ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on th...ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on their formation mechanism.展开更多
It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-cru...It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-crustal evolution of the ophiolites are undergoing significant changes with the formation of peculiar(on structure and composition)rocks,sometimes with unusual mineral paragenesis.The presence of such rocks in mélange tectonic zones greatly complicates to determine their origin.In the Ural folded belt(length more than 2,000 km)separating the East European Platform and the West Siberian sedimentary basin,ophiolites are widespread forming a chain of mafic-ultramafic massifs(Fig.1)located in the allochthonous position with mélange at the bottom(Puchkov,2013).With the Urals ophiolites are associated occurrences of eclogites,jadeites,ruby and other rocks of unclear nature,sometimes regarded as potentially diamondiferous.Such formations of unclear genesis include the associating with ophiolites metabasites of higher alkalinity composing the body in the mantle peridotites of the mélange Main Uralian Fault(MUF)zone(Shmelev,2005).By this time they are determined in different parts of the fault zone,but most completely are known in the Sub Polar Urals,where are distinguished under the name of Sertynya alkaline-ultramafic complex,which is located just 25 km east of Hartes kimberlitic complex(Fig.1).Formally,its affiliation to diamond-bearing associations is confirmed by finding of grains and fragments of natural diamond in the weathering crust.A detailed study of the rock complexes shows that in reality they have a polygenic nature,combine theelements of proper magmatic and fluidizate-explosive formations,the appearance of which was interfaced with the processes at the slab-mantle wedge boundary in subduction zones.Polygenic nature of the rocks is reflected in the existence of three interrelated structural-geological units:(1)bodies and dikes of uniformmetadiabasesanddensefine-grainedmetadolerites(lamprophyres),(2)fluidal-brecciated dolerites('tuff breccias')and(3)structural weathering crust with angular or rounded fragments(blocks)of metadolerites and serpentinites.The rocks have experienced rodingitization and permeated with net of veins a vesuvianite composition.The host peridotite matrix(harzburgites and dunites)has undergone serpentinizationandchloritization.Structural relationships give grounds for distinguishing in the history of the complex formation the magmatic proper(dolerite dyke and lamprophyre intrusion)and infiltration fluidizate-explosive(metasomatic transformation of dolerite)stages.Peculiarities of petrography and mineralogy of rock complexes does not allow to compare them with lamproites and kimberlites.Metadiabases demonstrate relics of ophitic structure,as primary paragenesis is completely replaced by aggregate of chlorite,zoisite and leucoxene.Dolerites(lamprophyres)have a uniform fine-grained or porphyry structure with phenocrysts of clinopyroxene,brown amphibole and leucoxene(sphene),which are immersed in a fine-scaly aggregate of light green mica.In the rocks amphibole,garnet and vesuvian are present.Clinopyroxene corresponds to augite with moderate content of titanium and alumina(up to 3.5wt.%),showing a normal magmatic zonation in composition.Mica previously wrongly called as phlogopite,actually has an extremely ferrous composition and corresponds to biotite(annite).Amphibole is presented by magmatic titaniferous tschermakite hornblende and metamorphic(bluish)variety of sodium-calcium composition(taramite).Garnet is presented by exceptionally grossular of rodingite type.Mineralogy of weathering crust reveals similar features,but in the samples it is marked the presence of muscovite,orthoclase and weakly ferrous diopside.An important feature of the weathering crust is the presence of shear surfaces on minerals,resulting in fracturing due to internal stress,confirming the explosive nature of protolith.The bulk chemical composition of rocks is characterized by significant variations in the content of silica(30-46 wt.%)and alkalis(0-6.5 wt.%).These metabasites have consistently a low magnesia number and high titanium oxide content(1.5-3.0 wt.%).Side by side with these are been established the uniform slope REE distribution trends similar to the trend of oceanic basalts N-MORB type(Fig.2).The level of trace element compositions does not depend on variations in the alkalinity of the rocks,but clearly correlates with the titanium content.Unlike them the Hartes kimberlites demonstrate the distribution with deficit of HREE,andthe level of the elements content is correlated with the alkalinity of rocks(Mahotkin et al.,1998).Another important geochemical feature of the Sertynya complex rocks is a regular behavior of the mobile LILE elements(Cs,Rb,Ba,K).In the varieties of rocks with mica enriched by alkalis,it is recorded extremely high level of LILE,exceeding the level of contents in N-MORB basalts at 10-10000 times!In the metabasites varieties with low level of alkalinity,LILE content is sharply(except Cs)reduced to minimum values(Fig.2).The observed pattern of the element distribution is undoubtedly the result of postmagmatic fluid-metasomatic alteration of the original rocks.Tectonic position and the primary composition characteristics of the metadolerites give reason to consider them as fragments of the ophiolite sheeted dike complex(Shmelev,2005).The famous dike complexes in the ophiolite massifs of the MUF zone(east of mélange)belong to suprasubduction formations of Paleozoic age.However the obtained mainly ancient U-Pb zircon dating(up to Archean inclusive)for metadolerites of the Sertynya complex,make it possible to assume its Vendian-Early Cambrian(530-617 Ma)age.It permits to compare the Sertynya metabasites with the Vendian metaophiolites of the MUF zone in the Middle Urals(Petrov et al.,2010).It is noteworthy that similar age datings(520-550 Ma)are also established for kimberlites of the Hartes complex located to the west of ophiolites.Therefore,thepresenceofthe Vendian-Cambrian ophiolite of MOR-type in the MUF mélange zone,'changing'to the east of Ordovician ophiolites SSZ-type,seems quite possible.The obtained data allow to suggest an original interpretation of nature of the Urals fluidizate-explosive formations considering the process specifics in the subduction zones(Bebout and Barton,2002).Accordingto this model,the pre-Ordovician(?)oceanic crust has undergone transformations and deformations on the slab-mantle wedge boundary during the subduction.As a result of slab dehydration it occurred a flow of aqueous fluids,which were enriched with the extracted from sedimentary rocks the LILE elements and percolated through the mantle substrate with dolerite dyke complex.Interaction with them led to the formation of chlorite-zoisite and/or mica(biotite-bearing)fluidizates and in the presence of a gas phase-fluidizate-explosive breccias with subsequent development of weathering crust.In the surrounding peridotites an explosive process is marked by the formation of pseudokimberlite breccias.Fluidized-explosive occurrences in mantle peridotites of mélange zones should be considered as indicators of the subduction slab-mantle interaction at relatively shallow levels involving enriched LILE fluids(without melts participation),rising as the front from the subduction zone.In this interpretation,there is no need toappealtothealkaline-ultramaficor lamproit-kimberlite hypothesis of the genesis of these formations,however,the question of their potential diamondiferous remains to be open.The proposed interpretation of the fluidizate-explosive occurrences makes it possible to comprehendthat in reality the mélange is a complex formation with signs of not onlycollisional(as usually is considered),but also of earlier subduction events.展开更多
Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bod...Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bodies of various compositions.All units contain a variety of ore mineral deposit types and their surrounding zones of hydrothermal alteration.Continued geological and metallogenic researches in the past 30 years have led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.Oldest magmatism comprises Early Jurassic events,related to extensional tectonism,which ranged from rhyolitic,through dacitic and andesitic,and to basaltic magma.Additional extensional processes(in Bajocian)were characterized by intrusion of a gabbro and diorite dike system into recently deposited late Early Jurassic-early Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Related intense hydrothermal activity was responsible for important polymetallic mineralization,with more than 100 recognized outcropping ore occurrences.A detailed study of 11 of these ore occurrences has indicated anomalous concentrations of gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant ore mineral occurrences were discovered.展开更多
The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission ...The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer. And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A, HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperature hydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.展开更多
The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in ...The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in oil or water. Based on the production test data of exploratory wells in the Tazhong uplift of the Tarim basin, this paper discusses in detail the differences in occurrence and distribution featrues between the surface and underground natural gases; presents a restoration of the surface gas occurrence to actual underground geologic conditions according to the dissolubility of natural gas under different temperature, pressure and medium conditions; and classifies the natural gas into three states, i.e. the oversaturated, saturated and undersaturated, according to its relative content underground. Through a comparative analysis of the differences in surface and underground occurrences of natural gas, it discusses the hydrocarbon reservoir formation mechanism and distribution rules, thereby providing guidances as new methods and technologies for the prediction of potential natural gas reservoir distribution in the study area.展开更多
The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analy...The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analysis,field emission scanning electron microscopy,energy dispersive spectrometer,and automatic mineral analysis software.Results identified that 91.69%of ThO2 in the combined samples was mainly distributed in rare earth minerals(bastnaesite,huanghoite,monazite;56.43%abundance in the samples),iron minerals(magnetite,hematite,pyrite;20.97%),niobium minerals(aeschynite;14.29%),and gangue minerals(aegirine,riebeckite,mica,dolomite,apatite,fluorite;4.22%).An unidentified portion(4.09%)of ThO2 may occur in other niobium minerals(niobite,ilmenorutile,pyrochlore).Only a few independent minerals of thorium occur in the iron ore samples.Thorium mainly occurs in rare earth minerals in the form of isomorphic substitution.Analyses of the geochemical characteristics of the major elements indicate that thorium mineralization in the Main Ore Body was related to alkali metasomatism,which provided source material and favorable porosity for hydrothermal mineralization.Trace elements such as Sc,Nb,Zr,and Ta have higher correlation coefficients with thorium,which resulted from being related to the relevant minerals formed during thorium mineralization.In addition,correlation analysis of ThO2 and TFe,and REO and TFe in the six types of iron ore samples showed that ThO2 did not always account for the highest distribution rate in rare earth minerals,and the main occurrence minerals of ThO2 were closely related to iron ore types.展开更多
A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent mi...A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent minerals in nature and occasionally as ion adsorption, isomorphous or amorphous silver minerals. Nearly 190 silver minerals have been discovered in China. Their shapes, constituents, textures, grain sizes, embedded types, distribution patterns, mineral assemblages and metallogenic series suggest that these characteristics are closely related to geneses of deposits and dependent of ore-forming conditions. Pb, Zn and Cu sulphides are the main carrier minerals of silver. The partition of silver in ore is constrained by the mineralization intensity, grain size and embedded form of silver minerals and mineral assemblages.展开更多
The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E...The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E) and its adjacent area up to 1991 were analyzed systematically.These earthquakes are called as strong earthquakes and those of the east before and after 1600,and those of the west before and after 1900, are called respectively as former ones and latter ones.Most of these events were divided into 45 sets of which the each relatively concentrated in both time and space and took the form of group.In the grouping form,the probability of occurrence of a strong earthquake higher than the average appeared simultaneously in time and space.The grouping occurrences of the strong earthquakes of Chinese mainland has been determined as a fundamental feature of the seismicity.展开更多
This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four k...This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four kinds of diseases as well as the coping strategies of people in the area.We collected the rainfall and temperature data of Lokoja City during 2000-2020 from the National Aeronautics and Space Administration(NASA),and the medical records data of the four kinds of diseases from the Kogi State Ministry of Health.We also conducted a semi-structured questionnaire of 250 residents,who have experienced one of these diseases,to investigate their coping strategies with these diseases.The Pearson correlation and multiple regression analysis were used to research the relationship between the climate parameters and cases of diseases.The result showed annual variations in climatic parameters with R^(2)values of 0.0557,0.0009,and 0.4915 for rainfall,maximum temperature,and minimum temperature,respectively.A positive and significant relationship were observed between maximum temperature and malaria(r=0.80),rainfall and malaria(r=0.54),minimum temperature and meningitis(r=0.64),as well as rainfall and cholera(r=0.66)at P<0.05 level.For the regression analysis R^(2)=0.71,0.50,and 0.52 for malaria,cholera,and meningitis,respectively at P<0.05 level.During 2000-2020,cases of malaria were highest in Ward A with 15,422,while 715 cases of pneumonia were highest in Kupa North Ward.In Ward A,3787 cases of cholera were recorded to be the highest,while cases of meningitis were highest in Kupa North Ward with 2383 cases.Investigation revealed that malaria is more common in the wet season,while cholera and meningitis cases were highest in the dry season.The study revealed that the most practiced coping strategy is the use of medications by about 90%of the respondents.More studies are recommended in the study area to establish a causal link between climate change and disease occurrence,and intervention from government in form of prevention and control programmes should be vigorously implemented.展开更多
This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) a...This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.展开更多
Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical compos...Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical composition of uranium minerals within CD were investigated by using scanning electron microscope and electron microprobe analyses.The results show that uranium minerals mostly occur in cell pores in the forms of fructus aurantia and concentric band structure.Pitchblende and coffinite are the main uranium minerals,and the former is dominant.According to the crystal morphology and composition of trace elements of uranium minerals,uranium precipitation on the pores is grouped into two periods,orderly Ⅰ,Ⅱ.Moreover,the Ⅰ period is further divided into two sub-period,orderly Ⅰ_(1),Ⅰ_(2).Moreover,askew sphere uranium minerals could indicate fluid migration.Under certain geological environment condition,uranium is unevenly adsorbed on the surface of the pore by the Van der Waals(i.e.,Ⅰ_(1) period),and then is precipitated towards to the center of the pore until the whole pore is filled up with uranium minerals by complicated process such as microorganism activities(i.e.,Ⅰ_(2),Ⅱ period).It will provide some guidance for studying the metallogenic environment and genesis of sandstone-type uranium deposit.展开更多
This paper takes the water body of Daliao River-Liaodong Bay as the research object,divides it into three regions:river,estuary,and offshore,and analyzes the changes of antibiotics and antibiotic resistance genes(ARGs...This paper takes the water body of Daliao River-Liaodong Bay as the research object,divides it into three regions:river,estuary,and offshore,and analyzes the changes of antibiotics and antibiotic resistance genes(ARGs)from inland rivers to the sea and the environmental impact factors from this perspective.The results showed that in general,the pollution of antibiotics and ARGs in Daliao River-Liaodong Bay belonged to the medium-low level,and levels of antibiotics and ARGs were nd–106.23 ng/L and nd–1.95×10^(8)copies/L,respectively.The concentrations and types of antibiotics and ARGs decreased from inland to sea regions.Analysis of the distributional characteristics of antibiotics and ARGs from a regionalized perspective revealed significant differences among the three regions in sulfonamide antibiotics,tetracycline antibiotics,and dominant ARGs.Sulfonamide antibiotic levels were significantly higher in the estuarine zone than in the riverine and offshore zones;tetracycline antibiotic levels were significantly higher in the riverine and estuarine zones than in the offshore zone.Aminoglycosides were dominant in the riverine and estuarine zones,and macrolides were dominant in the offshore zone.We characterized the effects of environmental factors on the assignment of antibiotics and ARGs and found that overall temperature contributed the most to variation in antibiotics and ARGs;the contribution of dissolved oxygen was the lowest.The estuarine zone was most affected by these factors,followed by the offshore zone and finally the riverine zone.展开更多
This paper presents an overview of the pathogens, symptoms of damage, patterns of occurrence, and chemical control methods associated with four major pear tree diseases: pear scab, pear ring rot, pear anthracnose, and...This paper presents an overview of the pathogens, symptoms of damage, patterns of occurrence, and chemical control methods associated with four major pear tree diseases: pear scab, pear ring rot, pear anthracnose, and pear speckle. The objective is to provide valuable references for the scientific and precise prevention and management of diseases in pear orchards, thereby contributing to the production of high-quality and high-yield pear fruits.展开更多
Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by clima...Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.展开更多
The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the...The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the pore system of alkaline lake shale,which restricts the efficient exploration and development of shale oil.This study investigates the Fengcheng Formation shale in the Mahu sag of the Junggar Basin,employing methods such as low-temperature nitrogecn adsorption(LTNA),mercury intrusion capillary pressure(MICP),and nuclear magnetic resonance(NMR)to quantitatively characterize the multi-scale pore structure and fractal characteristics of shale,while evaluating the applicability of these methods.Based on a comprehensive analysis of material composition,different pore types,and fractal dimensions,the controlling factors for the development of different pore types and their seepage capacity are discussed.The results indicate that inorganic mineral pores are the main development in alkaline lake shale,with the pore morphology being characterized by slit-like and ink-bottle shapes.The multi-scale pore size distribution(PSD)shows that Ⅱ-micropores(10-100 nm)and mesopores(100–1000 nm)are the main contributors to the pore system.The development of Ⅱ-micropores is associated with feldspar and calcareous minerals,the development of Ⅰ-micropores(<10 nm)and mesopores is related to quartz content,while large pores are mainly found in interlayer fissures of clay minerals.The development of Ⅰ-micropores increases the roughness of pore surface and enhances the adsorption capacity of the pores,while the development of Ⅱ-micropores associated with calcareous minerals hinders pore seepage capacity.Mesopores and macropores(>1000 nm)exhibit good flowability.The high content of siliceous minerals plays a positive role in the pore system of alkaline lake shale.The shale with higher fractal dimension Dmin exhibits greater adsorption capacity,which hinders the accumulation of free-state shale oil.Different types of pore space play different roles in the occurrence of shale oil,with free-state shale oil primarily occurring in micro-fractures and inorganic mineral pores,and the pore size is exceeding 10 nm.展开更多
Centering on the critical bottlenecks in the development of shale oil in the Jiyang Depression of Shengli Oilfield,key scientific and engineering issues are proposed in aspects such as the storage space and occurrence...Centering on the critical bottlenecks in the development of shale oil in the Jiyang Depression of Shengli Oilfield,key scientific and engineering issues are proposed in aspects such as the storage space and occurrence state of shale oil,the formation mechanisms of multi-scale flow spaces,the mobilization mechanisms of crude oil in pores and fractures,and the enhanced oil recovery(EOR)mechanisms during the late stage of elastic development.The research progress and mechanistic insights in recent years are reviewed with respect to experimental techniques,characteristics of pore-fracture structure and fluid occurrence,fracture evolution mechanisms,shale oil flow mechanisms and EOR techniques.Through improving the experimental methods,optimizing the testing conditions,and developing new technologies,we deeply understand the occurrence state,storage space and flow pattern of shale oil,and reveal the distribution pattern of“oil-bearing in all pore sizes and oil-rich in large pores”and the differences in fluid phase states under the confinement effect of nano-scale pores in the shales of the Jiyang Depression;depict the characteristics of“restricted vertical expansion and complex fracture networks”of induced fractures and the dynamic evolution of fracture networks during the fracturing-soaking-production process;establish a“easy flow-slow flow-stagnant flow”three-zone model and the elastic drive+imbibition drive synergistic energy replenishment mechanism;and carry out high-pressure injection to further enhance the mass transfer and diffusion capacity of CO_(2)within the shale pore-fracture system,and compete for the desorption of alkanes to improve the mobilization degree of shale oil.The research achievements provide crucial support for the formation of the theory of continental shale oil development and the construction of the technical system.The future research efforts will focus on mine-scale multi-field coupling physical simulation equipment,microscopic to macroscopic multi-scale experimental methods,pore/fracture fine characterization and post-fracturing core fracture description technologies,multi-media fluid-structure coupling numerical simulation algorithms,and low-cost EOR and low-quality shale oil in-situ upgrading technologies,in order to promote the large-scale and profitable development of shale oil in the Jiyang Depression.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of vario...The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of various compositions.All units contain a variety of mineral deposit types and their surrounding zones of hydrothermal alteration.Detailed geological and metallogenic research,after 30 years stagnation,has led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.The oldest magmatism comprises early Jurassic events,related to extensional tectonism,with volcanism and subvolcanic plutonism that ranged from rhyolitic,through dacitic and andesitic,and to basaltic.Additional extensional processes(in Bajocian times)were characterized by intrusion of a gabbro and diorite dike system into slightly older late Early Jurassicearly Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Intense hydrothermal activity related to this latest magmatism was responisble for important polymetallic mineralization including more than 100 historically recognized outcropping occurrences.A detailed study of 11of the more significant of these occurrences has indicated anomalous concentrations of base metals as well as gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant mineral occurrences were discovered,including two designated here as Gelia and Lechuri.展开更多
The Cloud Profiling Radar （CPR） onboard CloudSat is an active sensor specifically dedicated to cloud detection. Compared to passive remote sensors, CPR plays a unique role in investigating the occurrence of multi-la...The Cloud Profiling Radar （CPR） onboard CloudSat is an active sensor specifically dedicated to cloud detection. Compared to passive remote sensors, CPR plays a unique role in investigating the occurrence of multi-layer clouds and depicting the internal vertical structure of clouds. However, owing to contamination from ground clutter, CPR reflectivity signals are invalid in the lowest 1 km above the surface, leading to numerous missed detections of warm clouds. In this study, by using 1-yr CPR and MODIS （Moderate Resolution Imaging Spectroradiometer） synchronous data, those CPR-missed oceanic warm clouds that are identified as cloudy by MODIS are examined. It is demonstrated that CPR severely underestimates the occurrence of oceanic warm clouds, with a global-average miss rate of about 0.43. Over the tropical and subtropical oceans, the CPR-missed clouds tend to occur in regions with relatively low sea surface temperature. CPR misses almost all warm clouds with cloud tops lower than 1 km, and the miss rate reduces with increasing cloud top. As for clouds with cloud tops higher than 2 kin, the negative bias of CPR-captured warm cloud occurrence falls below 3%. The cloud top height of CPR-missed warm clouds ranges from 0.6 to 1.2 kin, and these clouds mostly have evidently small optical depths and droplet effective radii. The vertically integrated cloud liquid water content of CPR-missed warm clouds is smaller than 50 g m 2 It is also revealed that CPR misses some warm clouds that have small optical depths or small droplet sizes, besides those limited in the boundary layer below about 1 km due to ground clutter.展开更多
The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic e...The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41402126)
文摘ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on their formation mechanism.
基金the project IGCP-649 and was supported by RFBR (grant 17-05-00097)the Ural Branch of RAS (project 15-18-5-24)
文摘It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-crustal evolution of the ophiolites are undergoing significant changes with the formation of peculiar(on structure and composition)rocks,sometimes with unusual mineral paragenesis.The presence of such rocks in mélange tectonic zones greatly complicates to determine their origin.In the Ural folded belt(length more than 2,000 km)separating the East European Platform and the West Siberian sedimentary basin,ophiolites are widespread forming a chain of mafic-ultramafic massifs(Fig.1)located in the allochthonous position with mélange at the bottom(Puchkov,2013).With the Urals ophiolites are associated occurrences of eclogites,jadeites,ruby and other rocks of unclear nature,sometimes regarded as potentially diamondiferous.Such formations of unclear genesis include the associating with ophiolites metabasites of higher alkalinity composing the body in the mantle peridotites of the mélange Main Uralian Fault(MUF)zone(Shmelev,2005).By this time they are determined in different parts of the fault zone,but most completely are known in the Sub Polar Urals,where are distinguished under the name of Sertynya alkaline-ultramafic complex,which is located just 25 km east of Hartes kimberlitic complex(Fig.1).Formally,its affiliation to diamond-bearing associations is confirmed by finding of grains and fragments of natural diamond in the weathering crust.A detailed study of the rock complexes shows that in reality they have a polygenic nature,combine theelements of proper magmatic and fluidizate-explosive formations,the appearance of which was interfaced with the processes at the slab-mantle wedge boundary in subduction zones.Polygenic nature of the rocks is reflected in the existence of three interrelated structural-geological units:(1)bodies and dikes of uniformmetadiabasesanddensefine-grainedmetadolerites(lamprophyres),(2)fluidal-brecciated dolerites('tuff breccias')and(3)structural weathering crust with angular or rounded fragments(blocks)of metadolerites and serpentinites.The rocks have experienced rodingitization and permeated with net of veins a vesuvianite composition.The host peridotite matrix(harzburgites and dunites)has undergone serpentinizationandchloritization.Structural relationships give grounds for distinguishing in the history of the complex formation the magmatic proper(dolerite dyke and lamprophyre intrusion)and infiltration fluidizate-explosive(metasomatic transformation of dolerite)stages.Peculiarities of petrography and mineralogy of rock complexes does not allow to compare them with lamproites and kimberlites.Metadiabases demonstrate relics of ophitic structure,as primary paragenesis is completely replaced by aggregate of chlorite,zoisite and leucoxene.Dolerites(lamprophyres)have a uniform fine-grained or porphyry structure with phenocrysts of clinopyroxene,brown amphibole and leucoxene(sphene),which are immersed in a fine-scaly aggregate of light green mica.In the rocks amphibole,garnet and vesuvian are present.Clinopyroxene corresponds to augite with moderate content of titanium and alumina(up to 3.5wt.%),showing a normal magmatic zonation in composition.Mica previously wrongly called as phlogopite,actually has an extremely ferrous composition and corresponds to biotite(annite).Amphibole is presented by magmatic titaniferous tschermakite hornblende and metamorphic(bluish)variety of sodium-calcium composition(taramite).Garnet is presented by exceptionally grossular of rodingite type.Mineralogy of weathering crust reveals similar features,but in the samples it is marked the presence of muscovite,orthoclase and weakly ferrous diopside.An important feature of the weathering crust is the presence of shear surfaces on minerals,resulting in fracturing due to internal stress,confirming the explosive nature of protolith.The bulk chemical composition of rocks is characterized by significant variations in the content of silica(30-46 wt.%)and alkalis(0-6.5 wt.%).These metabasites have consistently a low magnesia number and high titanium oxide content(1.5-3.0 wt.%).Side by side with these are been established the uniform slope REE distribution trends similar to the trend of oceanic basalts N-MORB type(Fig.2).The level of trace element compositions does not depend on variations in the alkalinity of the rocks,but clearly correlates with the titanium content.Unlike them the Hartes kimberlites demonstrate the distribution with deficit of HREE,andthe level of the elements content is correlated with the alkalinity of rocks(Mahotkin et al.,1998).Another important geochemical feature of the Sertynya complex rocks is a regular behavior of the mobile LILE elements(Cs,Rb,Ba,K).In the varieties of rocks with mica enriched by alkalis,it is recorded extremely high level of LILE,exceeding the level of contents in N-MORB basalts at 10-10000 times!In the metabasites varieties with low level of alkalinity,LILE content is sharply(except Cs)reduced to minimum values(Fig.2).The observed pattern of the element distribution is undoubtedly the result of postmagmatic fluid-metasomatic alteration of the original rocks.Tectonic position and the primary composition characteristics of the metadolerites give reason to consider them as fragments of the ophiolite sheeted dike complex(Shmelev,2005).The famous dike complexes in the ophiolite massifs of the MUF zone(east of mélange)belong to suprasubduction formations of Paleozoic age.However the obtained mainly ancient U-Pb zircon dating(up to Archean inclusive)for metadolerites of the Sertynya complex,make it possible to assume its Vendian-Early Cambrian(530-617 Ma)age.It permits to compare the Sertynya metabasites with the Vendian metaophiolites of the MUF zone in the Middle Urals(Petrov et al.,2010).It is noteworthy that similar age datings(520-550 Ma)are also established for kimberlites of the Hartes complex located to the west of ophiolites.Therefore,thepresenceofthe Vendian-Cambrian ophiolite of MOR-type in the MUF mélange zone,'changing'to the east of Ordovician ophiolites SSZ-type,seems quite possible.The obtained data allow to suggest an original interpretation of nature of the Urals fluidizate-explosive formations considering the process specifics in the subduction zones(Bebout and Barton,2002).Accordingto this model,the pre-Ordovician(?)oceanic crust has undergone transformations and deformations on the slab-mantle wedge boundary during the subduction.As a result of slab dehydration it occurred a flow of aqueous fluids,which were enriched with the extracted from sedimentary rocks the LILE elements and percolated through the mantle substrate with dolerite dyke complex.Interaction with them led to the formation of chlorite-zoisite and/or mica(biotite-bearing)fluidizates and in the presence of a gas phase-fluidizate-explosive breccias with subsequent development of weathering crust.In the surrounding peridotites an explosive process is marked by the formation of pseudokimberlite breccias.Fluidized-explosive occurrences in mantle peridotites of mélange zones should be considered as indicators of the subduction slab-mantle interaction at relatively shallow levels involving enriched LILE fluids(without melts participation),rising as the front from the subduction zone.In this interpretation,there is no need toappealtothealkaline-ultramaficor lamproit-kimberlite hypothesis of the genesis of these formations,however,the question of their potential diamondiferous remains to be open.The proposed interpretation of the fluidizate-explosive occurrences makes it possible to comprehendthat in reality the mélange is a complex formation with signs of not onlycollisional(as usually is considered),but also of earlier subduction events.
基金the Rustaveli National Science Foundation of Georgia for funding the project(#GNSF/ST09-1071-5-150).
文摘Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bodies of various compositions.All units contain a variety of ore mineral deposit types and their surrounding zones of hydrothermal alteration.Continued geological and metallogenic researches in the past 30 years have led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.Oldest magmatism comprises Early Jurassic events,related to extensional tectonism,which ranged from rhyolitic,through dacitic and andesitic,and to basaltic magma.Additional extensional processes(in Bajocian)were characterized by intrusion of a gabbro and diorite dike system into recently deposited late Early Jurassic-early Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Related intense hydrothermal activity was responsible for important polymetallic mineralization,with more than 100 recognized outcropping ore occurrences.A detailed study of 11 of these ore occurrences has indicated anomalous concentrations of gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant ore mineral occurrences were discovered.
基金the National NaturalScience Foundation of China(No.40072054)the Coal Science Foundation of China(No.97Geo-10205).
文摘The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer. And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A, HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperature hydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.
基金supported by the State Key Basic Research Program 973(No.2006CB202308)
文摘The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in oil or water. Based on the production test data of exploratory wells in the Tazhong uplift of the Tarim basin, this paper discusses in detail the differences in occurrence and distribution featrues between the surface and underground natural gases; presents a restoration of the surface gas occurrence to actual underground geologic conditions according to the dissolubility of natural gas under different temperature, pressure and medium conditions; and classifies the natural gas into three states, i.e. the oversaturated, saturated and undersaturated, according to its relative content underground. Through a comparative analysis of the differences in surface and underground occurrences of natural gas, it discusses the hydrocarbon reservoir formation mechanism and distribution rules, thereby providing guidances as new methods and technologies for the prediction of potential natural gas reservoir distribution in the study area.
基金supported by the National Basic Research Program of China (973 Program) (2012CBA01200)Northern Rare Earth Science and Technology Project (BFXT-2015D-0002) and (2016H1928)
文摘The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analysis,field emission scanning electron microscopy,energy dispersive spectrometer,and automatic mineral analysis software.Results identified that 91.69%of ThO2 in the combined samples was mainly distributed in rare earth minerals(bastnaesite,huanghoite,monazite;56.43%abundance in the samples),iron minerals(magnetite,hematite,pyrite;20.97%),niobium minerals(aeschynite;14.29%),and gangue minerals(aegirine,riebeckite,mica,dolomite,apatite,fluorite;4.22%).An unidentified portion(4.09%)of ThO2 may occur in other niobium minerals(niobite,ilmenorutile,pyrochlore).Only a few independent minerals of thorium occur in the iron ore samples.Thorium mainly occurs in rare earth minerals in the form of isomorphic substitution.Analyses of the geochemical characteristics of the major elements indicate that thorium mineralization in the Main Ore Body was related to alkali metasomatism,which provided source material and favorable porosity for hydrothermal mineralization.Trace elements such as Sc,Nb,Zr,and Ta have higher correlation coefficients with thorium,which resulted from being related to the relevant minerals formed during thorium mineralization.In addition,correlation analysis of ThO2 and TFe,and REO and TFe in the six types of iron ore samples showed that ThO2 did not always account for the highest distribution rate in rare earth minerals,and the main occurrence minerals of ThO2 were closely related to iron ore types.
文摘A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent minerals in nature and occasionally as ion adsorption, isomorphous or amorphous silver minerals. Nearly 190 silver minerals have been discovered in China. Their shapes, constituents, textures, grain sizes, embedded types, distribution patterns, mineral assemblages and metallogenic series suggest that these characteristics are closely related to geneses of deposits and dependent of ore-forming conditions. Pb, Zn and Cu sulphides are the main carrier minerals of silver. The partition of silver in ore is constrained by the mineralization intensity, grain size and embedded form of silver minerals and mineral assemblages.
文摘The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E) and its adjacent area up to 1991 were analyzed systematically.These earthquakes are called as strong earthquakes and those of the east before and after 1600,and those of the west before and after 1900, are called respectively as former ones and latter ones.Most of these events were divided into 45 sets of which the each relatively concentrated in both time and space and took the form of group.In the grouping form,the probability of occurrence of a strong earthquake higher than the average appeared simultaneously in time and space.The grouping occurrences of the strong earthquakes of Chinese mainland has been determined as a fundamental feature of the seismicity.
文摘This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four kinds of diseases as well as the coping strategies of people in the area.We collected the rainfall and temperature data of Lokoja City during 2000-2020 from the National Aeronautics and Space Administration(NASA),and the medical records data of the four kinds of diseases from the Kogi State Ministry of Health.We also conducted a semi-structured questionnaire of 250 residents,who have experienced one of these diseases,to investigate their coping strategies with these diseases.The Pearson correlation and multiple regression analysis were used to research the relationship between the climate parameters and cases of diseases.The result showed annual variations in climatic parameters with R^(2)values of 0.0557,0.0009,and 0.4915 for rainfall,maximum temperature,and minimum temperature,respectively.A positive and significant relationship were observed between maximum temperature and malaria(r=0.80),rainfall and malaria(r=0.54),minimum temperature and meningitis(r=0.64),as well as rainfall and cholera(r=0.66)at P<0.05 level.For the regression analysis R^(2)=0.71,0.50,and 0.52 for malaria,cholera,and meningitis,respectively at P<0.05 level.During 2000-2020,cases of malaria were highest in Ward A with 15,422,while 715 cases of pneumonia were highest in Kupa North Ward.In Ward A,3787 cases of cholera were recorded to be the highest,while cases of meningitis were highest in Kupa North Ward with 2383 cases.Investigation revealed that malaria is more common in the wet season,while cholera and meningitis cases were highest in the dry season.The study revealed that the most practiced coping strategy is the use of medications by about 90%of the respondents.More studies are recommended in the study area to establish a causal link between climate change and disease occurrence,and intervention from government in form of prevention and control programmes should be vigorously implemented.
文摘This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.
基金supported by the China Postdoctoral Science Foundation (No.2021M703001)Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan) (No.G1323521101)+3 种基金open fund of State Key Laboratory of Nuclear Resources and Environment (East China University of Technology) (No.2022NRE02)open fund of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences (Wuhan)),Ministry of Education (No.TPR2019-08)Fund of Outstanding Talents in Discipline of China University of Geosciences (Wuhan) (No.102162301192664)support from SINO Shaanxi Industry Group in this study。
文摘Carbonaceous debris(CD) is widely disseminated within sandstones in the Shuanglong uranium deposit,southern Ordos Basin,and is the dominant enrichment agent for uranium precipitation.The occurrence and chemical composition of uranium minerals within CD were investigated by using scanning electron microscope and electron microprobe analyses.The results show that uranium minerals mostly occur in cell pores in the forms of fructus aurantia and concentric band structure.Pitchblende and coffinite are the main uranium minerals,and the former is dominant.According to the crystal morphology and composition of trace elements of uranium minerals,uranium precipitation on the pores is grouped into two periods,orderly Ⅰ,Ⅱ.Moreover,the Ⅰ period is further divided into two sub-period,orderly Ⅰ_(1),Ⅰ_(2).Moreover,askew sphere uranium minerals could indicate fluid migration.Under certain geological environment condition,uranium is unevenly adsorbed on the surface of the pore by the Van der Waals(i.e.,Ⅰ_(1) period),and then is precipitated towards to the center of the pore until the whole pore is filled up with uranium minerals by complicated process such as microorganism activities(i.e.,Ⅰ_(2),Ⅱ period).It will provide some guidance for studying the metallogenic environment and genesis of sandstone-type uranium deposit.
基金supported by the Key R&D Projects in Hainan Province(No.ZDYF2024SHFZ085)Hainan Provincial Joint Project of Sanya Yazhou Bay Science and the Technology City(No.2021CXLH0009)the National Natural Science Foundation of China(No.42376234).
文摘This paper takes the water body of Daliao River-Liaodong Bay as the research object,divides it into three regions:river,estuary,and offshore,and analyzes the changes of antibiotics and antibiotic resistance genes(ARGs)from inland rivers to the sea and the environmental impact factors from this perspective.The results showed that in general,the pollution of antibiotics and ARGs in Daliao River-Liaodong Bay belonged to the medium-low level,and levels of antibiotics and ARGs were nd–106.23 ng/L and nd–1.95×10^(8)copies/L,respectively.The concentrations and types of antibiotics and ARGs decreased from inland to sea regions.Analysis of the distributional characteristics of antibiotics and ARGs from a regionalized perspective revealed significant differences among the three regions in sulfonamide antibiotics,tetracycline antibiotics,and dominant ARGs.Sulfonamide antibiotic levels were significantly higher in the estuarine zone than in the riverine and offshore zones;tetracycline antibiotic levels were significantly higher in the riverine and estuarine zones than in the offshore zone.Aminoglycosides were dominant in the riverine and estuarine zones,and macrolides were dominant in the offshore zone.We characterized the effects of environmental factors on the assignment of antibiotics and ARGs and found that overall temperature contributed the most to variation in antibiotics and ARGs;the contribution of dissolved oxygen was the lowest.The estuarine zone was most affected by these factors,followed by the offshore zone and finally the riverine zone.
基金Supported by Innovation Project of Hebei Academy of Agricultural and Forestry Sciences(2022KJCXZX-CGS-7)Hebei Agriculture Research System(HBCT2024170406).
文摘This paper presents an overview of the pathogens, symptoms of damage, patterns of occurrence, and chemical control methods associated with four major pear tree diseases: pear scab, pear ring rot, pear anthracnose, and pear speckle. The objective is to provide valuable references for the scientific and precise prevention and management of diseases in pear orchards, thereby contributing to the production of high-quality and high-yield pear fruits.
基金funded by the National University of Río Negro Research Project (40-C-658)
文摘Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.
基金financially supported by the National Natural Science Foundation of China(Nos.42272137,42202160)AAPG Foundation Grants-in-Aid and the Strategic Cooperation Technology Projecti of CNPC and CUPB(No.ZLZX2020-01-05)。
文摘The pore structure of shale oil reservoir significantly affects the occurrence and mobility of hydrocarbons.The potential of a new type of alkaline lake shale oil has been demonstrated,but there are few reports on the pore system of alkaline lake shale,which restricts the efficient exploration and development of shale oil.This study investigates the Fengcheng Formation shale in the Mahu sag of the Junggar Basin,employing methods such as low-temperature nitrogecn adsorption(LTNA),mercury intrusion capillary pressure(MICP),and nuclear magnetic resonance(NMR)to quantitatively characterize the multi-scale pore structure and fractal characteristics of shale,while evaluating the applicability of these methods.Based on a comprehensive analysis of material composition,different pore types,and fractal dimensions,the controlling factors for the development of different pore types and their seepage capacity are discussed.The results indicate that inorganic mineral pores are the main development in alkaline lake shale,with the pore morphology being characterized by slit-like and ink-bottle shapes.The multi-scale pore size distribution(PSD)shows that Ⅱ-micropores(10-100 nm)and mesopores(100–1000 nm)are the main contributors to the pore system.The development of Ⅱ-micropores is associated with feldspar and calcareous minerals,the development of Ⅰ-micropores(<10 nm)and mesopores is related to quartz content,while large pores are mainly found in interlayer fissures of clay minerals.The development of Ⅰ-micropores increases the roughness of pore surface and enhances the adsorption capacity of the pores,while the development of Ⅱ-micropores associated with calcareous minerals hinders pore seepage capacity.Mesopores and macropores(>1000 nm)exhibit good flowability.The high content of siliceous minerals plays a positive role in the pore system of alkaline lake shale.The shale with higher fractal dimension Dmin exhibits greater adsorption capacity,which hinders the accumulation of free-state shale oil.Different types of pore space play different roles in the occurrence of shale oil,with free-state shale oil primarily occurring in micro-fractures and inorganic mineral pores,and the pore size is exceeding 10 nm.
基金Supported by the China National Science and Technology Major Project(2024ZD1405103)SINOPEC Science and Technology Major Project(P25184)。
文摘Centering on the critical bottlenecks in the development of shale oil in the Jiyang Depression of Shengli Oilfield,key scientific and engineering issues are proposed in aspects such as the storage space and occurrence state of shale oil,the formation mechanisms of multi-scale flow spaces,the mobilization mechanisms of crude oil in pores and fractures,and the enhanced oil recovery(EOR)mechanisms during the late stage of elastic development.The research progress and mechanistic insights in recent years are reviewed with respect to experimental techniques,characteristics of pore-fracture structure and fluid occurrence,fracture evolution mechanisms,shale oil flow mechanisms and EOR techniques.Through improving the experimental methods,optimizing the testing conditions,and developing new technologies,we deeply understand the occurrence state,storage space and flow pattern of shale oil,and reveal the distribution pattern of“oil-bearing in all pore sizes and oil-rich in large pores”and the differences in fluid phase states under the confinement effect of nano-scale pores in the shales of the Jiyang Depression;depict the characteristics of“restricted vertical expansion and complex fracture networks”of induced fractures and the dynamic evolution of fracture networks during the fracturing-soaking-production process;establish a“easy flow-slow flow-stagnant flow”three-zone model and the elastic drive+imbibition drive synergistic energy replenishment mechanism;and carry out high-pressure injection to further enhance the mass transfer and diffusion capacity of CO_(2)within the shale pore-fracture system,and compete for the desorption of alkanes to improve the mobilization degree of shale oil.The research achievements provide crucial support for the formation of the theory of continental shale oil development and the construction of the technical system.The future research efforts will focus on mine-scale multi-field coupling physical simulation equipment,microscopic to macroscopic multi-scale experimental methods,pore/fracture fine characterization and post-fracturing core fracture description technologies,multi-media fluid-structure coupling numerical simulation algorithms,and low-cost EOR and low-quality shale oil in-situ upgrading technologies,in order to promote the large-scale and profitable development of shale oil in the Jiyang Depression.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
基金Rustaveli National Science Foundation of Georgia for funding the project(#GNSF/ST09-1071-5-150)through which the research work was conducted in the eastern Greater Caucasus.
文摘The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of various compositions.All units contain a variety of mineral deposit types and their surrounding zones of hydrothermal alteration.Detailed geological and metallogenic research,after 30 years stagnation,has led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.The oldest magmatism comprises early Jurassic events,related to extensional tectonism,with volcanism and subvolcanic plutonism that ranged from rhyolitic,through dacitic and andesitic,and to basaltic.Additional extensional processes(in Bajocian times)were characterized by intrusion of a gabbro and diorite dike system into slightly older late Early Jurassicearly Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Intense hydrothermal activity related to this latest magmatism was responisble for important polymetallic mineralization including more than 100 historically recognized outcropping occurrences.A detailed study of 11of the more significant of these occurrences has indicated anomalous concentrations of base metals as well as gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant mineral occurrences were discovered,including two designated here as Gelia and Lechuri.
基金Supported by the National Natural Science Foundation of China(41175032)
文摘The Cloud Profiling Radar （CPR） onboard CloudSat is an active sensor specifically dedicated to cloud detection. Compared to passive remote sensors, CPR plays a unique role in investigating the occurrence of multi-layer clouds and depicting the internal vertical structure of clouds. However, owing to contamination from ground clutter, CPR reflectivity signals are invalid in the lowest 1 km above the surface, leading to numerous missed detections of warm clouds. In this study, by using 1-yr CPR and MODIS （Moderate Resolution Imaging Spectroradiometer） synchronous data, those CPR-missed oceanic warm clouds that are identified as cloudy by MODIS are examined. It is demonstrated that CPR severely underestimates the occurrence of oceanic warm clouds, with a global-average miss rate of about 0.43. Over the tropical and subtropical oceans, the CPR-missed clouds tend to occur in regions with relatively low sea surface temperature. CPR misses almost all warm clouds with cloud tops lower than 1 km, and the miss rate reduces with increasing cloud top. As for clouds with cloud tops higher than 2 kin, the negative bias of CPR-captured warm cloud occurrence falls below 3%. The cloud top height of CPR-missed warm clouds ranges from 0.6 to 1.2 kin, and these clouds mostly have evidently small optical depths and droplet effective radii. The vertically integrated cloud liquid water content of CPR-missed warm clouds is smaller than 50 g m 2 It is also revealed that CPR misses some warm clouds that have small optical depths or small droplet sizes, besides those limited in the boundary layer below about 1 km due to ground clutter.
基金supported by the National Natural Science Foundation of China(52304021,52104022,52204031)the Natural Science Foundation of Sichuan Province(2022NSFSC0205,2024NSFSC0201,2023NSFSC0947)the National Science and Technology Major Projects of China(2017ZX05049006-010).
文摘The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.
