Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study emplo...Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study employs shortwave infrared(SWIR) spectral scalars for alteration mineral mapping and three-dimensional modeling of the Ulan Uzhur Ag polymetallic deposit, a newly discovered epithermal deposit in the Qimantagh. Alteration zoning transitions from illitemuscovite-carbonate-pyrite in the core(Zone Ⅰ), through muscovite ± illite-kaolinite-chlorite-carbonate(Zone Ⅱ), to muscovite-chlorite-biotite(Zone Ⅲ) at the periphery. The Zone Ⅰ with mineralization features long-wavelength white mica(wAlOH > 2207 nm) with a high Illite Crystallinity(IC)(mean > 2.0), suggesting a relatively high-temperature environment conducive to mineralization. Petrographic analyses with fluid inclusion and IC curve characteristics suggests that fluid boiling may be a pivotal mechanism for mineral precipitation. Furthermore, surface mapping and deep threedimensional modeling of spectral characteristics reveal a correlation between long-wavelength white mica, high IC and mineralization zones. These findings indicate that SWIR spectroscopy reveal the evolution of fluids and provide valuable guidance for future exploration efforts.展开更多
To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.T...To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.展开更多
The Chinese Altai,a key component of the Central Asian Orogenic Belt(CAOB),represents a significant Phanerozoic accretionary orogenic belt.The oceanic-continental subduction processes spanning the Cambrian to Carbonif...The Chinese Altai,a key component of the Central Asian Orogenic Belt(CAOB),represents a significant Phanerozoic accretionary orogenic belt.The oceanic-continental subduction processes spanning the Cambrian to Carboniferous and subsequent intracontinental extension since the Triassic have been well documented in the Chinese Altai,the southwestern segment of the CAOB.Deciphering the petrogenetic evolution of this region during the Permian is thus crucial for advancing our understanding of its tectonic transitions.However,the Permian tectonic setting of the Chinese Altai remains contentious.To address this knowledge gap,this study presents new geochronological and geochemical data for the Jiangjunshan pluton in the southern Chinese Altai.Zircon U-Pb geochronology reveals that the gabbro and two-mica alkali feldspar granite—which collectively constitute the primary lithology of the Jiangjunshan pluton—were emplaced at∼272±3.5 and∼272±1.6 Ma,respectively.Geochemically,the gabbro exhibits pronounced light rare-earth element(LREE)depletion,low Nb/Yb(0.39–0.46)and Ti/V(23.7–25.3)ratios,and trace-element signatures akin to normal mid-ocean ridge basalts(N-MORB).However,its conspicuous Nb-Ta depletion parallels that of island arc basalts.Depleted Hf-Nd isotopic compositions(ε_(Hf)(t)=+0.60 to+4.63,ε_(Nd)(t)=+6.32 to+7.80)in the gabbro,coupled with negligible correlation betweenε_(Nd)(t)and SiO2 contents imply limited crustal assimilation during magma evolution.Petrological modeling,based on Sm/Yb and La concentrations,suggests the gabbroic melt derived from∼8%–20%spinel lherzolte mantle melting.Analogously depleted Hf-Nd isotopes(ε_(Hf)(t)=+6.81 to+9.10,ε_(Nd)(t)=+0.79 to+1.45)in the granite,together with petrographic evidence lacking mafic-ultramafic xenoliths,point to a juvenile lower-crustal source.Integrating the gabbro’s N-MORB-like affinity with arc-specific features,regional ultrahigh-temperature metamorphism in southern Chinese Altai,and Permian tectonics,we propose a ridge-subduction regime as the likely petrogenetic setting for the Jiangjunshan magmas.During ridge subduction,upwelling of asthenospheric mantle beneath the ridge induced partial melting of the lithospheric mantle,giving rise to the parental magma of the Jiangjunshan gabbro.This mafic magma underplating subsequently heated the juvenile lower crust,triggering its partial melting and generating the parental magma of the two-mica alkali feldspar granite.Our model indicates that ridge-subduction-related magmatism persisted in the Chinese Altai until the Middle Permian,followed by a tectonic shift from oceanic-continental subduction to intracontinental extension.展开更多
Seismic fault rupture can extend to the surface,and the resulting surface deformation can cause severe damage to civil engineering structures crossing the fault zones.Coseismic Surface Rupture Prediction Models(CSRPMs...Seismic fault rupture can extend to the surface,and the resulting surface deformation can cause severe damage to civil engineering structures crossing the fault zones.Coseismic Surface Rupture Prediction Models(CSRPMs)play a crucial role in the structural design of fault-crossing engineering and in the hazard analysis of fault-intensive areas.In this study,a new global coseismic surface rupture database was constructed by compiling 171 earthquake events(Mw:5.5-7.9)that caused surface rupture.In contrast to the fault classification in traditional empirical relationships,this study categorizes earthquake events as strike-slip,dip-slip,and oblique-slip.CSRPMs utilizing Bayesian ridge regression(BRR)were developed to estimate parameters such as surface rupture length,average displacement,and maximum displacement.Based on Bayesian theory,BRR combines the benefits of both ridge regression and Bayesian linear regression.This approach effectively addresses the issue of overfitting while ensuring the strong model robustness.The reliability of the CSRPMs was validated by residual analysis and comparison with post-earthquake observations from the 2023 Türkiye earthquake doublet.The BRR-CSRPMs with new fault classification criteria are more suitable for the probabilistic hazard analysis of complex fault systems and dislocation design of fault-crossing engineering.展开更多
The Ninety-East Ridge(NER)is located in the semioceanic to oceanic region of the southern Bengal Fan in the Northeast Indian Ocean.The sedimentary environment,ocean currents,and scientific issues related to climate ch...The Ninety-East Ridge(NER)is located in the semioceanic to oceanic region of the southern Bengal Fan in the Northeast Indian Ocean.The sedimentary environment,ocean currents,and scientific issues related to climate change have always been the focus of scientists.To well understand the sedimentary environment of the sea area,we studied the modern sedimentary environment of the NER by analyzing the redox-sensitive trace elements(RSEs)and biomarkers in the surface sediments of the northern region and both sides of the NER and the mechanism of their formation.The ratios of Mo/U(average 2.22),(Cu+Mo)/Zn(average 1.51),and the results ofδCe<1 of the sediment samples,all indicate the reduction of the sedimentary environment.In addition,the ratio of pristane(Pr)to phytane(Ph),C30diahopane to C30 hopane,and diasterane to sterane were low in all samples,on average of 1.03,0.9,and 0.33,respectively.The analysis of RSE and biomarker data revealed that the sedimentary environment on seabed of the NER is generally a rare low-oxygen reduction environment.Through the analysis of sediment characteristics,material sources,and ocean currents,we preliminarily constructed a genetic model for the low-oxygen reducing environment of surface sediments in the NER.We believe that the low-oxygen reduction environment of surface sediment in the NER could be influenced by multiple factors,such as terrestrial input of materials,productivity at sea surface,and sediment particle size.展开更多
The hydrothermal signatures of mid-ocean ridge sediments are crucial geochemical data providing insights into investigating hydrothermal anomalies and locating seafloor massive sulfide deposits.This paper outlines the...The hydrothermal signatures of mid-ocean ridge sediments are crucial geochemical data providing insights into investigating hydrothermal anomalies and locating seafloor massive sulfide deposits.This paper outlines the geochemical features of 24 surface sediments and one sediment core(26 V-GC 01,294 cm)along the South Mid-Atlantic Ridge(SMAR)from 18°S to 22°S,an area where hydrothermal active fields have yet to be discovered.The surface sediments mainly consist of biogenic carbonates,aluminosilicates,and hydrothermal Fe-Mn(oxy)oxides.The core sediments primarily comprise organic matter,detrital materials,hydrothermal components,and substances scavenged from seawater.The rare Earth element(REE)patterns suggest the presence of hydrothermal contributions within the surface and core sediments.The enrichment factors for Fe,Mn,Cu,and Zn in surface sediments suggest these metals are concentrated at the 19°S,21°S,and 21.5°S segments,further indicating their potential as hydrothermal active fields.Downcore variations of Fe,Mn,P,Cu,Pb,V,and Co suggest at least six episodes of hydrothermal activity.The impact of hydrothermal processes on the sediments from SMAR 18°S to 22°S indicates that the study area has the potential to host a significant number of hydrothermal active fields.展开更多
A coupled tide-surge-wave model was established to analyze the impacts of radial sand ridges on storm surges in the South Yellow Sea.Numerical topography experiments were designed on the basis of multiple well-verifie...A coupled tide-surge-wave model was established to analyze the impacts of radial sand ridges on storm surges in the South Yellow Sea.Numerical topography experiments were designed on the basis of multiple well-verified types of extreme weather events.The findings demonstrated that the radial sand ridges(RSRs)generally enhanced tidal levels,current velocities,and significant wave heights in the affected area.The nonlinear effects of shallow water in the radial sand ridge area can induce large tide ranges.A unique seabed can cause an increase in current speed from the open sea to the nearshore.Another impact is that subaqueous ridges can result in shallow water conditions,and the degree of depth-induced wave breaking significantly varies.Compared with those in the northern and southern radial sand ridge areas,the tidal levels,current speeds,and wave heights in the middle radial sand ridge area were the highest,which can cause more severe storm surge disasters.Additionally,the wave radiation stress varied obviously under the action of fan-shaped sand ridges.Thus,it is necessary to consider wave-current interactions when modeling storm surges in sand ridges.展开更多
基金supported by the Natural Science Foundation of China(Grant No.42372346,41802080,42030809,41873043).
文摘Epithermal deposits are characterized by complex low-temperature hydrothermal alterations, but the links between mineralization and superimposed alteration are obscure and require further elucidation. This study employs shortwave infrared(SWIR) spectral scalars for alteration mineral mapping and three-dimensional modeling of the Ulan Uzhur Ag polymetallic deposit, a newly discovered epithermal deposit in the Qimantagh. Alteration zoning transitions from illitemuscovite-carbonate-pyrite in the core(Zone Ⅰ), through muscovite ± illite-kaolinite-chlorite-carbonate(Zone Ⅱ), to muscovite-chlorite-biotite(Zone Ⅲ) at the periphery. The Zone Ⅰ with mineralization features long-wavelength white mica(wAlOH > 2207 nm) with a high Illite Crystallinity(IC)(mean > 2.0), suggesting a relatively high-temperature environment conducive to mineralization. Petrographic analyses with fluid inclusion and IC curve characteristics suggests that fluid boiling may be a pivotal mechanism for mineral precipitation. Furthermore, surface mapping and deep threedimensional modeling of spectral characteristics reveal a correlation between long-wavelength white mica, high IC and mineralization zones. These findings indicate that SWIR spectroscopy reveal the evolution of fluids and provide valuable guidance for future exploration efforts.
基金supported by the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2024ZD0302502 for WZ)the National Natural Science Foundation of China(Grant No.92365210 for WZ)+1 种基金Tsinghua Initiative Scientific Research Program (for WZ)the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies (JIAOT,for YH)。
文摘To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.
基金supported by the Xinjiang Key R&D Program(No.2022B03015-3)the National Natural Science Foundation of China(No.91962214)+1 种基金the Fundamental Research Funds for the Central Universities,Chang’an University(No.300102272201)the“Tianchi Talent”Plan to Chang-Zhi Wu.
文摘The Chinese Altai,a key component of the Central Asian Orogenic Belt(CAOB),represents a significant Phanerozoic accretionary orogenic belt.The oceanic-continental subduction processes spanning the Cambrian to Carboniferous and subsequent intracontinental extension since the Triassic have been well documented in the Chinese Altai,the southwestern segment of the CAOB.Deciphering the petrogenetic evolution of this region during the Permian is thus crucial for advancing our understanding of its tectonic transitions.However,the Permian tectonic setting of the Chinese Altai remains contentious.To address this knowledge gap,this study presents new geochronological and geochemical data for the Jiangjunshan pluton in the southern Chinese Altai.Zircon U-Pb geochronology reveals that the gabbro and two-mica alkali feldspar granite—which collectively constitute the primary lithology of the Jiangjunshan pluton—were emplaced at∼272±3.5 and∼272±1.6 Ma,respectively.Geochemically,the gabbro exhibits pronounced light rare-earth element(LREE)depletion,low Nb/Yb(0.39–0.46)and Ti/V(23.7–25.3)ratios,and trace-element signatures akin to normal mid-ocean ridge basalts(N-MORB).However,its conspicuous Nb-Ta depletion parallels that of island arc basalts.Depleted Hf-Nd isotopic compositions(ε_(Hf)(t)=+0.60 to+4.63,ε_(Nd)(t)=+6.32 to+7.80)in the gabbro,coupled with negligible correlation betweenε_(Nd)(t)and SiO2 contents imply limited crustal assimilation during magma evolution.Petrological modeling,based on Sm/Yb and La concentrations,suggests the gabbroic melt derived from∼8%–20%spinel lherzolte mantle melting.Analogously depleted Hf-Nd isotopes(ε_(Hf)(t)=+6.81 to+9.10,ε_(Nd)(t)=+0.79 to+1.45)in the granite,together with petrographic evidence lacking mafic-ultramafic xenoliths,point to a juvenile lower-crustal source.Integrating the gabbro’s N-MORB-like affinity with arc-specific features,regional ultrahigh-temperature metamorphism in southern Chinese Altai,and Permian tectonics,we propose a ridge-subduction regime as the likely petrogenetic setting for the Jiangjunshan magmas.During ridge subduction,upwelling of asthenospheric mantle beneath the ridge induced partial melting of the lithospheric mantle,giving rise to the parental magma of the Jiangjunshan gabbro.This mafic magma underplating subsequently heated the juvenile lower crust,triggering its partial melting and generating the parental magma of the two-mica alkali feldspar granite.Our model indicates that ridge-subduction-related magmatism persisted in the Chinese Altai until the Middle Permian,followed by a tectonic shift from oceanic-continental subduction to intracontinental extension.
基金Foundation of China under Grant Nos. U2139207 and 52378517the Natural Science Foundation of Hubei Province under Grant No. 2023AFB934
文摘Seismic fault rupture can extend to the surface,and the resulting surface deformation can cause severe damage to civil engineering structures crossing the fault zones.Coseismic Surface Rupture Prediction Models(CSRPMs)play a crucial role in the structural design of fault-crossing engineering and in the hazard analysis of fault-intensive areas.In this study,a new global coseismic surface rupture database was constructed by compiling 171 earthquake events(Mw:5.5-7.9)that caused surface rupture.In contrast to the fault classification in traditional empirical relationships,this study categorizes earthquake events as strike-slip,dip-slip,and oblique-slip.CSRPMs utilizing Bayesian ridge regression(BRR)were developed to estimate parameters such as surface rupture length,average displacement,and maximum displacement.Based on Bayesian theory,BRR combines the benefits of both ridge regression and Bayesian linear regression.This approach effectively addresses the issue of overfitting while ensuring the strong model robustness.The reliability of the CSRPMs was validated by residual analysis and comparison with post-earthquake observations from the 2023 Türkiye earthquake doublet.The BRR-CSRPMs with new fault classification criteria are more suitable for the probabilistic hazard analysis of complex fault systems and dislocation design of fault-crossing engineering.
基金Supported by the Science and Technology Development Foundation of South China Sea Bureau,Ministry of Natural Resources,China(No.230204)the National Program on Global Change and Air-Sea Interaction(No.GASI-02-IND-CJ04)+1 种基金the Natural Science Foundation of Guangdong Province,China(No.2021A1515012589)the Key Technologies Research and Development Program of Guangzhou,Guangdong Province,China(No.2023B03J1379)。
文摘The Ninety-East Ridge(NER)is located in the semioceanic to oceanic region of the southern Bengal Fan in the Northeast Indian Ocean.The sedimentary environment,ocean currents,and scientific issues related to climate change have always been the focus of scientists.To well understand the sedimentary environment of the sea area,we studied the modern sedimentary environment of the NER by analyzing the redox-sensitive trace elements(RSEs)and biomarkers in the surface sediments of the northern region and both sides of the NER and the mechanism of their formation.The ratios of Mo/U(average 2.22),(Cu+Mo)/Zn(average 1.51),and the results ofδCe<1 of the sediment samples,all indicate the reduction of the sedimentary environment.In addition,the ratio of pristane(Pr)to phytane(Ph),C30diahopane to C30 hopane,and diasterane to sterane were low in all samples,on average of 1.03,0.9,and 0.33,respectively.The analysis of RSE and biomarker data revealed that the sedimentary environment on seabed of the NER is generally a rare low-oxygen reduction environment.Through the analysis of sediment characteristics,material sources,and ocean currents,we preliminarily constructed a genetic model for the low-oxygen reducing environment of surface sediments in the NER.We believe that the low-oxygen reduction environment of surface sediment in the NER could be influenced by multiple factors,such as terrestrial input of materials,productivity at sea surface,and sediment particle size.
基金Supported by the China Ocean Mineral Resources R&D Association(No.DY135-S2-2)the Basic Scientific Fund for National Public Research Institutes of China(No.2021Q01)the National Natural Science Foundation of China(Nos.42106080,42006180,42276080)。
文摘The hydrothermal signatures of mid-ocean ridge sediments are crucial geochemical data providing insights into investigating hydrothermal anomalies and locating seafloor massive sulfide deposits.This paper outlines the geochemical features of 24 surface sediments and one sediment core(26 V-GC 01,294 cm)along the South Mid-Atlantic Ridge(SMAR)from 18°S to 22°S,an area where hydrothermal active fields have yet to be discovered.The surface sediments mainly consist of biogenic carbonates,aluminosilicates,and hydrothermal Fe-Mn(oxy)oxides.The core sediments primarily comprise organic matter,detrital materials,hydrothermal components,and substances scavenged from seawater.The rare Earth element(REE)patterns suggest the presence of hydrothermal contributions within the surface and core sediments.The enrichment factors for Fe,Mn,Cu,and Zn in surface sediments suggest these metals are concentrated at the 19°S,21°S,and 21.5°S segments,further indicating their potential as hydrothermal active fields.Downcore variations of Fe,Mn,P,Cu,Pb,V,and Co suggest at least six episodes of hydrothermal activity.The impact of hydrothermal processes on the sediments from SMAR 18°S to 22°S indicates that the study area has the potential to host a significant number of hydrothermal active fields.
基金financially supported by the Fundamental Research Funds for the Central Universities(Grant No.B210202031)the National Natural Science Foundation of China(Grant No.41606042)。
文摘A coupled tide-surge-wave model was established to analyze the impacts of radial sand ridges on storm surges in the South Yellow Sea.Numerical topography experiments were designed on the basis of multiple well-verified types of extreme weather events.The findings demonstrated that the radial sand ridges(RSRs)generally enhanced tidal levels,current velocities,and significant wave heights in the affected area.The nonlinear effects of shallow water in the radial sand ridge area can induce large tide ranges.A unique seabed can cause an increase in current speed from the open sea to the nearshore.Another impact is that subaqueous ridges can result in shallow water conditions,and the degree of depth-induced wave breaking significantly varies.Compared with those in the northern and southern radial sand ridge areas,the tidal levels,current speeds,and wave heights in the middle radial sand ridge area were the highest,which can cause more severe storm surge disasters.Additionally,the wave radiation stress varied obviously under the action of fan-shaped sand ridges.Thus,it is necessary to consider wave-current interactions when modeling storm surges in sand ridges.
