occur as thin layers in Early Cretaceous shallow-water carbonatesediments of Istria where they mark the top of fining upwards sequences. When they showevidence of subaerial exposure and pedogenesis they are considered paleosols. The claymineralogical composition is as follow: (1) randomly oriented I/S mixed layer, (2) regularlyoriented I/S mixed layer, (3) illitic material, (4) kaolinite and (5) chlorite. The insoluble limestoneresidue situated immediately below the greenish clays is dominated by smectite, and also containskaolinite and illitic material. The very high smectite content in the insoluble residue is probablythe result of additions of volcanic dust during carbonate sedimentation. That clay mineralcomposition in the pelitic material clearly indicates the influence of both pedogenic and diageneticprocesses. It may also indicate additional volcanic dust contribution before and during thesubaerial exposure.展开更多
Crystallinity,polytype,and morphology of clay minerals in the Luochuan loess-palaeosols in Shaanxi Province,northwest China were studied in order to have an insight into their origin using X-ray diffraction(XRD)analys...Crystallinity,polytype,and morphology of clay minerals in the Luochuan loess-palaeosols in Shaanxi Province,northwest China were studied in order to have an insight into their origin using X-ray diffraction(XRD)analysis and scanning electron microscopy(SEM)methods.The SEM observations showed that the morphology of some illites seems to be lath-shaped crystals.An analysis of illite crystallinity(IC)on the Luochuan section indicated that the origin of illite was related to the rocks of an anchizone.Most illite in the Luochuan loess-palaeosol section were of 2M1 polytype,but some were of 1M polytype formed by weathering of feldspar in the process of pedogenesis.Illite in the Luochuan section has undergone both physical and chemical weathering.These results revealed that most illite were of detrital origin related to the source area of an anchizone,but parts of the illite were of an authigenic origin formed during pedogenesis after sedimentation.Chlorites in the samples of the Luochuan section were mainly composed of irregular flaky grains and their crystallinity was good.These showed that chlorite had the detrital origin formed by physical weathering.Kaolinite crystallinity was relatively good.The value of CIA on the Luochuan section ranges from 61.9 to 69,and therefore kaolinite could not be formed during weathering and pedogenesis.These results indicated that the kaolinite had a detrital origin.Morphology of smectite seems to be capillaceous.The XRD patterns of all samples contained diffraction peaks at 1.5218Å(nontronite)and 1.5052Å(montmorillonite),thus indicating an intermediate composition between trioctahedral and dioctahedral smectite.The smectite crystallinity was very poor.These results revealed that smectite in the study area was authigenic rather than detrital origin.展开更多
Obtaining a continuous sedimentary record of Cenozoic East Asian paleoclimate change is key to understand the origin,evolution and driving mechanism of the East Asian monsoon and climate change.Based on the continuous...Obtaining a continuous sedimentary record of Cenozoic East Asian paleoclimate change is key to understand the origin,evolution and driving mechanism of the East Asian monsoon and climate change.Based on the continuous Cenozoic fluvial and lacustrine sedimentary sequence in the Weihe Basin,central China,we carried out research on the content and crystal parameters of clay minerals.The paleoclimate change since the middle Eocene was reconstructed accordingly.The results show that smectite and illite are the dominant clay minerals in fluvial-lacustrine sediments of Weihe Basin.The crystallinity of illite,the chemical index of illite,the ratio of smectite to illite and chlorite decrease gradually,which indicates that chemical weathering in the Weihe River watershed stepwise weakened since the middle Eocene,under the background of a semi-arid and semi-humid climate.The formation of palygorskite may be affected by a weak diagenesis.In this case,the content of smectite and the illite crystallinity caused by the weathering in the corresponding period may be actually higher than that of the current,which indicates that the climate in the Weihe Basin region was relatively warm and humid from the middle Eocene to Pliocene.With the decrease of Cenozoic global temperature and the continuous accumulation of sediments,the intensity of chemical weathering in the Weihe Basin gradually weakened,and the East Asian monsoon climate gradually evolved until becoming dry in the Quaternary.Evidence from clay minerals also indicates that the aridification in the Weihe Basin from the late Eocene to the Oligocene may be a response to the global cooling event at the Eocene-Oligocene transition.展开更多
The Middle Miocene Climate Transition(MMCT,~14 Ma)is the largest cooling event in the Cenozoic“Coolhouse”,which significantly impacts the global chemical weathering pattern.In this paper,the responses of the MMCT gl...The Middle Miocene Climate Transition(MMCT,~14 Ma)is the largest cooling event in the Cenozoic“Coolhouse”,which significantly impacts the global chemical weathering pattern.In this paper,the responses of the MMCT global cooling event in the deep South China Sea were studied by clay mineral assemblages analysis of the oceanic red beds(ORB)at International Ocean Discovery Program(IODP)Expedition 368 Site U1502.The results show that the clay mineral assemblages of the ORB at Site U1502 are mainly composed of smectite(56–88%),illite(7–29%),and kaolinite(6–20%),without chlorite.The contents of these clay minerals and illite crystallinity show a four-stage variation pattern during early-middle Miocene(22.8–10.8 Ma).Smectite decreased from average 81%during 22.8–16.2 Ma and 16.2–14.4 Ma to average 67%during 13.8–10.8 Ma,with a rapid decrease of~14%during 14.4–13.8 Ma.On the contrary,illite and kaolinite increased rapidly by~8%and~6%,respectively,during 14.4–13.8 Ma.Illite crystallinity increased from average 0.18°Δ2θduring 22.8–16.2 Ma to average 0.19°Δ2θduring 16.2–14.4 Ma,and then decreased rapidly by~0.02°Δ2θduring 14.4–13.8 Ma.The provenance analysis of clay minerals shows that illite and kaolinite mainly originated from South China landmass due to physical erosion,while smectite mainly came from the Luzon arc as the product of chemical weathering.Therefore,smectite/illite ratio and illite crystallinity are used as proxies of chemical weathering intensity in the early-middle Miocene.High values of the ratio and the crystallinity represent the enhanced chemical weathering,whereas low values indicate the weakened chemical weathering or the strengthened physical erosion process.The smectite/illite ratio and illite crystallinity both decreased rapidly during 14.4–13.8 Ma,indicating the chemical weathering in the surrounding area of the South China Sea weakened rapidly,which we believe is the result of the MMCT event forcing.In addition,their values increased slightly during 16.2–14.4 Ma,which is in response to the relatively enhanced chemical weathering during the Middle Miocene Climate Optimum(MMCO).The variation pattern of clay mineral assemblages of the early-middle Miocene ORB in the South China Sea and its rapid transformation during the MMCT reveal that the Cenozoic cooling played a specific role in controlling the chemical weathering of the Earth’s surface.展开更多
This research investigates the adsorptionmechanisms of fluoride(F)on four clay minerals(kaolinite,montmorillonite,chlorite,and illite)underdifferent F^(-)concentrations and reaction times by probingtheir fluoride supe...This research investigates the adsorptionmechanisms of fluoride(F)on four clay minerals(kaolinite,montmorillonite,chlorite,and illite)underdifferent F^(-)concentrations and reaction times by probingtheir fluoride superficial layer binding energies and elementcompositions using X-ray photoelectron spectroscopy(XPS).At high F^(-)concentrations(C_(0)=5-1000 mg·L^(-1)),the amount of F^(-)adsorbed(Q_(F)),amount of hydroxidereleased by clay minerals,solution F^(-)concentration,andthe pH increase with increasing C_(0).The increases areremarkable at C_(0)>50 mg·L^(-1).The QF increases significantlyby continuously modifying the pH level.At C_(0)<5-100 mg·L^(-1),clay minerals adsorb H+to protonatealuminum-bound surface-active hydroxyl sites in thesuperficial layers and induce F^(-)binding.As the C_(0)increases,F^(-),along with other cations,is adsorbed toform a quasi-cryolite structure.At C_(0)>100 mg·L^(-1),newminerals precipitate and the product depends on the criticalAl^(3+)concentration.At[Al^(3+)]>10^(-11.94)mol·L^(-1),cryoliteforms,while at[Al^(3+)]<10^(-11.94)mol·L^(-1),AlF_(3) is formed.At low C_(0)(0.3-1.5 mg·L^(-1)),proton transfer occurs,andthe F^(-)adsorption capabilities of the clay minerals increasewith time.展开更多
The Rehai (Hot Sea) thermal field, being the strongest geothermal manifestation in the area, lies about 13 km southwest of Tengchong County. Most of its Tertiary granitic clasolites were intensely altered by the funct...The Rehai (Hot Sea) thermal field, being the strongest geothermal manifestation in the area, lies about 13 km southwest of Tengchong County. Most of its Tertiary granitic clasolites were intensely altered by the function of the acidic-neutral fluid ascending along the fault fissures. The most abundant altered minerals are kaolinites and illite-smectite (I-S) mixed layer minerals, the next are some alunite and silica minerals (hydrothermal quartz, chalcedony and opal), and a few chabazite and analcime are found. Zoning is a distinctive feature of the altered minerals at Rehai. This paper is mainly concerned with the hydrothermal clay minerals, the physical and chemical conditions prevailing during their formation, and the cause of zoning of the alteration.展开更多
基金supported by the National Natural Science Foundation of China(Grant number 42102145,41872148)the Science Foundation of China University of Petroleum,Beijing(Grant number 2462020BJRC005,2462022YXZZ007)+1 种基金AAPG Foundation Grants-in-Aid Program(Grant number 22108817)the Joint Fund of the National Natural Science Foundation of China(Grant number U19B6003-02-04).
文摘Shale contains a lot of clay minerals. Clay minerals mainly exist in nano- and micro-meter sized particles, and the pore structure is complex, which leads to its extremely complex wettability. The surface wettability of clay minerals significantly affects the oil and gas-bearing capacity of shale reservoirs. Therefore, studying the wettability of common clay minerals in shale at the nanoscale is of great significance for shale hydrocarbon exploration and development. In this study, the wetting behavior of water in n-hexane and toluene on different clay mineral surfaces at the nanoscale was systematically studied using Molecular dynamics (MD) simulation. And the influencing factors of wettability were analyzed. Through the analysis of the morphological changes of water, relative concentration of water, RDF and interaction energy, it is concluded that the following order of water wettability on the surfaces of clay minerals: montmorillonite > chlorite > kaolinite > illite. Through the analysis of interaction energy, it is concluded that the hydrophilicity of four clay minerals is stronger than that of lipophilicity. And the main interactions between water and oil and the mineral surfaces were van der Waals force and electrostatic force. In addition, the temperature, liquid hydrocarbon type, and mineralization of water affected the wettability of clay minerals. The concentration of water on the surfaces of montmorillonite, kaolinite, and illite decreased with increasing temperature, and the water wettability decreased. At 298 K, the hydrophilicity of the surfaces of the clay minerals in toluene follows the order montmorillonite > chlorite > kaolinite > illite. The higher the NaHCO3 concentration in water, the weaker the wettability of the clay mineral surfaces to water. By comparing the previous experimental results with the MD simulation results, similar wetting characteristics were obtained, and the reliability of the simulation results was verified. MD simulation was used to explore the water wetting of the surfaces of four clay minerals in a shale reservoir from the micro level. This makes up for the lack of experimental means for clarifying the flow and production mechanisms of shale oil and gas and effectively improves the evaluation technology of shale.
基金Supported by the National Key Research and Development Program of China (No.2019YFE0124700)the Scientific Research Foundation of the Third Institute of Oceanography+1 种基金MNR (No.2019026)the Marine Protected Areas Network in China-ASEAN Countries。
文摘Clay mineral composition represents an important tracer of sediment source area,migration processes,and paleoclimatic conditions.Clay mineral analysis was performed on 15 surface sediment samples collected from the coast of Chanthaburi,Thailand.Results show that the composition of clay minerals in the study area differs substantially from that in surrounding regions of the Gulf of Thailand.The clay minerals of the Chanthaburi coast are dominated by kaolinite(~56%),followed by smectite(~21%),illite(~14%),and low concentrations of chlorite(~8%).The average illite chemistry index and crystallinity are 0.93 and 0.32,respectively.Comparative analysis of the clay mineral composition of surface sediments in several typical areas around the Gulf of Thailand indicated that the clays of the Chanthaburi coast are mainly derived from parent rock weathering in the small watersheds of the Chanthaburi and Welu rivers and the surrounding islands.Terrestrial input from the northern coast of the Gulf of Thailand(excluding the Mekong River)was previously considered negligible;however,the present results indicate that such input has impact on the eastern Gulf of Thailand.The warm humid climatic conditions in Southeast Asia are the primary factors that affect the strong chemical weathering in the study area,followed by the nature of the parent rock.
基金supported by the National Natural Science Foundation of China(52174122,52074168)Excellent Youth Fund of Shandong Natural Science Foundation(ZR2022YQ49)+1 种基金Climbing Project of Taishan Scholar in Shandong Province(tspd20210313)Young Expert of Taishan Scholar Project in Shandong Province(tsqn202211150).
文摘Rheological mechanical properties of the soft rock are afected signifcantly by its main physical characteristics-clay mineral.In this study,taking the mudstone on the roof and foor in four typical mining regions as the research object,frstly,the clay mineral characteristic was analyzed by the X-ray difraction test.Subsequently,rheological mechanical properties of mudstone samples under diferent confning pressures are studied through triaxial compression and creep tests.The results show that the clay mineral content of mudstone in diferent regions is diferent,which leads to signifcant diferences in its rheological properties,and these diferences have a good correlation with the content of montmorillonite and illite-montmorillonite mixed layer.Taking the montmorillonite content as an example,compared with the sample with 3.56%under the lower stress level,the initial creep deformation of the sample with 11.19%increased by 3.25 times,the viscosity coefcient and longterm strength decreased by 80.59%and 53.94%,respectively.Furthermore,based on the test results,the damage variation is constructed considering the montmorillonite content and stress level,and the M–S creep damage constitutive model of soft rock is established.Finally,the test results can be ftted with determination coefcients ranging from 0.9020 to 0.9741,which proves that the constitutive relation can refect the infuence of the clay mineral content in the samples preferably.This study has an important reference for revealing the long-term stability control mechanism of soft rock roadway rich in clay minerals.
基金The National Natural Science Foundation of China under contract Nos 42276084 and 42176078the Special survey items of the China Geological Survey under contract Nos DD20190205 and DD20221710。
文摘The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud.From the inside to the outside,the grain size goes from fine to coarse.Aside from the“grain size effect”,hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements(REEs).Based on the grain size,REEs,and clay mineral composition of 300 surface sediments,as well as the sedimentary genesis,the northern ECS shelf is divided into three geochemical zones:southwestern Cheju Island Mud Area(ZoneⅠ),Changjiang Shoal Sand Ridges(ZoneⅡ-1),Sand Ridges of the East China Sea shelf(ZoneⅡ-2).The northern ECS shelf is mostly impacted by Chinese mainland rivers(the Changjiang River and Huanghe River),and the provenance and transport mechanism of sediments of different grain sizes is diverse.The bulk sediments come primarily from the Changjiang River,with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current,and less from Korean rivers.Among them,surface sediments in the southwestern Cheju Island Mud Area(ZoneⅠ)come mostly from the Changjiang River and partly from the Huanghe River.It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf,which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River.The Changjiang Shoal Sand Ridges(ZoneⅡ-1)were developed during the early-middle Holocene sea-level highstand.It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current,North Jiangsu Coastal Current,and Changjiang Diluted Water.The surface sediments mainly originate from the Changjiang River and Huanghe River,with the Changjiang River dominating,and the Korean River(Hanjiang River)influencing just a few stations.Sand Ridges of the East China Sea shelf(ZoneⅡ-2)are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene.The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River,with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents.
基金Supported by the China Ocean Mineral Resources R&D Association Project(Nos.DY135-S2-2-03,DY135-S2-2-01)。
文摘Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global oceans except in South Mid-Atlantic Ridge(SMAR)due to limited explorations.Thus,32 MS and 34 non-MS(NMS)samples were analyzed to clarify the distribution characteristics and mineral compositions of clay minerals.All the sediments were collected along the SMAR between 12°S and 27°S.After removal of organic matter and carbonate,clay fractions(<2μm)were investigated by Xray diffraction(XRD)analysis.Results show that clay mineral assemblages of surface MS consist dominantly of smectite,less abundant illite,chlorite,and kaolinite in average weight percentage of 30%,21%,18%,and 16%,respectively.On the other hand,clay mineral assemblages in the NMS consist mainly of illite,less abundant kaolinite,chlorite,and very scarce smectite in average weight percentage of 47%,29%,24%,and 0.2%,respectively.The clay fractions in MS are mainly composed of amorphous or poorly crystallized Fe/Mn oxyhydroxides,clay mineral,quartz,and plagioclase.However,the counterparts in the NMS are mainly composed of well-crystallized clay minerals,quartz,and plagioclase without the presence of Fe/Mn oxyhydroxides.It is suggested that most of the illite,kaolinite,and chlorite in both MS and NMS are likely aeolian dust in origin from South Africa continent.In addition,the abundance of kaolinite dominates the clay mineral assemblage at low latitudes,where the intensive chemical weathering of continental source rocks facilitating the formation of kaolinite.In terms of smectite,it is indicated of authigenic origin in consideration of only smectite is available in several MS and the absence in NMS.Moreover,the MS samples with only smectite available are always accompanied by goethite.Therefore,it is assumed that most of smectite occurred in studied area is the results of interaction between hydrothermal Fe-oxyhydroxide,silica,and seawater.
基金granted by Petro China Innovation Foundation(Grant No.2019D-5007-0214)the National Mega Project of Oil and Gas(Grant No.2017ZX05013005-009)。
文摘The micro-nano pore structure of conglomerate in the Lower Karamay Formation of the Xinjiang Oilfield,Junggar Basin,northern China is characterized to predict its impact on fluid reserves and seepage.Authigenic clay minerals are mainly kaolinite(67%),followed by an illite/smectite mixed layer(18%),illite(10%),and chlorite(5%).For kaolinite,pore throats between 0–200 nm are dominant,accounting for 90%of the total pore throats.For illite/smectite mixed layer,pore throats also between 0–200 nm account for nearly 80%,while pore throats between 200-500 nm only account for 15%.For illite,pore throats below 100 nm account for about 80%,while pore throats in the range of 100–500 nm only account for 20%.For chlorite,most throats are below 200 nm.The pore roundness of illite is the highest,while the pore roundness of chlorite is relatively lower.The lower limits of the dynamic and static pore throat radii are 42.128 nm and 72.42 nm,respectively.The theoretical contribution rates of the illite/smectite mixed layer,kaolinite,illite and chlorite to storage/seepage are 60%/45.86%,52.72%/38.18%,37.07%/28.78%and 32.97%/26.3%,respectively.Therefore,the contribution rates of clay minerals in the study area are as follows:illite/smectite mixed layer,kaolinite,illite and chlorite.
基金financed by the National Youth Sciences Foundation of China (No. 41502044)
文摘The role of authigenic clay growth in clay gouge is increasingly recognized as a key to understanding the mechanics of berittle faulting and fault zone processes,including creep and seismogenesis,and providing new insights into the ongoing debate about the frictional strength of brittle fault(Haines and van der Pluijm,2012).However,neither the conditions nor the processes
基金supported by the National Natural Science Foundation of China(Nos.41706074,41706092,41506107)the Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology(No.MGQNLM201902).
文摘Studying the sedimentary characteristics of the muddy area along the Yellow Sea shelf is of great significance for deep-ening the understanding of the climate and environment evolution since the last glacial period.Recently,a small muddy area developed in the southern Weihai offshore has attracted a lot of attention.Based on high-resolution grain size,clay mineral,AMS14C,and OSL data of sediments from the core WHZK01 in the muddy area,we acquired a new understanding of sedimentary characteristics,sources and paleoclimatic environment during the last 13 kyr.The results show that the core WHZK01 sediments were mainly from the Yellow River and local rivers along the coast.However,the sources varied for different deposition units.The riverbed(before 13 kyr BP)and fluvial plain deposits(13-10 kyr BP)were mainly from local river inputs.The very thin littoral deposits from 10 kyr BP to 8 kyr BP also mainly originate from coastal river inputs,while the littoral-neritic deposits since 8 kyr BP were dominated by the Yellow River materials and partly supplied by the coastal rivers and the island erosion.In addition,five events related with the strong East Asian winter monsoon(EAWM)during the intervals of 13.0-11.0 kyr BP,10.0-8.2 kyr BP,7.0-5.0 kyr BP,3.5-2.5 kyr BP,and 1.2-0.5 kyr BP were iden-tified.Three events related with the enhancement of the EAWM since the middle Holocene have strengthened the transport capacity of the coastal currents of the Shandong Peninsula.Meanwhile,more Yellow River-derived distal sediments were deposited to the southern Weihai offshore and formed wedge-shaped muddy bodies.In short,the ratio of smectite/illite could be used as an effective EAWM indicator since 13 kyr BP on the northwestern shelf of the South Yellow Sea.
文摘The kinetics of Cu ion exchange on Na-montmorillonite clay mineral has been investigated at three temperatures, in three solvents: H2O, ethylene glycol and glycerol. Solvent effects on the reaction rate have been discussed. The thermodynamic activation parameters were calculated and discussed in terms of solvation effects. The determined isokinetic temperature indicates that the reaction is enthalpy controlled where the interaction between solvent and clay surface plays an important role. A reaction mechanism which describes the solvent effect on the rate of Cu ion exchange is proposed.
文摘The thermal properties such as specific heat capacity and heat dissipation of peloids play an important role in therapeutic applications. Therefore, these properties were determined on the peloids samples taken from spas where peloid applications are used in Turkey. In addition, some pure clay minerals were investigated to determine their suitability as possible constituents of therapeutic peloids and to make recommendations for preparing the most usable peloids for thermal therapy. For this aim, the mineralogical and thermal properties of samples were investigated using X-ray diffraction (XRD) and Differential Scanning Calorimeter (DSC). The mineralogical compositions of the peloid samples are not homogenous, and their clay mineral content is approximately 60%, and the most abundant clay mineral is calcium montmorillonite. The cooling time of peloids are between 20 and 25 minutes, which is suitable for therapy and thus these peloids are suitable for using in health problems requiring heat treatment. The samples have favorable heat dissipation capacity and partially cooling kinetics. Specific heat capacity of the peloid samples is partially appropriate for heat therapy and these values range from 0.60 to 1.41 J/g·°C, and partially high in peloids with high smectite content. The pure sepiolite samples have higher heat dissipation properties than those of other clay minerals especially illites and kaolinites. Ca-montmorillonite and kaolinite have the lowest specific heat values while sepiolite samples have higher values. Sepiolite and partly Na-Ca-montmorillonite are more appropriate than the other studied clay minerals as a peloid constituent especially for therapy of musculoskeletal pain.
基金supported by the National Natural Science Foundation of China(Grant Nos.42125602,42076052)the National Key Research and Development Program of China(Grant No.2022YFF0800503)+3 种基金the Strategic Priority Research Program of CAS(Grant No.XDB40010100)the Marine S&T Fund of Shandong Province for QNLM(Grant No.2022QNLM050203)the Innovation Project of QNLM(Grant No.MGQNLM-KF202001)the Taishan and Aoshan Talents Program(Grant No.2017ASTCP-ES01).
文摘As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolian dust transported eastward from the Asian interior.Clay minerals,as the major fine-grained weathering products of continental rocks,can be readily transported by wind or currents over long distances and thus have been widely used in the reconstruction of paleoclimate and weathering history.However,the overall evolutionary tendency and response mechanism of clay mineral records over large spatial and long timescales across Asia remain unclear.Here,two continuous and high-resolution clay mineral records since 30 Ma were reconstructed from sediments at Deep Sea Drilling Program(DSDP)Sites 292 and 296 in the Philippine Sea.Clay minerals and Sr-Nd isotope compositions were used to constrain provenance and reconstruct the drying history of the dust source region since the Oligocene.The results show that the clay-sized detrital sediments in the Philippine Sea are a mixture of Asian eolian dust and volcanic materials from the West Pacific arcs.Based on the clay mineral compositions and eolian flux,we reveal that the Asian interior has been continuously drying since the late Oligocene and that stepwise enhanced aridification occurred at approximately 20,14,7,and 3 Ma.Compared with other regions of the world,the relative contents of illite and chlorite increased more dramatically in Asia during the late Cenozoic,and the inconsistency became more obvious at approximately 20 Ma.Since 3 Ma,illite and chlorite have increased consistently across the globe.Combined with the Asian tectonic and climatic history,we suggest that the increase in illite and chlorite from Asia between 20 and 3 Ma was mainly in response to the uplift of the Himalayan-Tibetan Plateau,whereas after 3 Ma,it was primarily controlled by global cooling driven by the expansion of the Arctic ice sheet.
基金CGG Robertson provided collaborative funding by conducting QEMSCAN?,SEM and thin section analyses for the project。
文摘Analyses of clay minerals within the Early Cretaceous Weald Basin,Southeast England reveal kaolinite,illite and chlorite as the main detrital clay minerals while glauconite and smectite are subordinates.A kaolinite-rich assemblage which characterized the sand-dominated Ashdown and Tunbridge Wells Sand formations and an illite-dominated assemblage associated mostly with the Wadhurst Clay and Weald Clay formations are recognized.Kaolinite was enriched in the Ashdown and Tunbridge Wells Sand formations during warm and humid climate with high precipitation that encouraged chemical weathering and leaching,while cold and dry conditions favoured the concentration of illite in the Wadhurst Clay and Weald Clay formations.Rainfall patterns associated with warm climate were drastically reduced during the drier climatic conditions.Most clay minerals are detrital in origin,with chlorite being more prominent than previously recognized.Contrary to previous studies and assumptions,this study revealed that authigenic clay minerals are present in the Hastings Beds,with vermiform and mica-replacive kaolinite being the most common,consistent with humid depositional environments.Isolated authigenic illite is also present,along with a chloritized grain,providing evidence for mesodiagenesis.The absence of dickite and occurrence of kaolinite,suggest that authigenic illite formed in relatively shallow burial conditions,indicating a maximum burial depth of2500 m-3000 m,about 1000 m deeper than previous estimates of 1500 m-2000 m.Authigenic clay minerals are absent in the Weald Clay Formation possibly because of hindered flow of meteoric water and limited growth space for authigenic minerals.This study is significant in:1)reinforcing multiple methods to facilitate a robust and balanced knowledge of formation and transformation of clay minerals;2)investigating detrital and authigenic clay mineral assemblages when assessing the palaeoenvironments of sedimentary basins.
基金This work was supported by the National Natural Science Foundation of China(21976054)the National Key Research and Development Program of China(2017YFA0207002)Beijing Outstanding Young Scientist Program.
文摘Aluminosilicate clay mineral(ACM)is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring.In past two decades,in-depth understanding on unique layered structure and abundant surface proper-ties endows ACM in the emerging research and application fields.In field of solar-chemical energy conversion,ACM has been widely used to support various semiconductor photocata-lysts,forming the composites and achieving efficient conversion of reactants under sunlight irradiation.To date,classic ACM such as kaolinite and montmorillonite,loaded with semi-conductor photocatalysts has been widely applied in photocatalysis.This review summaries the recent works on ACM-based composites in photocatalysis.Focusing on the properties of surface and layered structure,we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM,i.e.,type 1∶1 and type 2∶1.Not only large surface area and active surface hydroxyl group assist the substrate adsorption,but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts.Besides,we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process.This review could inspire more upcoming design and synthesis for ACM-based photocatalysts,leading this kind of economic and eco-friendly materials for more practical application in the future.
基金Project supported by the National Natural Science Foundation of China(51872269,42072053)。
文摘The unique luminescent performance of lanthanide complexes/clay minerals hybrid materials has been fascinating many researchers for recent decades.It not only retains the excellent luminescent characteristics of lanthanide complexes but also improves the poor stability of the complexes.In this article,we introduce the luminescence mechanism of lanthanide complexes and point out the necessity of their combination with clay minerals.After the analysis of the structure and interlayer environment differences of 1:1-type and 2:1-type clay minerals,the intercalation methods(covalent grafting and ion exchange)appropriate for different clay minerals are summarized with examples.Based on the luminescence characteristics of the hybrid materials,the applications of these materials as luminescent probes in recognition of specific metal cations and molecules,detection of pH value,and temperature are reviewed.Finally,the current problems in the preparation of lanthanide complexes/clay minerals hybrid luminescent materials and shortcomings that need improvement in their performance are analyzed,and the application prospect is forecast.
文摘Greenish clays often occur as thin layers in Early Cretaceous shallow-water carbonatesediments of Istria where they mark the top of fining upwards sequences. When they showevidence of subaerial exposure and pedogenesis they are considered paleosols. The claymineralogical composition is as follow: (1) randomly oriented I/S mixed layer, (2) regularlyoriented I/S mixed layer, (3) illitic material, (4) kaolinite and (5) chlorite. The insoluble limestoneresidue situated immediately below the greenish clays is dominated by smectite, and also containskaolinite and illitic material. The very high smectite content in the insoluble residue is probablythe result of additions of volcanic dust during carbonate sedimentation. That clay mineralcomposition in the pelitic material clearly indicates the influence of both pedogenic and diageneticprocesses. It may also indicate additional volcanic dust contribution before and during thesubaerial exposure.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41272053 and 41472041).
文摘Crystallinity,polytype,and morphology of clay minerals in the Luochuan loess-palaeosols in Shaanxi Province,northwest China were studied in order to have an insight into their origin using X-ray diffraction(XRD)analysis and scanning electron microscopy(SEM)methods.The SEM observations showed that the morphology of some illites seems to be lath-shaped crystals.An analysis of illite crystallinity(IC)on the Luochuan section indicated that the origin of illite was related to the rocks of an anchizone.Most illite in the Luochuan loess-palaeosol section were of 2M1 polytype,but some were of 1M polytype formed by weathering of feldspar in the process of pedogenesis.Illite in the Luochuan section has undergone both physical and chemical weathering.These results revealed that most illite were of detrital origin related to the source area of an anchizone,but parts of the illite were of an authigenic origin formed during pedogenesis after sedimentation.Chlorites in the samples of the Luochuan section were mainly composed of irregular flaky grains and their crystallinity was good.These showed that chlorite had the detrital origin formed by physical weathering.Kaolinite crystallinity was relatively good.The value of CIA on the Luochuan section ranges from 61.9 to 69,and therefore kaolinite could not be formed during weathering and pedogenesis.These results indicated that the kaolinite had a detrital origin.Morphology of smectite seems to be capillaceous.The XRD patterns of all samples contained diffraction peaks at 1.5218Å(nontronite)and 1.5052Å(montmorillonite),thus indicating an intermediate composition between trioctahedral and dioctahedral smectite.The smectite crystallinity was very poor.These results revealed that smectite in the study area was authigenic rather than detrital origin.
基金supported by the National Natural Science Foundation of China(Grant Nos.41888101,41690111,41991320&41920104005)。
文摘Obtaining a continuous sedimentary record of Cenozoic East Asian paleoclimate change is key to understand the origin,evolution and driving mechanism of the East Asian monsoon and climate change.Based on the continuous Cenozoic fluvial and lacustrine sedimentary sequence in the Weihe Basin,central China,we carried out research on the content and crystal parameters of clay minerals.The paleoclimate change since the middle Eocene was reconstructed accordingly.The results show that smectite and illite are the dominant clay minerals in fluvial-lacustrine sediments of Weihe Basin.The crystallinity of illite,the chemical index of illite,the ratio of smectite to illite and chlorite decrease gradually,which indicates that chemical weathering in the Weihe River watershed stepwise weakened since the middle Eocene,under the background of a semi-arid and semi-humid climate.The formation of palygorskite may be affected by a weak diagenesis.In this case,the content of smectite and the illite crystallinity caused by the weathering in the corresponding period may be actually higher than that of the current,which indicates that the climate in the Weihe Basin region was relatively warm and humid from the middle Eocene to Pliocene.With the decrease of Cenozoic global temperature and the continuous accumulation of sediments,the intensity of chemical weathering in the Weihe Basin gradually weakened,and the East Asian monsoon climate gradually evolved until becoming dry in the Quaternary.Evidence from clay minerals also indicates that the aridification in the Weihe Basin from the late Eocene to the Oligocene may be a response to the global cooling event at the Eocene-Oligocene transition.
基金supported by the National Key Research and Development Program of China (Grant No. 2018YFE0202402)the Shanghai Science and Technology Innovation Action Plan (Grant No. 20590780200)the National Natural Science Foundation of China (Grant Nos. 41530964 & 41942046)
文摘The Middle Miocene Climate Transition(MMCT,~14 Ma)is the largest cooling event in the Cenozoic“Coolhouse”,which significantly impacts the global chemical weathering pattern.In this paper,the responses of the MMCT global cooling event in the deep South China Sea were studied by clay mineral assemblages analysis of the oceanic red beds(ORB)at International Ocean Discovery Program(IODP)Expedition 368 Site U1502.The results show that the clay mineral assemblages of the ORB at Site U1502 are mainly composed of smectite(56–88%),illite(7–29%),and kaolinite(6–20%),without chlorite.The contents of these clay minerals and illite crystallinity show a four-stage variation pattern during early-middle Miocene(22.8–10.8 Ma).Smectite decreased from average 81%during 22.8–16.2 Ma and 16.2–14.4 Ma to average 67%during 13.8–10.8 Ma,with a rapid decrease of~14%during 14.4–13.8 Ma.On the contrary,illite and kaolinite increased rapidly by~8%and~6%,respectively,during 14.4–13.8 Ma.Illite crystallinity increased from average 0.18°Δ2θduring 22.8–16.2 Ma to average 0.19°Δ2θduring 16.2–14.4 Ma,and then decreased rapidly by~0.02°Δ2θduring 14.4–13.8 Ma.The provenance analysis of clay minerals shows that illite and kaolinite mainly originated from South China landmass due to physical erosion,while smectite mainly came from the Luzon arc as the product of chemical weathering.Therefore,smectite/illite ratio and illite crystallinity are used as proxies of chemical weathering intensity in the early-middle Miocene.High values of the ratio and the crystallinity represent the enhanced chemical weathering,whereas low values indicate the weakened chemical weathering or the strengthened physical erosion process.The smectite/illite ratio and illite crystallinity both decreased rapidly during 14.4–13.8 Ma,indicating the chemical weathering in the surrounding area of the South China Sea weakened rapidly,which we believe is the result of the MMCT event forcing.In addition,their values increased slightly during 16.2–14.4 Ma,which is in response to the relatively enhanced chemical weathering during the Middle Miocene Climate Optimum(MMCO).The variation pattern of clay mineral assemblages of the early-middle Miocene ORB in the South China Sea and its rapid transformation during the MMCT reveal that the Cenozoic cooling played a specific role in controlling the chemical weathering of the Earth’s surface.
基金This work was supported by the National Natural Science Foundation of China(Grant No.40601004).
文摘This research investigates the adsorptionmechanisms of fluoride(F)on four clay minerals(kaolinite,montmorillonite,chlorite,and illite)underdifferent F^(-)concentrations and reaction times by probingtheir fluoride superficial layer binding energies and elementcompositions using X-ray photoelectron spectroscopy(XPS).At high F^(-)concentrations(C_(0)=5-1000 mg·L^(-1)),the amount of F^(-)adsorbed(Q_(F)),amount of hydroxidereleased by clay minerals,solution F^(-)concentration,andthe pH increase with increasing C_(0).The increases areremarkable at C_(0)>50 mg·L^(-1).The QF increases significantlyby continuously modifying the pH level.At C_(0)<5-100 mg·L^(-1),clay minerals adsorb H+to protonatealuminum-bound surface-active hydroxyl sites in thesuperficial layers and induce F^(-)binding.As the C_(0)increases,F^(-),along with other cations,is adsorbed toform a quasi-cryolite structure.At C_(0)>100 mg·L^(-1),newminerals precipitate and the product depends on the criticalAl^(3+)concentration.At[Al^(3+)]>10^(-11.94)mol·L^(-1),cryoliteforms,while at[Al^(3+)]<10^(-11.94)mol·L^(-1),AlF_(3) is formed.At low C_(0)(0.3-1.5 mg·L^(-1)),proton transfer occurs,andthe F^(-)adsorption capabilities of the clay minerals increasewith time.
文摘The Rehai (Hot Sea) thermal field, being the strongest geothermal manifestation in the area, lies about 13 km southwest of Tengchong County. Most of its Tertiary granitic clasolites were intensely altered by the function of the acidic-neutral fluid ascending along the fault fissures. The most abundant altered minerals are kaolinites and illite-smectite (I-S) mixed layer minerals, the next are some alunite and silica minerals (hydrothermal quartz, chalcedony and opal), and a few chabazite and analcime are found. Zoning is a distinctive feature of the altered minerals at Rehai. This paper is mainly concerned with the hydrothermal clay minerals, the physical and chemical conditions prevailing during their formation, and the cause of zoning of the alteration.
