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Do we really need to drill through the intact ocean crust? 认领 引用 被引量：2
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作者 Yaoling Niu 《Geoscience Frontiers》 SCIE CAS CSCD 2025年第1期47-63,共17页
We must persevere to drill through the intact ocean crust to fully address fundamental questions towards completion of the plate tectonics theory.The primary questions include:what is the ocean crust made up of,how th... We must persevere to drill through the intact ocean crust to fully address fundamental questions towards completion of the plate tectonics theory.The primary questions include:what is the ocean crust made up of,how thick is it and what is the petrological nature of the crust-mantle boundary(i.e.,Mohorovičićdiscontinuity or Moho)?These questions may sound naive because they are widely believed to be well-understood facts,but they are not.Correctly,our current knowledge remains incomplete,and some popular misperceptions come from interpretations based on convenient assumptions.One assumption is that the ocean crust inferred from seismic data is of magmatic origin.Testing this assumption is a principal motivation of Project Mohole(1957-1966),attempting to drill intact ocean crust across the Moho into the mantle.Project Mohole failed because of its high cost,engineering challenges and insufficient tries,but the technologies developed made subsequent ocean drilling successful.However,answers to the original questions remain unsatisfactory.For example,seismic crust interpreted to be of magmatic origin is shown to have globally uniform thickness of 6.0±1.0 km,but crust with such thickness at many slow-spreading ridge segments is dominated by serpentinized mantle peridotites exposed on seafloors.Therefore,the popular view on ocean ridge magmatism must be re-examined,which needs intact ocean crust drilling into the mantle.Drilling at geologically simple sites in the fast-spreading Pacific seafloor is most promising.The US-led D/V JOIDES Resolution that has well served the scientific ocean drilling since 1985 is to retire by the end of 2024,but timely the Chinese geoscience community wishes to continue this international endeavor using the purpose-built D/V Meng Xiang to be in service in 2025.The international community is to gather in November 24-27,2024,Guangzhou,China,to discuss strategies on where and how to successfully drill intact ocean crust across the Moho in coming years. 展开更多
关键词 Ocean crust formation Ocean crust makeup and thickness varication Hess-type ocean crust Nature of the oceanic Moho Scientific ocean drilling
Petrogenesis of late Cretaceous high Ba-Sr granodiorites,SE Lhasa block,China:implications for the reworking of juvenile crust and continental growth 认领 引用 被引量：1
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作者 Li-Hang Lin Ren-Zhi Zhu +4 位作者 Shao-Cong Lai Jiang-Feng Qin Yu Zhu Shao-Wei Zhao Min Liu 《Acta Geochimica》 EI CAS CSCD 2025年第1期86-111,共26页
The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains controversial.Identifying the Late Cretaceous high Ba-Sr granodiorites in the SE Lhasa... The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains controversial.Identifying the Late Cretaceous high Ba-Sr granodiorites in the SE Lhasa Block could potentially provide valuable insights into the continent evolution of the Qinghai-Tibet Plateau.Zircon U-Pb ages suggest that the granodiorites were emplaced at 87.32±0.43 Ma.Geochemically,the high Ba-Sr granodiorites are characterized by elevated K2O+Na2O contents(8.18-8.73 wt%)and K2O/Na2O ratios(0.99-1.25,mostly>1),and belong to high-K calc-alkaline to shoshonitic series.The Yonglaga granodiorites show notably high Sr(653-783 ppm)and Ba(1346-1531 ppm)contents,plus high Sr/Y(30.92-38.18)and(La/Yb)N(27.7-34.7)ratios,but low Y(20.0-22.8 ppm)and Yb(1.92-2.19 ppm)contents with absence of negative Eu anomalies(δEu=0.83-0.88),all similar to typical high Ba-Sr granitoids.The variable zirconεHf(t)values of-4.58 to+12.97,elevated initial87Sr/86Sr isotopic ratios of 0.707254 to 0.707322 and lowεNd(t)values of-2.8 to-3.6 with decoupling from the Hf system suggest that a metasomatized mantle source included significant recycled ancient materials.The occurrence of such high Ba-Sr intrusions indicates previous contributions of metasomatized mantle-derived juvenile material to the continents,which imply the growth of continental crust during the Late Cretaceous in the SE Lhasa.Together with regional data,we infer that the underplated mafic magma provides a significant amount of heat,which leads to partial melting of the juvenile crust.The melting of the metasomatized mantle could produce a juvenile mafic lower crust,from which the high Ba-Sr granitoids were derived from reworking of previous mafic crust during the Late Cretaceous(ca.100-80 Ma)in the SE Lhasa. 展开更多
关键词 Late Cretaceous High Ba-Sr granodiorites SE Lhasa Growth of continental crust Juvenile crust
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Origin of the Cretaceous Biluocuo Low-Mg Trachy-Andesites in the Southern Qiangtang Block:Implications for Crust-Mantle Interactions and the Precambrian Basement 认领 引用
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作者 JI Changjun CHEN Chong +3 位作者 ZOU Yuanbing CHEN Yun ZHOU Lianfeng ZHU Jiang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2025年第3期761-773,共13页
The Cretaceous andesites were discovered in the Biluocuo area,and provided key records to understand the late Mesozoic geodynamic evolution and crustal basement for the southern Qiangtang block in the central Xizang.I... The Cretaceous andesites were discovered in the Biluocuo area,and provided key records to understand the late Mesozoic geodynamic evolution and crustal basement for the southern Qiangtang block in the central Xizang.In this study,we present a detailed study of zircon U-Pb dating,major and trace elemental composition,and Sr-Nd-Hf isotopes for the Biluocuo trachy-andesites.The trachy-andesites yielded zircon U-Pb ages at ca.97 Ma,and exhibited SiO2contents ranging from 55.92 to 69.04 wt%,low TiO2contents(0.37 to 0.75 wt%)and low Mg~#values(18.6 to 53.7),suggesting that they belong to high-K calc-alkaline series.They showed adakitic signatures,such as high Sr/Y ratios(almost 24 to 55)and low Y(15 kbar).The samples have initial Sr isotopic ratios of 0.70963 to 0.70964,εNd(t)values of-4.7 to-4.6,and zirconεHf(t)values of-1.2 to+1.3 with two-stage Hf model ages of 0.95 to 1.09 Ga.Elemental and Sr-Nd-Hf isotopic signatures suggest that the trachy-andesites were derived from the partial melting of the thickened lower crust with involvement of metasomatized mantle components.Combined with coeval highMg andesites,we proposed that underplating of mantle induced melting of the lower crust at ca.97 Ma in the southern Qiangtang block,following by lithospheric delamination.Inherited/xenocrystic zircons from the trachy-andesites revealed magmatic activities at 2562 Ma,1850-1804 Ma,1768-1665 Ma,1043-935 Ma,851-736 Ma and 642-540 Ma.There is a Precambrian crustal basement in the southern Qiangtang block,which may have experienced the assembly and break-up of the Columbia,Rodinia,and Gondwana supercontinents. 展开更多
关键词 geochemistry low-Mg adakitc rocks volcanic crust-mantle interaction ancient crust Qiangtang block
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Insights into selective leaching of rare earths from weathered crust elution-deposited rare earth ore using magnesium sulfate 认领 引用 被引量：4
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作者 Jiaxin Pan Qi Guo +6 位作者 Longsheng Zhao Zheng Li Xiaowei Huang Zongyu Feng Depeng Liu Xudong Zheng Weisheng Wei 《Journal of Rare Earths》 SCIE EI CAS CSCD 2025年第5期1057-1066,共10页
In this paper,a multi-stage leaching process for the weathered crust elution-deposited rare earth ore was proposed using MgSO4as a leaching agent.The results indicate that with increasing the concentration of MgSO_... In this paper,a multi-stage leaching process for the weathered crust elution-deposited rare earth ore was proposed using MgSO4as a leaching agent.The results indicate that with increasing the concentration of MgSO4from 0.5 wt%-1.0 wt%to 2.0 wt%-4.0 wt%,the peak concentrations of rare earths increase from 1.87 to 3.59 to 5.49-10.21 g/L,and the collection periods of leach solution are sho rtened from 0.85 to 1.54 to 0.31-0.47(liquid-to-ore ratio).When the rare earth ore is leached with leaching agent solution with high initial pH(3.0-5.0),the rare earths and aluminum are predominantly leached by Mg2+instead of H+.However,H+participate in the leaching process of rare earths and aluminum at lower initial pH(1.5-3.0)of the leaching agent solution.Especially,when the initial pH of leaching agent solution is 2.0,a large amount of aluminum is leached when the liquid-to-ore ratio is greater than 1.2.Based on the above insights,increasing the initial pH(3.0-5.0)of leaching agent solution in the injection stage using high-concentration MgSO4(>1.0 wt%)can increase the peak concentration of rare earths in the leach solution and shorten the collection period.However,in the injection stage using low MgSO4concentration(<1.0 wt%),an initial pH of leaching agent solution of 2.0 is selected to reduce the leaching amount of aluminum and the consumption of MgSO4.Comparing to the Leaching process using constant MgSO4concentration(2.0 wt%,initial pH of 5.0),the leaching efficiency of rare earths using a multi-stage leaching process is approximately equal(about 94.6%)under optimal conditions.The leaching amount of aluminum is reduced by 16.9%.The consumption of MgSO4is reduced by 67.1%. 展开更多
关键词 Weathered crust elution-deposited rare earth ore Column leaching Aluminum Rare earths Magnesium sulfate
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High-resolution upper crustal S-wave velocity structure and seismicity distribution around the junction of the Zemuhe and Xiaojiang Fault Zones, Southwest China 认领 引用 被引量：4
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作者 Xin Liu HuaJian Yao +2 位作者 CuiPing Zhao Ying Liu Song Luo 《Earth and Planetary Physics》 EI CSCD 2025年第2期225-238,共14页
The Anninghe–Zemuhe Fault and the Xiaojiang Fault are critical active faults along the middle-eastern boundary of the South Chuan–Dian Block. Many researchers have identified these faults as potential strong-earthqu... The Anninghe–Zemuhe Fault and the Xiaojiang Fault are critical active faults along the middle-eastern boundary of the South Chuan–Dian Block. Many researchers have identified these faults as potential strong-earthquake risk zones. In this study, we leveraged a dense seismic array to investigate the high-resolution shallow crust shear wave velocity(Vs) structure beneath the junction of the Zemuhe Fault Zone and the Xiaojiang Fault Zone, one of the most complex parts of the eastern boundary of the South Chuan–Dian Block. We analyzed the distribution of microseismic events detected between November 2022 and February 2023 based on the fine-scale Vs model obtained. The microseismicity in the study region was clustered into three groups, all spatially related to major faults in this region. These microseismic events indicate near-vertical fault planes, consistent with the fault geometry revealed by other researchers.Moreover, these microseismic events are influenced by the impoundment of the downstream Baihetan Reservoir and the complex tectonic stress near the junction of the Zemuhe Fault Zone and the Xiaojiang Fault Zone. The depths of these microseismic events are shallower in the junction zone, whereas moving south along the Xiaojiang Fault Zone, the microseismic events become deeper.Additionally, we compared our fine-scale local Vs model with velocity models obtained by other researchers and found that our model offers greater detail in characterizing subsurface heterogeneity while demonstrating improved reliability in delineating fault systems. 展开更多
关键词 Zemuhe–Xiaojiang Fault Zone shallow crust S-wave velocity ambient noise tomography microseismicity
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Leaching of rare earths and aluminum in weathered crust elutiondeposited rare earth ore using magnesium sulfate:Effect of aluminum content in leaching agent solution 认领 引用 被引量：1
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作者 Depeng Liu Weiqiang Yin +3 位作者 Zheng Li Jiaxin Pan Longsheng Zhao Chunmei Wang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2025年第1期191-198,I0007,共8页
Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore(WCED-REO).Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO.T... Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore(WCED-REO).Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO.The effects of pH,MgSO4 concentration and Al3+concentration of the leaching agent solution on the column leaching behaviors of WCED-REO using magnesium sulfate were investigated.Experimental data show that controlling the MgSO4 concentration to 0.15 mol/L,pH of the leaching agent solution to 2,the leaching amount of aluminum from the rare earth ore gradually decreases with the increase of Al3+concentration in the leaching agent solution,indicating that Al3+in the leaching agent solution may act as leaching agent to participate in the ion exchange of RE3+,but the leaching amounts of rare earths change insignificantly as the Al3+concentration is increased.Increasing the MgSO4 concentration is beneficial to the leaching of aluminum,and when the Al3+concentration is 0.04 mol/L(Al accumulation),the amount of Al3+leached from the rare earth ore increased gradually with increasing the MgSO4 concentration.The pH of the leaching agent solution has a significant influence on the leaching of aluminum in the rare earth ore,and the leaching amount of aluminum from the rare earth ore increases gradually with decreasing the pH.When the Al3+conce ntration is 0.04 mol/L(Al accumulation)and the pH of the leaching agent solution is above 2.0,the aluminum in the leaching agent solution can be back-adsorbed onto the rare earth ore,and the amount of the back-adsorbed Al3+increases with increasing the pH of the leaching agent solution.The injection rate of the leaching agent solution has slight effect on the leaching behavior of rare earths and aluminum.In summary,leaching of Al3+and consumption of MgSO4 can be reduced by regulating the accumulation of aluminum,MgSO4 concentration and pH. 展开更多
关键词 Weathered crust elution-deposited rare earth ore Rareearths Magnesium sulfate Rare earth leaching Aluminum Back-adsorption
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Artificial cyanobacteria crusts can improve soil fertility and plant growth in a semi-arid area,northern China 认领 引用 被引量：1
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作者 JING Haimeng ZHOU Nan +1 位作者 TANTAI Yu ZHAO Yunge 《Journal of Arid Land》 SCIE CSCD 2025年第6期808-822,共15页
Artificial cyanobacteria crusts are formed by inoculating soil with cyanobacteria.These crusts help prevent soil erosion and restore soil functionality in degraded croplands.However,how fast the artificial cyanobacter... Artificial cyanobacteria crusts are formed by inoculating soil with cyanobacteria.These crusts help prevent soil erosion and restore soil functionality in degraded croplands.However,how fast the artificial cyanobacteria crusts can be formed is a key issue before their practical application.In addition,the effects of artificial cyanobacteria crusts on soil nutrients and plant growth are not fully explored.This study analyzed the effect of inoculation of cyanobacteria from local biological soil crusts on soil nutrients and Pak-choi(Brassica campestris L.ssp.Chinensis Makino var.communis Tsen et Lee;Chinese cabbage)growth in a cropland,northern China through field experiments by comparing with no fertilizer.The results showed that artificial cyanobacteria crusts were formed on the 18th d after inoculation with a coverage of 56.13%,a thickness of 3.74 mm,and biomass of 22.21μg chla/cm2.Artificial cyanobacteria crusts significantly improved the soil organic matter(SOM),NO3--N,total nitrogen(TN)contents,and the activities of sucrase,alkaline phosphatase,urease,and catalase enzymes of plants on the 50th d after inoculation.Additionally,artificial cyanobacteria crusts led to an increase in plant biomass,improved root morphology,and raised the phosphorus and potassium contents in the plants.Furthermore,the biomass of plant grown with artificial cyanobacteria crusts was comparable with that of grown with chemical fertilizer.The study suggested that,considering plant biomass and soil nutrients,it is feasible to prevent wind erosion in the cropland of arid and semi-arid areas by inoculating cyanobacteria crusts.This study provides new perspectives for the sustainable development and environmental management of cropland in arid and semi-arid areas. 展开更多
关键词 artificial cyanobacteria crusts wind erosion soil fertility plant growth soil enzyme
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Five-Stage Model of the Palaeozoic Crustal Evolution in Xinjiang 认领 引用 被引量：2
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作者 LIU Dequan TANG Yanling ZHOU Ruhong 《Acta Geologica Sinica(English Edition)》 SCIE CAS 1998年第4期339-349,共11页
Abstract: The great majority of the Palaeozoic orogenic belts of Central Asia are of the intercontinental type, whose evolution always follows a five-stage model, i.e. the basal continental crust-extensional transitio... Abstract: The great majority of the Palaeozoic orogenic belts of Central Asia are of the intercontinental type, whose evolution always follows a five-stage model, i.e. the basal continental crust-extensional transitional crust-oceanic crust-convergent transitional crust-new continental crust model. The stage for the extensional transitional crust is a pretty long, independent and inevitable phase. The dismembering mechanism of the basal continental crust becoming an extensional continental crust is delineated by the simple shear model put forward by Wernike (1981). The continental margins on the sides of a gently dipping detachment zone and moving along it are asymmetric: one side is of the nonmagmatic type and the other of the magmatic type with a typical bimodal volcanic formation. In the latter case, however, they were often confused with island arcs. This paper discusses the five-stage process of the crustal evolution of some typical orogenic belts in Xinjiang. 展开更多
关键词 crustal evolution extensional transitional crust oceanic crust new continental crust five-stage model Xinjiang
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Buried Cobalt-rich Ferromanganese Crusts from Weijia Guyot and their Implications for Pacific Plate Motion 认领 引用
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作者 ZHAO Bin HE Gaowen +12 位作者 JIANG Yuhan LIU Shijia CHEN Si DENG Yinan YANG Yong REN Jiangbo MA Weilin ZHANG Limin WANG Haifeng YANG Kehong DENG Xianze CHEN Qing ZHANG Ganglan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2025年第5期1344-1354,共11页
Weijia Guyot,located in the western Pacific Ocean,has become a research focus due to its abundant cobalt-rich ferromanganese(Fe-Mn)crusts.While most studies on Fe-Mn crusts on seamounts have focused on the exposed var... Weijia Guyot,located in the western Pacific Ocean,has become a research focus due to its abundant cobalt-rich ferromanganese(Fe-Mn)crusts.While most studies on Fe-Mn crusts on seamounts have focused on the exposed variety,less attention has been paid to potential buried crusts.This study presents a preliminary geochemical and chronological study of buried Fe-Mn crusts at Weijia Guyot.The findings suggest that these buried crusts began to form around 57.5 Ma and ceased growing at approximately 46.3 Ma.Following the formation of Weijia Guyot through volcanic eruption,it did not experience continuous and steady subsidence to its current depth.Instead,an exhumation process took place from deep to shallow depths between 46.3 and 11.6 Ma.This process brought the Fe-Mn crusts into shallow water environments,halting their growth.During this time,Weijia Guyot was located near the equatorial Pacific Ocean and was exposed to an extended period of phosphatization.This exposure led to a depletion of key metallogenic elements,such as Co,Ni and Cu,within the Fe-Mn crusts,while P2O5 and CaO levels increased significantly.Since the Middle Miocene,the crusts have been progressively buried by pelagic sediments. 展开更多
关键词 buried cobalt-rich ferromanganese crusts growth rate geochronology seamount evolution Weijia Guyot western Pacific Ocean
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Effects of biological soil crusts on plant growth and nutrient dynamics in the Minqin oasis-desert ecotone,Northwest China 认领 引用
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作者 KANG Jianjun YANG Fan +1 位作者 ZHANG Dongmei DING Liang 《Journal of Arid Land》 SCIE CSCD 2025年第1期130-143,共14页
Biological soil crusts(BSCs)play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas.However,the specific effects of BSCs on growth status and nutrient accumulation... Biological soil crusts(BSCs)play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas.However,the specific effects of BSCs on growth status and nutrient accumulation of plants are still unclear in different arid areas.This study analyzed the effects of three different BSCs treatments(without crust(WC),intact crust(IC),and broken crust(BC))on the growth,inorganic nutrient absorption,and organic solute synthesis of three typical desert plants(Grubovia dasyphylla(Fisch.&C.A.Mey.)Freitag&G.Kadereit,Nitraria tangutorum Bobrov,and Caragana koraiensis Kom.)in the Minqin desert-oasis ecotone of Northwest China.Results showed that the effects of three BSCs treatments on seed emergence and survival of three plants varied with seed types.The IC treatment significantly hindered the emergence and survival of seeds,while the BC treatment was more conducive to seed emergence and survival of plants.BSCs significantly promoted the growth of three plants,but their effects on plant growth varied at different stages of the growth.Briefly,the growth of G.dasyphylla was affected by BSCs in early stage,but the effects on the growth of G.dasyphylla significantly weakened in the middle and late stages.However,the growth of N.tangutorum and C.koraiensis only showed differences at the middle and late stages,with a significant enhancement in growth.Analysis of variance showed that BSCs,plant species,growth period,and their interactions had significant effects on the biomass and root:shoot ratio of three plants.BSC significantly affected the nutrients absorption and organic solute synthesis in plants.Specifically,BSCs significantly promoted nitrogen(N)absorption in plants and increased plant adaptability in N poor desert ecosystems,but had no significant effects on phosphorus(P)absorption.The effects of BSCs on inorganic nutrient absorption and organic solute synthesis in plants varied significantly among different plant species.The results suggest that BSCs have significant effects on the growth and nutrient accumulation of desert plants,which will provide theoretical basis for exploring the effects of BSCs on desert plant diversity,biodiversity conservation,and ecosystem management measures in arid and semi-arid areas. 展开更多
关键词 biological soil crusts(BSCs) desert oasis desert plants growth nutrient accumulation
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Metal accumulation potential in three types of moss crusts and soil contamination assessment 认领 引用
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作者 WANG Dengfu WU Qimei ZHANG Zhaohui 《Journal of Mountain Science》 SCIE CSCD 2025年第4期1405-1414,共10页
Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentration... Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentrations of moss crusts,and soil contamination indices in Wachangping bauxite tailing areas in Guizhou Province,China were measured and analyzed.In a total of 40 species belonging to 19 genera and 12 families of moss in the study areas,Ditrichum flexicaule(Schwaegr.)Hamp.(DF),Oxystegus cylindricus(Brid.)Hilp.(OC),and Ditrichum brevidens Nog.(DB)are the dominant moss crusts.Moss species diversity in different habitats has a certain regularity:waste residues areaDF>OC.Single factor pollution index(Ps)and Nemero comprehensive pollution index(Pc)of six metal are much greater than 3,and the index of geoaccumulation(Igeo)(1geo<5)reveals that the soil environment is at moderately to seriously contaminated levels.Principal components analysis(PCA)shows that there is no significant correlation between p H value,and metal contents(Al,Mg,Fe,K and Ti),soil temperature(ST)and metal contents(Al,Mg,Fe,K and Ti).Soil humidity(SH)is negatively correlated with metal contents(Al,Mg,Fe,K and Ti).These three environmental factors have little effect on the distribution of metal.Result also reflects that DB moss is readily able to both tolerate and accumulate metal,which makes it a suitable bioindicator of multiple metal contamination in Wachangping bauxite tailing areas. 展开更多
关键词 Bauxite tailing areas(BTAS) Moss crusts Accumulation potential Metal Soil contamination
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Upper crustal azimuthal anisotropy and seismogenic tectonics of the Hefei segment of the Tan-Lu Fault Zone from ambient noise tomography 认领 引用 被引量：5
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作者 Cheng Li HuaJianYao +4 位作者 Song Luo HaiJiang Zhang LingLi Li XiaoLi Wang ShengJun Ni 《Earth and Planetary Physics》 EI CSCD 2025年第2期253-265,共13页
The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structur... The Tan-Lu Fault Zone is a large NNE-trending fault zone that has a substantial effect on the development of eastern China and its earthquake disaster prevention efforts. Aiming at the azimuthally anisotropic structure in the upper crust and seismogenic tectonics in the Hefei segment of this fault, we collected phase velocity dispersion data of fundamental mode Rayleigh waves from ambient noise cross-correlation functions of ~400 temporal seismographs in an area of approximately 80 × 70 km along the fault zone. The period band of the dispersion data was ~0.5–10 s. We inverted for the upper crustal three-dimensional(3-D) shear velocity model with azimuthal anisotropy from the surface to 10 km depth by using a 3-D direct azimuthal anisotropy inversion method. The inversion result shows the spatial distribution characteristics of the tectonic units in the upper crust. Additionally, the deformation of the Tan-Lu Fault Zone and its conjugated fault systems could be inferred from the anisotropy model. In particular, the faults that have remained active from the early and middle Pleistocene control the anisotropic characteristics of the upper crustal structure in this area. The direction of fast axes near the fault zone area in the upper crust is consistent with the strike of the faults, whereas for the region far away from the fault zone, the direction of fast axes is consistent with the direction of the regional principal stress caused by plate movement. Combined with the azimuthal anisotropy models in the deep crust and uppermost mantle from the surface wave and Pn wave, the different anisotropic patterns caused by the Tan-Lu Fault Zone and its conjugated fault system nearby are shown in the upper and lower crust. Furthermore,by using the double-difference method, we relocated the Lujiang earthquake series, which contained 32 earthquakes with a depth shallower than 10 km. Both the Vs model and earthquake relocation results indicate that earthquakes mostly occurred in the vicinity of structural boundaries with fractured media, with high-level development of cracks and small-scale faults jammed between more rigid areas. 展开更多
关键词 ambient noise tomography azimuthal anisotropy upper crust seismogenic structure the Tan-Lu Fault Zone Hefei segment
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Enhancement of weathered crust elution-deposited rare earth ores leaching process with PQ-10 addition 认领 引用 被引量：1
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作者 Aoyang Sha Huifang Yang +4 位作者 Zhengyan He Zhigao Xu Chenjie Wu Ming Wu Ru'an Chi 《Journal of Rare Earths》 SCIE EI CAS CSCD 2025年第1期180-190,I0007,共11页
To solve the problems of the long development period,low mass transfer efficiency and high impurity conte nt in the in-situ leaching process of weathe red crust elution-deposited rare earth ores(WCE-DREO),cationic hyd... To solve the problems of the long development period,low mass transfer efficiency and high impurity conte nt in the in-situ leaching process of weathe red crust elution-deposited rare earth ores(WCE-DREO),cationic hydroxyethyl cellulose(PQ-10)was composited with conventional leaching agent ammonium sulfate((NH4)2SO4)to form a novel composite leaching agent.The effects of PQ-10 concentration,leaching temperature and leaching flow rate of the composite leaching agent on the leaching kinetics and mass transfer processes of rare earth(RE)and aluminum(Al)were investigated.Compared to the single leaching agent(NH4)2SO4,the composite leaching agent(2 wt%(NH4)2SO4+0.02 wt%PQ-10)can reduce the RE leaching equilibrium time from 465 to 130 min and increase the RE leaching efficiency and decrease the Al leaching efficiency.It also facilitates the leaching process of WCE-DREO by increasing the peak concentrations of RE and Al,reducing the theoretical tower plate height(HETP)and improving the leaching mass transfer efficiency.It is indicated that PQ-10 can promote the leaching of WCE-DREO.The leaching process of the composite leaching system conforms to the diffusion kinetic control model.When the PQ-10 concentration is in the range of 0.005 wt%-0.020 wt%,the reaction orders of RE and Al are 0.73 and 0.54,respectively,which shows a positive effect on the leaching velocity;when the PQ-10 concentration is in the range of 0.030 wt%-0.060 wt%,the reaction orders of RE and Al are-1.16 and-0.75,respectively,which show a negative effect on the leaching velocity.In the range of 10-50℃,the apparent activation energies of RE and Al are 15.02 and 17.31 kJ/mol,respectively,and the higher the leaching temperature,the smaller the HETP and the higher the leaching velocity and mass transfer efficiency.The increase in leaching flow rate contributes to the increase in the longitudinal diffusion velocity of the leaching agent within WCE-DREO,causing a shorter time for RE and Al to reach leaching equilibrium.In addition,the flow rate and HETP are consistent with the Van Deemter equation.At a flow rate of 0.8 mL/min,HETP was minimized and the optimal mass transfer efficiencies is achieved for RE and Al. 展开更多
关键词 Cationic hydroxyethyl cellulose Weathered crust elution-deposited rare earthores Leaching Novel compositeagent
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Exploration of playa surface crusts in Qehan Lake, China through field investigation and wind tunnel experiments 认领 引用 被引量：2
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作者 LIU Dongwei HAN Lijing +2 位作者 KOU Zihan GAO Xinyu WANG Jingjing 《Journal of Arid Land》 SCIE CSCD 2023年第5期491-507,共17页
Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial di... Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial distribution of playa surface crusts is important to recognize the manifestation of salt dust storms.The objective of this study was to explore the playa surface crust types as well as their spatial distribution and evolution of Qehan Lake in Inner Mongolia Autonomous Region,China to understand the salt dust release potential of different types of playa surface crusts.Various crust characteristics were investigated by field sampling in Qehan Lake,and playa surface crusts were further divided into five types:vegetated areas,salt crusts,clay flats,curly crusts,and margins.It should be noted that curly crusts were distributed in clay flats and covered only a small area in Qehan Lake.The spatial distribution characteristics of playa surface crust types were obtained by supervised classification of remote sensing images,and the salt dust release potential of crusts was explored by the wind tunnel experiments.The field investigation of Qehan Lake revealed that playa surface crust types had a circum-lake band distribution from the inside to the outside of this lake,which were successively vegetated areas,clay flats,salt crusts,and margins.The spatial distribution patterns of playa surface crust types were mainly controlled by the hydrodynamics of the playa,soil texture,and groundwater.There was a significant negative correlation between crust thickness and electrical conductivity.The results of the wind tunnel experiments showed that the initial threshold of friction wind velocity for the salt dust release was higher in clay flats(0.7–0.8 m/s)than in salt crusts(0.5–0.6 m/s).Moreover,the particle leap impact processes occurring under natural conditions may reduce this threshold value.Salinity was the main factor controlling the difference in the initial threshold of friction wind velocity for the salt dust release of clay flats and salt crusts.This study provides a scientific reference for understanding how salt dust is released from a lakebed,which may be used for ecological restoration of dry salt lakes. 展开更多
关键词 playa surface crust curly crusts salt crusts salt dust release wind tunnel experiments Qehan Lake
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Paleogeographic significance of unknown hyperextended continental crust in South Atlantic conjugated margin 认领 引用
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作者 C.D.Teixeira T.J.Girelli +5 位作者 H.Serratt H.O.S.Oliveira M.F.Cruz B.Conti P.Rodriguez F.Chemale Jr 《Geoscience Frontiers》 SCIE CAS CSCD 2025年第1期37-46,共10页
The paleogeographic reconstruction of fragmented and dispersed continents often poses a challenge due to the lack of information regarding the nature of that extend beneath passive margin basins.To define the width of... The paleogeographic reconstruction of fragmented and dispersed continents often poses a challenge due to the lack of information regarding the nature of that extend beneath passive margin basins.To define the width of the continental crust beneath passive margin basins and its implications for paleogeographic reconstruction of conjugate continental margins,this study investigates the architecture of the stretched continental crust of the southern South Atlantic conjugate margin.The investigated region encompasses South Africa,Namibia,southern Brazil,and Uruguay,which were formed during the Mesozoic rifting of SW Gondwana.Employing a multi-tool approach combining seismic interpretation,gravity,magnetometry,and U-Pb isotopic data,the research aims to quantify the extension of stretched continental crust and its implications for plate reconstructions.The study reveals that the restored stretched crust spans at least 150 km,emphasizing the significance of considering connections between both margins for realistic paleogeographic reconstructions.Furthermore,the distinct U-Pb zircon age distribution patterns between SW Africa and SE South America reinforce the lack of direct connections despite their Gondwanan origin.The missing link estimated in this study is around 150 km,comparable in size to major mountain ranges such as the Andean or Urals.This work sheds light on critical aspects of Earth’s dynamic crustal evolution and emphasizes the need for comprehensive reconstructions considering stretched and eroded crust in the South Atlantic conjugate margin. 展开更多
关键词 Hyperextended continental crust Reconstruction South Atlantic Ocean Passive margin Gondwana
Swelling inhibition and percolation promotion of PQ-10 on weathered crust elution-deposited rare earth ores 认领 引用
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作者 Aoyang Sha Huifang Yang +6 位作者 Meiling Jiang Zhengyan He Zhenhu Liu Zhigao Xu Yaguang Du Ming Wu Ru'an Chi 《Journal of Rare Earths》 SCIE EI CAS CSCD 2025年第7期1559-1570,共12页
Weathered crust elution-deposited rare earth ores(WREOs)are rich in medium and heavy rare earth.In order to improve the in-situ leaching process,which is prone to landslides and poor permeability,cationic hydroxyethyl... Weathered crust elution-deposited rare earth ores(WREOs)are rich in medium and heavy rare earth.In order to improve the in-situ leaching process,which is prone to landslides and poor permeability,cationic hydroxyethyl cellulose(PQ-10)was used as a novel green swelling inhibitor and percolation promoter and was mixed with conventional leaching agent ammonium sulfate((NH4)2SO4)to form a composite leaching agent to study the performance and mechanism of swelling inhibition and percolation promotion.Adding PQ-10 can inhibit the hydration swelling of WREOs,promote the percolation effect of the leaching agent,improve the rare earth(RE)leaching efficiency,and reduce the im purity aluminum(Al)leaching efficiency.Compared with the conventional leaching agent 2 wt%(NH4)2SO4,the percolation time is reduced by 50%by using the composite leaching agent(0.02 wt%PQ-10+2 wt%(NH4)2SO4).PQ-10 has positively charged quaternary ammonium groups and hydrophilic group hydroxyl groups,which makes it easy to adsorb on WREOs multiple sites through electrostatic interaction and hydrogen bonding,weakening the electrostatic repulsion between mineral particles,reducing the WREOs interlayer spacing,compressing the double electric layer thickness at the solid-liquid interface,weakening the mineral hydration swelling and increasing the percolation rate.The long carbon chains of the polymer entangle and link the fine mineral particles to agglomerate them,increasing their particle size and reduc ing their hydration dispersion,and preventing blockage of the pe rcolation pores caused by migration of the fine particles through the ore body with the solution.PQ-10 molecules also insert the mine ral interlayer and expulsion of the internal water,further inhibiting the swelling of WREOs.Adding PQ-10 reduces the surface tension of(NH4)2SO4solution,improving the spreading and spreading ability of the solution,reducing the adhesion work between molecules in the solid-liquid phase and the adhesion work reduction factor.It proves that PQ-10 promotes the percolation effect of the leaching process of WREOs.In addition,PQ-10 expands the leaching pore size and seepage channels,further improving the percolation rate. 展开更多
关键词 Weathered crust elution-deposited rare earth ores Swelling inhibition Percolation promotion Rare earth leaching Composite leaching agent
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Topographic differentiations of biological soil crusts and hydraulic properties in fixed sand dunes, Tengger Desert 认领 引用 被引量：16
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作者 Zhi Shan ZHANG Yong Le CHEN +3 位作者 Bin Xing XU Lei HUANG Hui Juan TAN Xue Jun DONG 《Journal of Arid Land》 SCIE CSCD 2015年第2期205-215,共11页
Biological soil crusts （BSCs） play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is... Biological soil crusts （BSCs） play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is unnown whether improved infiltration in moss BSCs is accompanied by an increase in soil hydraulic conductivity or water retention capacity. We investigated this question in the Tengger Desert, where a 43-year-old revegetation program has promoted the formation of two distinct types of BSCs along topographic positions, i.e. the moss-dominated BSCs on the interdune land and windward slopes of the fixed sand dunes, and the al- gal-dominated BSCs on the crest and leeward slopes. Soil water retention capacity and hydraulic conductivity were measured using an indoor evaporation method and a field infiltration method. And the results were fitted to the van Genuchten-Mualem model. Unsaturated hydraulic conductivities under greater water pressure （〈-0.01 MPa） and water retention capacities in the entire pressure head range were higher for both crust types than for bare sand. However, saturated and unsaturated hydraulic conductivities in the near-saturation range （〉-0.01 MPa） showed decreasing trends from bare sand to moss crusts and to algal crusts. Our data suggested that topographic differentiation of BSCs significantly affected not only soil water retention and hydraulic conductivities, but also the overall hydrology of the fixed sand dunes at a landscape scale, as seen in the reduction and spatial variability in deep soil water storage. 展开更多
关键词 algal crusts hydraulic conductivity moss crusts soil water retention curve Tengger Desert
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Development of Soil Crusts Under Simulated Rainfall and Crust Formation on a Loess Soil as Influenced by Polyacrylamide 认领 引用 被引量：13
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作者 HU Xia LIU Lian-You +3 位作者 LI Shun-Jiang CAI Qiang-Guo LU Yan-Li GUO Jin-Rui 《Pedosphere》 SCIE CAS CSCD 2012年第3期415-424,共10页
This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and iden-tified the relationships between soil crust and splash erosion under simulated rainfall.The effect... This study evaluated the morphological characteristics and dynamic variation in characteristics of soil crust and iden-tified the relationships between soil crust and splash erosion under simulated rainfall.The effect of polyacrylamide (PAM) on soil aggregate stabilization and crust formation was also investigated.A laboratory rainfall simulation experiment was carried out using soil sample slices.The slices were examined under a polarized light microscopy and a scanning electron microscope (SEM).The results revealed that the soil crusts were thin and were characterized by a greater density,higher shear strength,finer porosity,and lower saturated hydraulic conductivity than the underlying soil.Two types of crusts,i.e.,structural and depositional crusts,were observed.Soil texture was determined to be the most important soil variable influ-encing surface crust formation;depositional crust formation was primarily related to the skeleton characteristics of the soil and happened when the soil contained a high level of medium and large aggregates.The crust formation processes observed were as follows:1) The fine particles on the soil surface became spattered,leached,and then rough in response to raindrop impact and 2) the fine particles were washed into the subsoil pores while a compact dense layer concurrently formed at soil surface due to the continual compaction by the raindrops.Therefore,the factors that influenced structural crust formation were a large amount of fine particles in the soil surface,continual impact of raindrops,dispersion of aggregates into fine particles,and the formation of a compact dense layer concurrently at the soil surface.It was concluded that the most important factor in the formation of soil crusts was raindrop impact.When polyacrylamide (PAM) was applied,it restored the soil structure and greatly increased soil aggregate stabilization.This effectively prevented crust formation.However,this function of PAM was not continuously effective and the crust reformed with long-term rainfall.In conclusion,this study showed that soil micromorphological studies were a useful method for evaluating soil crust formation. 展开更多
关键词 depositional crust raindrop impact soil aggregates splash erosion structural crust
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Rates of generation and growth of the continental crust 认领 引用 被引量：27
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作者 Chris Hawkesworth Peter A.Cawood Bruno Dhuime 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第1期165-173,共9页
Models for when and how the continental crust was formed are constrained by estimates in the rates o crustal growth. The record of events preserved in the continental crust is heterogeneous in time with distinctive pe... Models for when and how the continental crust was formed are constrained by estimates in the rates o crustal growth. The record of events preserved in the continental crust is heterogeneous in time with distinctive peaks and troughs of ages for igneous crystallisation, metamorphism, continental margin and mineralisation. For the most part these are global signatures, and the peaks of ages tend to b associated with periods of increased reworking of pre-existing crust, reflected in the Hf isotope ratios o zircons and their elevated oxygen isotope ratios. Increased crustal reworking is attributed to periods o crustal thickening associated with compressional tectonics and the development of supercontinents Magma types similar to those from recent within-plate and subduction related settings appear to hav been generated in different areas at broadly similar times before ~3.0 Ga. It can be difficult to put th results of such detailed case studies into a more global context, but one approach is to consider when plate tectonics became the dominant mechanism involved in the generation of juvenile continental crust The development of crustal growth models for the continental crust are discussed, and a number o models based on different data sets indicate that 65%-70% of the present volume of the continental crus was generated by 3 Ga. Such estimates may represent minimum values, but since ~3 Ga there has been reduction in the rates of growth of the continental crust. This reduction is linked to an increase in th rates at which continental crust is recycled back into the mantle, and not to a reduction in the rates a which continental crust was generated. Plate tectonics results in both the generation of new crust and it destruction along destructive plate margins. Thus, the reduction in the rate of continental crustal growth at ~3 Ga is taken to reflect the period in which plate tectonics became the dominant mechanism b which new continental crust was generated. 展开更多
关键词 Continental crust growth curves Rates of crustal growth Tectonics
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Generation and preservation of continental crust in the Grenville Orogeny 认领 引用 被引量：12
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作者 Christopher J.Spencer Peter A.Cawood +5 位作者 Chris J.Hawkesworth Anthony R.Prave Nick M.W.Roberts Matthew S.A.Horstwood Martin J.Whitehouse EIMF 《Geoscience Frontiers》 SCIE CAS CSCD 2015年第3期357-372,共16页
Detrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of'peaks'and'troughs'.The peaks are interpreted to represent either period... Detrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of'peaks'and'troughs'.The peaks are interpreted to represent either periods of enhanced generation of granitic magma perhaps associated with mantle overturn and superplume events,or preferential preservation of continental crust during global collisional orogenesis.The close association of those peaks with the assembly of supercontinents implies a causal relationship between collisional orogenesis and the presence of zircon age peaks.Here these two end-member models(episodic periodicity of increased magmatism versus selective preservation during collisional orogenesis)are assessed using U-Pb,Hf,and 0 analysis of detrital zircons from sedimentary successions deposited during the-1.3-1.1 Ga accretionary,-1.1-0.9 Ga collisional,and〈0.9 Ga extensional collapse phases of the Grenville orogenic cycle in Labrador and Scotland.The pre-collisional,accretionary stage provides a baseline of continental crust present prior to orogenesis and is dominated by Archean and Paleoproterozoic age peaks associated with pre-1300 Ma Laurentian geology.Strata deposited during the Grenville Orogeny display similar Archean and Paleoproterozoic detrital populations along with a series of broad muted peaks from-1500 to 1100 Ma.However,post-collisional sedimentary successions display a dominant age peak between 1085 and 985 Ma,similar to that observed in modern North American river sediments.Zircons within the post-orogenic sedimentary successions have progressively lower EHf and higher-lSO values from-1800 to-1200 Ma whereupon they have higher EHf and-3180 within the dominant 1085-985 Ma age peak.Furthermore,the Lu-Hf isotopic profile of the Grenville-related age peak is consistent with significant assimilation and contamination by older crustal material,The timing of this dominant age peak coincides with the peak of metamorphism and magmatism associated with the Grenville Orogeny,which is a typical collisional orogenic belt.The change from broad muted age peaks in the syn-orogenic strata to a single peak in the post-orogenic sedimentary successions and in the modern river sediments implies a significant shift in provenance following continental collision.This temporal change in provenance highlights that the source(s),from which detrital zircons within syn-orogenic strata were derived,was no longer available during the later stages of the accretionary and collisional stages of the orogenic cycle.This may reflect some combination of tectonic burial,erosion,or possibly recycling into the mantle by tectonic erosion of the source(s).During continental collision,the incorporated continental crust is isolated from crustal recycling processes operative at subduction margins.This tectonic isolation combined with sedimentary recycling likely controls the presence of the isotopic signature associated with the Grenville Orogeny in the modern Mississippi and Appalachian river sed-iments.These results imply that zircon age peaks,which developed in conjunction with supercontinents,are the product of selective crustal preservation resulting from collisional orogenesis. 展开更多
关键词 Zircon Continental crust Grenville Orogeny Crustal preservation
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