The Binchuan area of Yunnan is located in the western part of the Emeishan large igneous province in the western margin of the Yangtze Block. In the present study, the Wuguiqing profile in thickness of about 1440 m is...The Binchuan area of Yunnan is located in the western part of the Emeishan large igneous province in the western margin of the Yangtze Block. In the present study, the Wuguiqing profile in thickness of about 1440 m is mainly composed of high-Ti basalts, with minor picrites in the lower part and andesites, trachytes, and rhyolites in the upper part. The picrites have relatively higher platinum- group element （PGE） contents （PGE=16.3-28.2 ppb）, with high Cu/Zr and Pd/Zr ratios, and low S contents （5.03-16.9 ppm）, indicating the parental magma is S-unsaturated and generated by high degree of partial melting of the Emeishan large igneous province （ELIP） mantle source. The slightly high Cu/Pd ratios （11 000-24 000） relative to that of the primitive mantle suggest that 0.007% sulfides have been retained in the mantle source. The PGE contents of the high-Ti basalts exhibit a wider range （~PGE=0.517-30.8 ppb）. The samples in the middle and upper parts are depleted in PGE and have ~Nd （260 Ma） ratios ranging from -2.8 to -2.2, suggesting that crustal contamination of the parental magma during ascent triggered sulfur saturation and segregation of about 0.446%-0.554% sulfides, and the sulfide segregation process may also provide the ore-forming material for the magmatic Cu-Ni-PGE sulfide deposits close to the studied basalts. The samples in this area show Pt- Pd type primitive mantle-normalized PGE patterns, and the Pd/Ir ratios are higher than that of the primitive mantle （Pd/Ir=l）, indicating that the obvious differentiation between Ir-group platinum- group elements （IPGE） and Pd-group platinum-group elements （PPGE） are mainly controlled by olivine or chromites fractionation during magma evolution. The Pd/Pt ratios of most samples are higher than the average ratio of mantle （Pd/Pt=0.55）, showing that the differentiation happened between Pt and Pd. The differentiation in picrites may be relevant to Pt hosted in discrete refractory Pt-alloy phase in the mantle; whereas the differentiation in the high-Ti basalts is probably associated with the fractionation of Fe-Pt alloys, coprecipitating with Ir-Ru-Os alloys. Some high-Ti basalt samples exhibit negative Ru anomalies, possibly due to removal of laurite collected by the early crystallized chromites.展开更多
The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerge...The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.展开更多
In December 2020, Chang’E-5(CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain,...In December 2020, Chang’E-5(CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain, a great distance from those of Apollo and Luna missions. These young mare basalts bear critical scientific significance as they could shed light on the nature of the lunar interior(composition and structure) as well as the recent volcanism on the Moon. In this article, we investigated a CE-5 basalt sample(CE5 C0000 YJYX065) using a combination of state-of-art techniques, including high resolution X-ray tomographic microscopy(HR-XTM), energy dispersive X-ray spectroscopy(EDS)-based scanning electron microscope(SEM), and electron probe microanalysis(EPMA) to reveal its 3 D petrology and minerology.Our results show that this sample has a fine-to medium-grained subophitic texture, with sparse olivine phenocrysts setting in the groundmass of pyroxene, plagioclase, ilmenite and trace amounts of other phases. It has an extremely high ilmenite modal abundance(17.8 vol%) and contains a significant amount(0.5 vol%) of Ca-phosphate grains. The mineral chemistry is in excellent agreement with that of Apollo and Luna high-Ti basalts. The major phase pyroxenes also display strong chemical zoning with compositions following the trends observed in Apollo high-Ti basalts. Based on current data, we came to the conclusion that CE5 C0000 YJYX065 is a high-Ti mare basalt with a rare earth element(REE) enriched signature. This provides a rigid ground-truth for the geological context at the CE-5 landing site and clarifies the ambiguity inferred from remote sensing surveys.展开更多
Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the ...Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.展开更多
This study investigates the compressive and tensile properties of basalt fiber-reinforced concrete (BFRC) after ultra-low-temperature freeze-thaw cycles. Scanning electron microscope (SEM) analysis was conducted to ex...This study investigates the compressive and tensile properties of basalt fiber-reinforced concrete (BFRC) after ultra-low-temperature freeze-thaw cycles. Scanning electron microscope (SEM) analysis was conducted to examine the deterioration mechanisms caused by freeze-thaw cycles and sulfate erosion. The results show that compressive and tensile strengths increase with basalt fiber dosage. The optimal dosage is 0.2%. With longer exposure to sulfate erosion, both strengths decline significantly. Basalt fibers effectively bridge cracks, control expansion, enhance compactness, and improve concrete performance. Ultra-low-temperature freeze-thaw cycles and sulfate erosion cause rapid crack growth. Sulfate erosion produces crystallization products and expansive substances. These fill cracks, create pressure, and damage the internal structure. Freezing and expansion forces further enlarge voids and cracks. This provides space for expansive substances, worsening concrete deterioration and reducing its performance.展开更多
Sizing treatment is a suitable technique to modify the fiber-matrix interfaces without damage of inherent performance of fibers.In this work,sizing agents based on Janus particles(JPs)were utilized to enhance the inte...Sizing treatment is a suitable technique to modify the fiber-matrix interfaces without damage of inherent performance of fibers.In this work,sizing agents based on Janus particles(JPs)were utilized to enhance the interface of basalt fiber(BF)/poly(vinyl chloride)(PVC)composites.polystyrene/poly(butyl acrylate)(PS/PBA)@silica JPs were synthesized by seed emulsion polymerization and three different sizing agents were prepared for BF sizing treatment.JPs with organic soft sphere and inorganic hard hemisphere enhanced the interfaces through their amphiphilicity,chemical bonding and mechanical interlock.The mechanical properties of composite with JPs sizing treated BFs performed better when there was one JPs layer modified on the interface.According to the intermitting bonding and gradient modulus theory,JPs patterned interfaces are ideal transition layers between high modulus BF and low modulus PVC.展开更多
The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for...The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for the first time a suite of columnar basalts from the Mesoarchean Coorg Block in the Southern Granulite Terrain(SGT)of India and characterize these rocks through field,petrological,geo-chemical,and isotope geochronological studies.The basalts show porphyritic texture with phenocrysts of pyroxene and plagioclase embedded in fine groundmass.Geochemical data reveal tholeiitic flood basalt affinity with affinities of plume-related magmatism.The zircon U-Pb data of the rocks yield a weighted mean age of 137 Ma,thus corresponding to the Valanginian Age of the Early Cretaceous Period.We suggest the possible geochemical affinity of the studied rocks Kerguelen plume basalts which provide new insights into magmatism associated with the final stages of East Gondwana rifting.展开更多
Mitigating climate change demands innovative solutions,and carbon sequestration technologies are at the forefront.Among these,basalt,a mafic volcanic rock packed with calcium,magnesium,and iron,emerges as a powerful c...Mitigating climate change demands innovative solutions,and carbon sequestration technologies are at the forefront.Among these,basalt,a mafic volcanic rock packed with calcium,magnesium,and iron,emerges as a powerful candidate for carbon dioxide(CO_(2))sequestration through mineral carbonation.This method transforms CO_(2)into stable carbonate minerals,ensuring a permanent and environmentally safe storage solution.While extensive research has explored into basalt’s potential under high hydration conditions,the untapped promise of low water content scenarios remains largely unexplored.Our ground-breaking study investigates the mineral carbonation of basalt powder under low water condi-tions using supercritical CO_(2)(sc-CO_(2)).Conducted at 50℃ and 15 MPa with a controlled moisture content of 30%,our experiment spans various time points(0,7,14,21,and 28 days).Utilising advanced X-ray diffraction(XRD)and scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM-EDS),we unveil the mineralogical and morphological transformations.The results are striking:even under low water conditions,basalt efficiently forms valuable carbonate minerals such as calcite,siderite,magnesite,and ankerite.The carbonation efficiency evolves over time,reflecting the dynamic transfor-mation of the basalt matrix.These findings offer pivotal insights into optimising CO_(2)sequestration in basalt under low hydration,marking a significant leap toward sustainable carbon capture and storage.展开更多
The Longshan orogenic belt is located in the southwestern margin of Ordos Basin at the junction zone between the Western Qinling and Northern Qilian orogenic belt.Voluminous Early Paleozoic magmatism in this area is o...The Longshan orogenic belt is located in the southwestern margin of Ordos Basin at the junction zone between the Western Qinling and Northern Qilian orogenic belt.Voluminous Early Paleozoic magmatism in this area is of key significance for determining the Early Paleozoic tectonic evolution and deep crust-mantle structure.Previous studies mainly focused on the Paleozoic granites;the coeval mafic rocks in this area are still poorly understood.A set of Late Silurian intraplate tholeiitic basalts has been discovered in Longshan area,providing key evidence for the mantle source and deep geodynamic background in this area.The Late Silurian Angou basalt has similar geochemical features as intraplate tholeiitic basalt,with high Na_(2)O/K_(2)O ratios(5.22-8.25),enriched in large ion lithophile elements and LREE.In combination with their relatively evolved Sr-Nd isotopic composition[^(87)Sr/^(86)Sr(i)=0.7128-0.7140;ε_(Nd)(t)=-5.55 to-3.40],it is suggested that it originated from decompression melting of metasomatized enriched mantle in extensional setting.These results indicate that the mantle source in the junction zone of the West Qinling-North Qilian orogenic belt evolved from depleted to enriched with the continuation of Proto-Tethys subduction from the Cambrian to the Silurian.These results are of great significance to understanding the genesis of contemporaneous granite and the crust-mantle interaction in the junction zone between the Western Qinling and Northern Qilian orogenic belt.展开更多
As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scienti...As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scientific drilling project on the Xisha Islands in the northwestern SCS.It penetrates the thick reef limestone and reaches basaltic pyroclastic rocks.This study presents the whole-rock and olivine compositions of the basaltic volcaniclastic rocks from Well CK-2.These rocks exhibited ocean island basalt signatures characterized by the enrichment of light rare earth elements and high-field-strength elements.Compared with partial melting products derived from mantle peridotite,whole-rock compositions showed elevated Fe/Mn and Zn/Fe mass ratios.Additionally,olivines were characterized by a lower Ca content,higher Ni content,elevated Fe/Mn mass ratios,and moderate Mn/Zn mass ratios compared to those crystallized from peridotitic melts.The compositions of both the whole-rock and olivine phenocrysts indicate the presence of pyroxenite in the mantle source,which likely formed through the reaction of recycled oceanic crust with the surrounding mantle peridotite.Using the olivine-liquid Mg-Fe exchange thermometer,this study derived mantle potential temperatures(T_(p))ranging from 1502℃to 1756℃,which is consistent with those of plume-related ocean island basalts.Furthermore,the basaltic volcaniclastic rocks exhibit low H_(2)O contents(0.01%–1.47%),which were significantly lower than those found in the primary magmas of Large Igneous Provinces.These results suggest that the basaltic volcaniclastic rocks on the Xisha Islands originated from a volatile-poor mantle plume source.展开更多
Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot presse...Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.展开更多
The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+...The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+SiO_(2))mass ratio while the total iron content is reduced.Thermodynamic analysis indicates that the increase in(CaO+SiO_(2))mass ratio from 15.0 to 22.5 wt.%contributes to the formation of liquid phase,especially silico-ferrite of calcium and aluminum(SFCA).In addition,the formation of perovskite is inhibited and liquid phase fluidity is improved.The porosity of sinter matrix is reduced by 34.5%and SFCA amount is increased by 47.2%when(CaO+SiO_(2))mass ratio is increased from 15.0 to 18.0 wt.%.With the further increase in(CaO+SiO_(2))mass ratio,the structure of sinter matrix is too dense and the improved extent of SFCA amount is increasingly low.The appropriate(CaO+SiO_(2))mass ratio should be 18.0 wt.%overall.Under this condition,sinter matrix strength is greatly improved by over 13.5%compared with the base case and the total iron content can be maintained at about 49 wt.%.展开更多
Foamed concrete has been used to address the issue of differential settlement in high-speed railway subgrades in China.However,to enhance crack resistance,reinforcement is still necessary,and further research is requi...Foamed concrete has been used to address the issue of differential settlement in high-speed railway subgrades in China.However,to enhance crack resistance,reinforcement is still necessary,and further research is required to better understand the performance of foamed concrete in subgrade applications.To this end,a series of tests—including uniaxial compres-sive and dynamic triaxial tests—were conducted to comprehensively examine the effects of basalt fiber reinforcement on the mechanical properties of foamed concrete with densities of 700 and 1000 kg/m3.Additionally,a full-scale model of the foamed concrete subgrade was established,and simulated loading was applied.The diffusion patterns of dynamic stress and dynamic acceleration within the subgrade were explored,leading to the development of experimental formulas to calculate the attenuation coefficients of these two parameters along the depth and width of the subgrade.Furthermore,the dynamic displacement and cumulative settlement were analyzed to evaluate the stability of the subgrade.These findings provide valuable insights for the design and construction of foamed concrete subgrades in high-speed rail systems.The outcomes are currently under consideration for inclusion in the code of practice for high-speed rail restoration.展开更多
Although supercritical carbon dioxide(SC-CO_(2))fracturing shows tremendous potential for maximizing injection efficiency and enhancing storage volumes,few investigations have been reported on the SC-CO_(2) fracturing...Although supercritical carbon dioxide(SC-CO_(2))fracturing shows tremendous potential for maximizing injection efficiency and enhancing storage volumes,few investigations have been reported on the SC-CO_(2) fracturing characteristics of tight basalts and the reactions between fractured basalt and SC-CO_(2).In this study,hydraulic fracturing experiments were conducted on cylindrical basalt specimens using water and SC-CO_(2) as fracturing fluids.Geometric parameters were proposed to characterize the fracture morphologies based on the three-dimensional(3D)reconstructions of fracture networks.The rock slices with induced fractures after SC-CO_(2) fracturing were then processed for fluid(deionized water/SC-CO_(2))-basalt reaction tests.The experimental results demonstrate that SC-CO_(2) fracturing can induce complex and tortuous fractures with spatially dispersed morphologies.Other fracturing behaviors accompanying the acoustic emission(AE)signals and pump pressure changes show that the AE activity responds almost simultaneously to variation in the pump pressure.The fractured basalt blocks exposed to both SC-CO_(2) and water exhibit rough and uneven surfaces,along with decreased intensities in the element peaks,indicating that solubility trapping predominantly occurs during the early injection stage.The above findings provide a laboratory research basis for understanding the fracturing and sequestration issues related to effective CO_(2) utilization.展开更多
The size of basalt fragments in Chang’E-5(CE-5)regolith are small(<6 mm^(2)),resulting in large variation on the estimated bulk composition of CE-5 basalt.For example,the estimated TiO_(2) content of CE-5 basalt r...The size of basalt fragments in Chang’E-5(CE-5)regolith are small(<6 mm^(2)),resulting in large variation on the estimated bulk composition of CE-5 basalt.For example,the estimated TiO_(2) content of CE-5 basalt ranges from 3.7 wt% to 12.7 wt% and the Mg#(molar percentage of Mg/[Mg+Fe])also shows a wide range(26.2-42.4).Preliminary experimental studies have shown that these geochemical characteristics of CE-5 basalt are critical for investigating the crystallization sequence and formation mechanism of its parent magma.This study presents new experimental data on the distribution coefficient of titanium between pyroxene and lunar basaltic magma(D_(Ti)^(Px/melt)).Combining with available literature data,we confirm that D_(Ti)Px/melt is affected by crystallization conditions such as pressure and temperature,but it is mainly controlled by the CaO content of pyroxene.Comparing with previous experimental results under similar conditions,we parameterized the effect as D_(Ti)^(Px/Melt)=D_(Ti)^(Px/Melt)=-0.0005X_(Cao)^(2)+0.0218X_(CaO)+0.0425(R^(2)=0.82),where X_(CaO) is the CaO content in pyroxene in weight percentage.The new experimental results suggest that pyroxene with high TiO_(2) content(>2.5 wt%)in CE-5 basalt is not a product of equilibrium crystallization,and the CaO content in pyroxene is also affected by cooling rate of its parent magma.The TiO_(2) content in the CE-5 parent magma is estimated to be about 5 wt% based on the Mg# of pyroxene and its calculated CaO content,which is consistent with those estimated from olivine grains.展开更多
Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemi...Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemical characteristics of continental intraplate basalts are controversial.In this study,we examined the geochemistry of Cenozoic basalts in southeast China.These basalts which are divided into four volcanic belts exhibit a DMM-EM2 mixing trend and spatial variations in Pb isotopes from inland(i.e.,thick lithosphere)to coastal(i.e.,thin lithosphere)regions.In contrast to the Pb isotopic variations,there are no spatial variations in Sr-Nd-Hf isotopes.Marked correlations between Pb isotopes and major elements(i.e.,Mg O and Si O_(2))suggest the continental lithospheric lid controlled their petrogenesis.Nonetheless,other factors are needed to explain the variations in Ti/Ti^(*)and Hf/Hf^(*)ratios,and Nd-Hf isotopes of the southeast China basalts.The increasing Pb isotope ratios from the inner to coastal regions are associated with decreases in CaO/Al_(2)O_(3) ratios and increases in FC3MS(FeO^(T)/CaO-3×Mg O/Si O_(2);in wt.%)values,indicating contributions from non-peridotite components in the mantle sources.The similarly depleted Nd-Hf isotopic compositions of the basalts from the three inner belts indicate these basalts have a similar origin,whereas the more enriched isotopic features of the basalts from the outer belt suggest their mantle source contains older recycled oceanic crust.Thus,source(i.e.,lithological)heterogeneity also had a significant role in controlling the geochemistry of these basalts.The DMM-EM2 mixing trend defined by the Pb isotopic compositions of continental intraplate basalts from southeast China was generated by variable degrees of melting of heterogeneous mantle that was controlled by the thickness of the continental lithospheric lid(i.e.,the melting pressure).This caused variable extents of melting of enriched components in the mantle sources of the basalts(i.e.,carbonated peridotite vs.pyroxenite).展开更多
A series of crystallization experiments have been carried out by using natural Emeishan Ti-rich hydrous basalts as starting materials at a pressure of 0.5 GPa and temperatures of 800-1000℃to constrain the origin of F...A series of crystallization experiments have been carried out by using natural Emeishan Ti-rich hydrous basalts as starting materials at a pressure of 0.5 GPa and temperatures of 800-1000℃to constrain the origin of Fe-Ti-V oxide ore deposits.Our experimental results demonstrate that the sandwich-and trellis-type ilmenite lamellae in titanomagnetite of layered intrusions can be formed by the reaction of earlier crystallized ilmenite and the evolved parental magma.During evolution of parental basaltic magma,the Fe-Ti oxide should be composed of titanomagnetite+ilmenite in the earlier stage,but changed to titanomagnetite+titanomagnetite-ilmenite intergrowth±ilmenite at the later stage.Accordingly,the Panzhihua Fe-Ti oxide ores,which are mainly composed of titanomagnetite,should be formed earlier than the adjacent gabbro,in which titanomagnetite-ilmenite intergrowth is the major form of the Fe-Ti oxide.展开更多
基金supported by the National Basic Research Program of China(No.2007CB411401)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KZCX2-YW-136)the National Natural Science Formation of China(No.40873028)
文摘The Binchuan area of Yunnan is located in the western part of the Emeishan large igneous province in the western margin of the Yangtze Block. In the present study, the Wuguiqing profile in thickness of about 1440 m is mainly composed of high-Ti basalts, with minor picrites in the lower part and andesites, trachytes, and rhyolites in the upper part. The picrites have relatively higher platinum- group element （PGE） contents （PGE=16.3-28.2 ppb）, with high Cu/Zr and Pd/Zr ratios, and low S contents （5.03-16.9 ppm）, indicating the parental magma is S-unsaturated and generated by high degree of partial melting of the Emeishan large igneous province （ELIP） mantle source. The slightly high Cu/Pd ratios （11 000-24 000） relative to that of the primitive mantle suggest that 0.007% sulfides have been retained in the mantle source. The PGE contents of the high-Ti basalts exhibit a wider range （~PGE=0.517-30.8 ppb）. The samples in the middle and upper parts are depleted in PGE and have ~Nd （260 Ma） ratios ranging from -2.8 to -2.2, suggesting that crustal contamination of the parental magma during ascent triggered sulfur saturation and segregation of about 0.446%-0.554% sulfides, and the sulfide segregation process may also provide the ore-forming material for the magmatic Cu-Ni-PGE sulfide deposits close to the studied basalts. The samples in this area show Pt- Pd type primitive mantle-normalized PGE patterns, and the Pd/Ir ratios are higher than that of the primitive mantle （Pd/Ir=l）, indicating that the obvious differentiation between Ir-group platinum- group elements （IPGE） and Pd-group platinum-group elements （PPGE） are mainly controlled by olivine or chromites fractionation during magma evolution. The Pd/Pt ratios of most samples are higher than the average ratio of mantle （Pd/Pt=0.55）, showing that the differentiation happened between Pt and Pd. The differentiation in picrites may be relevant to Pt hosted in discrete refractory Pt-alloy phase in the mantle; whereas the differentiation in the high-Ti basalts is probably associated with the fractionation of Fe-Pt alloys, coprecipitating with Ir-Ru-Os alloys. Some high-Ti basalt samples exhibit negative Ru anomalies, possibly due to removal of laurite collected by the early crystallized chromites.
基金financially supported by the National Natural Science Foundation of China(Nos.52204345 and 52474361)the Scientific Research Innovation Projects of Graduate Student of Jiangsu province,China(No.KYCX24_4184)。
文摘The large-scale production of high-Ti steels is limited by the formation of Ti-containing oxides or nitrides in steel-slag reactions during continuous casting.These processes degrade mold flux properties,clog submerged entry nozzles,form floaters in the molds,and produce various surface defects on the cast slabs.This review summarizes the effects of nonmetallic inclusions on traditional CaO-SiO_(2)-based(CS)mold fluxes and novel CaO-Al_(2)O_(3)-based(CA)low-or non-reactive fluxes containing TiO_(2),BaO,and B_(2)O_(3)additives to avoid undesirable steel,slag,and inclusion reactions,with the aim of providing a new perspective for research and practice related to balancing the lubrication and heat transfer of mold fluxes to promote smooth operation and reduce surface defects on cast slabs.For traditional CS mold flux,although the addition of solvents such as Na_(2)O,Li_(2)O,and B_(2)O_(3)can enhance flowability,steel-slag reactions persist,limiting the effectiveness of CS mold fluxes in high-Ti steel casting.Low-or non-reactive CA mold fluxes with reduced SiO_(2)content are a research focus,where adding other components can significantly change flux characteristics.Replacing CaO with BaO can lower the melting point and inhibit crystallization,allowing the flux to maintain good flowability at low temperatures.Replacing SiO_(2)with TiO_(2)can stabilize the viscosity and enhance heat transfer.To reduce the environmental impact,fluorides are replaced with components such as TiO_(2),B_(2)O_(3),BaO,Li_(2)O,and Na_(2)O for F-frce mold fluxes with similar lubrication,crystallization,and heat-transfer effects.When TiO_(2)replaces CaF_(2),it stabilizes the viscosity and enhances the heat conductivity,forming CaTiO_(3)and CaSiTiO_(5)phases instead of cuspidine to control crystallization.B_(2)O_(3)lowers the melting point and suppresses crystallization,forming phases such as Ca_(3)B_(2)O_(6)and Ca_(11)Si_(4)B_(2)O_(22).BaO introduces non-bridging oxygen to reduce viscosity and ensure flux flowability at low temperatures.However,further studies are required to determine the optimal mold flux compositions corresponding to the steel grades and the interactions between the various components of the mold flux.In the future,the practical application of new mold fluxes for high-Ti steel will become the focus of further verification to achieve a balance between lubrication and heat transfer,which is expected to minimize the occurrence of casting problems and slab defects.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB 41000000)the Civil Aerospace Pre-research Projects (D020202 and D020302)+2 种基金the National Natural Science Foundation of China (41773059, 41873076, 41803051, 41973060, 42073060, and 42173044)the National Key Research and Development Program of China (2021YFA0716100)the Minor Planet Foundation of China
文摘In December 2020, Chang’E-5(CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain, a great distance from those of Apollo and Luna missions. These young mare basalts bear critical scientific significance as they could shed light on the nature of the lunar interior(composition and structure) as well as the recent volcanism on the Moon. In this article, we investigated a CE-5 basalt sample(CE5 C0000 YJYX065) using a combination of state-of-art techniques, including high resolution X-ray tomographic microscopy(HR-XTM), energy dispersive X-ray spectroscopy(EDS)-based scanning electron microscope(SEM), and electron probe microanalysis(EPMA) to reveal its 3 D petrology and minerology.Our results show that this sample has a fine-to medium-grained subophitic texture, with sparse olivine phenocrysts setting in the groundmass of pyroxene, plagioclase, ilmenite and trace amounts of other phases. It has an extremely high ilmenite modal abundance(17.8 vol%) and contains a significant amount(0.5 vol%) of Ca-phosphate grains. The mineral chemistry is in excellent agreement with that of Apollo and Luna high-Ti basalts. The major phase pyroxenes also display strong chemical zoning with compositions following the trends observed in Apollo high-Ti basalts. Based on current data, we came to the conclusion that CE5 C0000 YJYX065 is a high-Ti mare basalt with a rare earth element(REE) enriched signature. This provides a rigid ground-truth for the geological context at the CE-5 landing site and clarifies the ambiguity inferred from remote sensing surveys.
基金supported by the National Natural Science Foundation of China(No.22278260)the Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry(No.KFKT2021-14)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology(No.KFKT2021-14).
文摘Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.
文摘This study investigates the compressive and tensile properties of basalt fiber-reinforced concrete (BFRC) after ultra-low-temperature freeze-thaw cycles. Scanning electron microscope (SEM) analysis was conducted to examine the deterioration mechanisms caused by freeze-thaw cycles and sulfate erosion. The results show that compressive and tensile strengths increase with basalt fiber dosage. The optimal dosage is 0.2%. With longer exposure to sulfate erosion, both strengths decline significantly. Basalt fibers effectively bridge cracks, control expansion, enhance compactness, and improve concrete performance. Ultra-low-temperature freeze-thaw cycles and sulfate erosion cause rapid crack growth. Sulfate erosion produces crystallization products and expansive substances. These fill cracks, create pressure, and damage the internal structure. Freezing and expansion forces further enlarge voids and cracks. This provides space for expansive substances, worsening concrete deterioration and reducing its performance.
基金supported by the National Natural Science Foundation of China(Nos.U22A20252 and 52173076)the Beijing Natural Science Foundation(Nos.Z240030 and L248023)the Liaoning Province Key Research and Development Project(No.2024JH2/102400046)。
文摘Sizing treatment is a suitable technique to modify the fiber-matrix interfaces without damage of inherent performance of fibers.In this work,sizing agents based on Janus particles(JPs)were utilized to enhance the interface of basalt fiber(BF)/poly(vinyl chloride)(PVC)composites.polystyrene/poly(butyl acrylate)(PS/PBA)@silica JPs were synthesized by seed emulsion polymerization and three different sizing agents were prepared for BF sizing treatment.JPs with organic soft sphere and inorganic hard hemisphere enhanced the interfaces through their amphiphilicity,chemical bonding and mechanical interlock.The mechanical properties of composite with JPs sizing treated BFs performed better when there was one JPs layer modified on the interface.According to the intermitting bonding and gradient modulus theory,JPs patterned interfaces are ideal transition layers between high modulus BF and low modulus PVC.
基金supported by the“Startup Grant for the University Teachers”of the University of Kerala.
文摘The role of mantle plume in the final stages of rifting of the East Gondwana crustal fragments remains equivocal with only limited evidence so far reported from the southern part of Peninsular India.Here,we report for the first time a suite of columnar basalts from the Mesoarchean Coorg Block in the Southern Granulite Terrain(SGT)of India and characterize these rocks through field,petrological,geo-chemical,and isotope geochronological studies.The basalts show porphyritic texture with phenocrysts of pyroxene and plagioclase embedded in fine groundmass.Geochemical data reveal tholeiitic flood basalt affinity with affinities of plume-related magmatism.The zircon U-Pb data of the rocks yield a weighted mean age of 137 Ma,thus corresponding to the Valanginian Age of the Early Cretaceous Period.We suggest the possible geochemical affinity of the studied rocks Kerguelen plume basalts which provide new insights into magmatism associated with the final stages of East Gondwana rifting.
基金supported by the National Natural Science Foundation of China(Grant No.52374192)the Henan Province Funds for Distinguished Young Youths(Grant No.242300421013)the Innovative Scientific Research Team Project of Henan Polytechnic University(Grant No.T2024-1).
文摘Mitigating climate change demands innovative solutions,and carbon sequestration technologies are at the forefront.Among these,basalt,a mafic volcanic rock packed with calcium,magnesium,and iron,emerges as a powerful candidate for carbon dioxide(CO_(2))sequestration through mineral carbonation.This method transforms CO_(2)into stable carbonate minerals,ensuring a permanent and environmentally safe storage solution.While extensive research has explored into basalt’s potential under high hydration conditions,the untapped promise of low water content scenarios remains largely unexplored.Our ground-breaking study investigates the mineral carbonation of basalt powder under low water condi-tions using supercritical CO_(2)(sc-CO_(2)).Conducted at 50℃ and 15 MPa with a controlled moisture content of 30%,our experiment spans various time points(0,7,14,21,and 28 days).Utilising advanced X-ray diffraction(XRD)and scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM-EDS),we unveil the mineralogical and morphological transformations.The results are striking:even under low water conditions,basalt efficiently forms valuable carbonate minerals such as calcite,siderite,magnesite,and ankerite.The carbonation efficiency evolves over time,reflecting the dynamic transfor-mation of the basalt matrix.These findings offer pivotal insights into optimising CO_(2)sequestration in basalt under low hydration,marking a significant leap toward sustainable carbon capture and storage.
基金supported by the National Natural Science Foundation of China(42172010,42372071,41102037)。
文摘The Longshan orogenic belt is located in the southwestern margin of Ordos Basin at the junction zone between the Western Qinling and Northern Qilian orogenic belt.Voluminous Early Paleozoic magmatism in this area is of key significance for determining the Early Paleozoic tectonic evolution and deep crust-mantle structure.Previous studies mainly focused on the Paleozoic granites;the coeval mafic rocks in this area are still poorly understood.A set of Late Silurian intraplate tholeiitic basalts has been discovered in Longshan area,providing key evidence for the mantle source and deep geodynamic background in this area.The Late Silurian Angou basalt has similar geochemical features as intraplate tholeiitic basalt,with high Na_(2)O/K_(2)O ratios(5.22-8.25),enriched in large ion lithophile elements and LREE.In combination with their relatively evolved Sr-Nd isotopic composition[^(87)Sr/^(86)Sr(i)=0.7128-0.7140;ε_(Nd)(t)=-5.55 to-3.40],it is suggested that it originated from decompression melting of metasomatized enriched mantle in extensional setting.These results indicate that the mantle source in the junction zone of the West Qinling-North Qilian orogenic belt evolved from depleted to enriched with the continuation of Proto-Tethys subduction from the Cambrian to the Silurian.These results are of great significance to understanding the genesis of contemporaneous granite and the crust-mantle interaction in the junction zone between the Western Qinling and Northern Qilian orogenic belt.
基金The National Natural Science Foundation of China under contract No.42030502the Guangxi Scientific Projects under contract Nos.AD17129063,AA17204074,and 2025GXNSFAA069324the NSFC project under contract No.42166003。
文摘As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scientific drilling project on the Xisha Islands in the northwestern SCS.It penetrates the thick reef limestone and reaches basaltic pyroclastic rocks.This study presents the whole-rock and olivine compositions of the basaltic volcaniclastic rocks from Well CK-2.These rocks exhibited ocean island basalt signatures characterized by the enrichment of light rare earth elements and high-field-strength elements.Compared with partial melting products derived from mantle peridotite,whole-rock compositions showed elevated Fe/Mn and Zn/Fe mass ratios.Additionally,olivines were characterized by a lower Ca content,higher Ni content,elevated Fe/Mn mass ratios,and moderate Mn/Zn mass ratios compared to those crystallized from peridotitic melts.The compositions of both the whole-rock and olivine phenocrysts indicate the presence of pyroxenite in the mantle source,which likely formed through the reaction of recycled oceanic crust with the surrounding mantle peridotite.Using the olivine-liquid Mg-Fe exchange thermometer,this study derived mantle potential temperatures(T_(p))ranging from 1502℃to 1756℃,which is consistent with those of plume-related ocean island basalts.Furthermore,the basaltic volcaniclastic rocks exhibit low H_(2)O contents(0.01%–1.47%),which were significantly lower than those found in the primary magmas of Large Igneous Provinces.These results suggest that the basaltic volcaniclastic rocks on the Xisha Islands originated from a volatile-poor mantle plume source.
基金Project(2021YFC2900200)supported by the National Key Research and Development Project of ChinaProject(20230203114SF)supported by the Key Research and Development Project of Jilin Province,China。
文摘Basalt fibers/7075 aluminum matrix composites were studied to meet the demand of aluminum alloy drill pipes for material wear resistance.The composites with different basalt fiber additions were prepared by hot pressed sintering and hot extrusion.The mechanical properties as well as friction and wear properties of the composites were studied by microstructure analysis,tensile experiments,friction and wear experiments.The results showed that basalt fibers were oriented and uniformly distributed and led to local grain refinement in the alloy matrix.The hardness and elongation of the composites were improved.The friction coefficient of the composites increased and then decreased,and the maximum wear depth and wear amount decreased,then increased,then decreased again with the growth of basalt fiber addition.Meanwhile,the inclusion of basalt fibers mitigated the uneven wear of the extruded 7075 aluminum alloy.The value of wear depth difference of 7075-0.2BF was the smallest,and that of 7075-2.0BF was close to it.The maximum wear depth and wear volume the 7075-0.2BF and 7075-2.0BF were also the smallest.The inhibition of uneven wear by basalt fibers enhanced of wear resistance for 7075 aluminum alloy,which has reference significance for improving the performance of aluminum alloy drill pipes.
基金supported by National Natural Science Foundation of China(No.52304344)Postdoctoral Science Foundation of China(No.2024T171095)Cooperation Project of Pangang Group.Author information。
文摘The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+SiO_(2))mass ratio while the total iron content is reduced.Thermodynamic analysis indicates that the increase in(CaO+SiO_(2))mass ratio from 15.0 to 22.5 wt.%contributes to the formation of liquid phase,especially silico-ferrite of calcium and aluminum(SFCA).In addition,the formation of perovskite is inhibited and liquid phase fluidity is improved.The porosity of sinter matrix is reduced by 34.5%and SFCA amount is increased by 47.2%when(CaO+SiO_(2))mass ratio is increased from 15.0 to 18.0 wt.%.With the further increase in(CaO+SiO_(2))mass ratio,the structure of sinter matrix is too dense and the improved extent of SFCA amount is increasingly low.The appropriate(CaO+SiO_(2))mass ratio should be 18.0 wt.%overall.Under this condition,sinter matrix strength is greatly improved by over 13.5%compared with the base case and the total iron content can be maintained at about 49 wt.%.
基金support for this research from the Fundamental Research Funds for the National Natural Science Foundation of China (Grant Nos. 51978588, 52078434, and 52368065)the China Scholarship Council (Grant No. 202107000077)UKRI Engineering and Physical Science ResearchCouncil (EPSRC) for the financial sponsorship of Re4Rail project (Grant No. EP/Y015401/1)
文摘Foamed concrete has been used to address the issue of differential settlement in high-speed railway subgrades in China.However,to enhance crack resistance,reinforcement is still necessary,and further research is required to better understand the performance of foamed concrete in subgrade applications.To this end,a series of tests—including uniaxial compres-sive and dynamic triaxial tests—were conducted to comprehensively examine the effects of basalt fiber reinforcement on the mechanical properties of foamed concrete with densities of 700 and 1000 kg/m3.Additionally,a full-scale model of the foamed concrete subgrade was established,and simulated loading was applied.The diffusion patterns of dynamic stress and dynamic acceleration within the subgrade were explored,leading to the development of experimental formulas to calculate the attenuation coefficients of these two parameters along the depth and width of the subgrade.Furthermore,the dynamic displacement and cumulative settlement were analyzed to evaluate the stability of the subgrade.These findings provide valuable insights for the design and construction of foamed concrete subgrades in high-speed rail systems.The outcomes are currently under consideration for inclusion in the code of practice for high-speed rail restoration.
基金supported by the National Key Research and Development Project(Grant No.2023YFE0110900)the National Natural Science Foundation of China(Grant No.42320104003)the Shanghai Pujiang Programme(Grant No.23PJD105).
文摘Although supercritical carbon dioxide(SC-CO_(2))fracturing shows tremendous potential for maximizing injection efficiency and enhancing storage volumes,few investigations have been reported on the SC-CO_(2) fracturing characteristics of tight basalts and the reactions between fractured basalt and SC-CO_(2).In this study,hydraulic fracturing experiments were conducted on cylindrical basalt specimens using water and SC-CO_(2) as fracturing fluids.Geometric parameters were proposed to characterize the fracture morphologies based on the three-dimensional(3D)reconstructions of fracture networks.The rock slices with induced fractures after SC-CO_(2) fracturing were then processed for fluid(deionized water/SC-CO_(2))-basalt reaction tests.The experimental results demonstrate that SC-CO_(2) fracturing can induce complex and tortuous fractures with spatially dispersed morphologies.Other fracturing behaviors accompanying the acoustic emission(AE)signals and pump pressure changes show that the AE activity responds almost simultaneously to variation in the pump pressure.The fractured basalt blocks exposed to both SC-CO_(2) and water exhibit rough and uneven surfaces,along with decreased intensities in the element peaks,indicating that solubility trapping predominantly occurs during the early injection stage.The above findings provide a laboratory research basis for understanding the fracturing and sequestration issues related to effective CO_(2) utilization.
基金funded by National natural Science Foundation of China(41973058 and 42473052)the B-type Strategic Priority Research Program of Chinese Academy of Sciences(XDB41020305)National Key and Development Program of China(2024YFF0807500).
文摘The size of basalt fragments in Chang’E-5(CE-5)regolith are small(<6 mm^(2)),resulting in large variation on the estimated bulk composition of CE-5 basalt.For example,the estimated TiO_(2) content of CE-5 basalt ranges from 3.7 wt% to 12.7 wt% and the Mg#(molar percentage of Mg/[Mg+Fe])also shows a wide range(26.2-42.4).Preliminary experimental studies have shown that these geochemical characteristics of CE-5 basalt are critical for investigating the crystallization sequence and formation mechanism of its parent magma.This study presents new experimental data on the distribution coefficient of titanium between pyroxene and lunar basaltic magma(D_(Ti)^(Px/melt)).Combining with available literature data,we confirm that D_(Ti)Px/melt is affected by crystallization conditions such as pressure and temperature,but it is mainly controlled by the CaO content of pyroxene.Comparing with previous experimental results under similar conditions,we parameterized the effect as D_(Ti)^(Px/Melt)=D_(Ti)^(Px/Melt)=-0.0005X_(Cao)^(2)+0.0218X_(CaO)+0.0425(R^(2)=0.82),where X_(CaO) is the CaO content in pyroxene in weight percentage.The new experimental results suggest that pyroxene with high TiO_(2) content(>2.5 wt%)in CE-5 basalt is not a product of equilibrium crystallization,and the CaO content in pyroxene is also affected by cooling rate of its parent magma.The TiO_(2) content in the CE-5 parent magma is estimated to be about 5 wt% based on the Mg# of pyroxene and its calculated CaO content,which is consistent with those estimated from olivine grains.
基金supported by the National Natural Science Foundation of China(No.41906051)the National Key R&D Program of China(No.2018YFE0202402)+1 种基金sponsored by the Fundamental Research Funds for the Central Universities(Tongji University)(No.22120210525)Shanghai Pilot Program for Basic Research。
文摘Continental intraplate basalts form by partial melting of the mantle,and can provide important constraints on mantle heterogeneity.However,due to the thick overlying continental lithosphere,the origins of the geochemical characteristics of continental intraplate basalts are controversial.In this study,we examined the geochemistry of Cenozoic basalts in southeast China.These basalts which are divided into four volcanic belts exhibit a DMM-EM2 mixing trend and spatial variations in Pb isotopes from inland(i.e.,thick lithosphere)to coastal(i.e.,thin lithosphere)regions.In contrast to the Pb isotopic variations,there are no spatial variations in Sr-Nd-Hf isotopes.Marked correlations between Pb isotopes and major elements(i.e.,Mg O and Si O_(2))suggest the continental lithospheric lid controlled their petrogenesis.Nonetheless,other factors are needed to explain the variations in Ti/Ti^(*)and Hf/Hf^(*)ratios,and Nd-Hf isotopes of the southeast China basalts.The increasing Pb isotope ratios from the inner to coastal regions are associated with decreases in CaO/Al_(2)O_(3) ratios and increases in FC3MS(FeO^(T)/CaO-3×Mg O/Si O_(2);in wt.%)values,indicating contributions from non-peridotite components in the mantle sources.The similarly depleted Nd-Hf isotopic compositions of the basalts from the three inner belts indicate these basalts have a similar origin,whereas the more enriched isotopic features of the basalts from the outer belt suggest their mantle source contains older recycled oceanic crust.Thus,source(i.e.,lithological)heterogeneity also had a significant role in controlling the geochemistry of these basalts.The DMM-EM2 mixing trend defined by the Pb isotopic compositions of continental intraplate basalts from southeast China was generated by variable degrees of melting of heterogeneous mantle that was controlled by the thickness of the continental lithospheric lid(i.e.,the melting pressure).This caused variable extents of melting of enriched components in the mantle sources of the basalts(i.e.,carbonated peridotite vs.pyroxenite).
基金supported by funds from the National Key Research and Development Program of China (No.2016YFC0600204)the National Natural Science Foundation of China (Nos.41530211 and41872061)+1 种基金the National Key Basic Research Program of China (No.2015CB856101)the MOST Special Fund from the State Key Laboratory of GPMR (No.MSFGPMR02-2)
文摘A series of crystallization experiments have been carried out by using natural Emeishan Ti-rich hydrous basalts as starting materials at a pressure of 0.5 GPa and temperatures of 800-1000℃to constrain the origin of Fe-Ti-V oxide ore deposits.Our experimental results demonstrate that the sandwich-and trellis-type ilmenite lamellae in titanomagnetite of layered intrusions can be formed by the reaction of earlier crystallized ilmenite and the evolved parental magma.During evolution of parental basaltic magma,the Fe-Ti oxide should be composed of titanomagnetite+ilmenite in the earlier stage,but changed to titanomagnetite+titanomagnetite-ilmenite intergrowth±ilmenite at the later stage.Accordingly,the Panzhihua Fe-Ti oxide ores,which are mainly composed of titanomagnetite,should be formed earlier than the adjacent gabbro,in which titanomagnetite-ilmenite intergrowth is the major form of the Fe-Ti oxide.
