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Molecular dynamics simulation of quartz deformation under slow earthquake background

Science China earth sciences 2025年第2期68卷 598-610页

作者： Jingxian SUN Qianqian GUO Quanlin HOU college of earth and Planetary sciences University of Chinese Academy of SciencesKey Laboratory of Computational GeodynamicsCASBeijing 100049China

Slow earthquakes are the primary mechanism of slow energy release,and research on the focal mechanism has been *** have primarily focused on the friction law based on physical mechanisms and have suggested that slow earthquakes are caused by brittle ***,the focal strength and structural characteristics of slow earthquakes in subduction zones provide evidence of plastic *** is the role of plastic deformation in the focal mechanisms of slow earthquakes?Mechanochemical study have shown that mechanical forces can directly affect chemical *** this study,we examine the storage and release of chemical energy during plastic deformation and consider a mechanochemical process in the focal mechanism of slow *** with the Tersoff potential,molecular dynamics simulation on the shear deformation process of twoα-quartz crystals show that the shear modulus ofα-quartz is 18 GPa,and that the crystal model primarily exhibits atoms flowing and changing in the direction of chemical bonds during the steady-state flow *** molecular potential energy and stress vary in an oscillating up-and-down curve during shear,indicating that chemical energy can be stored and released during plastic *** is consistent with the energy variation during slow *** the initial simple-shear loading condition,α-quartz crystals undergo general shear deformation instead of plane strain and the angle between the longest instantaneous stretching axis(ISA_(1))and the shearing direction is approximately 30°,not 45°.Both the deformation type and direction of ISA_(1)are contrary to basic deformation theory,which may provide clues for future *** study reveals the process of quartz elastic-plastic shear deformation on an atomic *** information is useful for understanding focal mechanisms of slow *** study is part of a series of investigations on tectonic stress chemistry.

关键词： Slow earthquake α-quartz Plastic strain energy Tectonic stress chemistry Tersoff potential

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Solar cycles during the seventeenth century revealed by equatorial aurora records

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earth and Planetary Physics 2025年第1期9卷 182-187页

作者： Yong Wei LiMei Yan Key Laboratory of earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China college of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on earth,while also deepening our knowledge of stellar physics and solar system *** the solar cycles between 1600 and 1700-especially the post-1645 Maunder Minimum,characterized by significantly reduced solar activity-poses challenges to existing solar activity *** study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to ***,a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles,diverging from the widely accepted record of 12 cycles during that *** research enhances our understanding of historical solar activity,and underscores the importance of integrating diverse historical sources into modern analyses.

关键词： solar cycle Maunder Minimum solar activity red equatorial aurora West Pacific geomagnetic anomaly

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Geochemistry of Neoproterozoic metavolcanic rocks from the Tahtai Logomiti area,Tigrai,Northern Ethiopia:Implication for petrogenesis and tectonic settings

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Acta Geochimica 2025年第1期44卷 128-144页

作者： Azeb Gebremicale Mulugeta Alene Teklay Gidey School of earth sciences Mekelle UniversityP.O.Box:231MekelleEthiopia School of earth sciences Addis Ababa UniversityP.O.Box:1176Addis AbabaEthiopia Department of earth Environmental and Planetary SciencesCase Western Reserve UniversityClevelandOHUSA Faculty of mines Aksum UniversityP.O.Box:1010AksumEthiopia

The Tahtai Logomiti area is characterized by metavolcanic and metavolcaniclastic interbedded with clastic and carbonate metasedimentary rocks of Neoproterozoic *** geological,petrographic,major,and trace elements data were used to evaluate the metamorphism,petrogenesis,and paleo-tectonic setting of the *** field and petrographic observation indicate that the area has undergone greenschist facies *** on mineralogy and geochemical attributes,these metavolcanic rocks are classified as basalt,basaltic-andesite,andesite,and *** moderate degrees of light rare earth element(LREE)enrichment,flat heavy rare earth element(HREE)pattern,and low Nb/Y ratio,represent shallow mantle *** addition to that,the TiO_(2)/Yb ***/Yb diagram,high(La/Yb)N ratio(>3.44),indicates shallow melting and depleted magma ***,the high ratios of(Th/Ta)>3.8,(La/Ta)>38,and low ratios of(Th/La)<1,(Nb/La)<1,and high Pb content would indicate crustal contamination of the *** discrimination diagram and trace element ratios(Nb/Y,La/Sc,La/Y,and La/Th)indicate that the metavolcanic rocks have a calc-alkaline *** addition,the ZrNb-Y and Th-Hf-Ta plots show that the rocks formed under a volcanic-arc *** general petrological and geochemical characteristics of the Tahtai Logomiti metavolcanic rocks suggest that the area is associated with subduction-related arc accretion of the Arabian Nubian Shield.

关键词： Deformation Metamorphism Foliation Calc-alkaline Neoproterozoic Arabian Nubian Shield

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Grounded-source short offset transient electromagnetic method:Theory and applications in deep mineral exploration

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Science China earth sciences 2025年第2期68卷 626-638页

作者： Guoqiang XUE Xin WU Weiying CHEN Nannan ZHOU Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China college of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded *** Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for ***,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource *** study explores the theoretical framework,instrumentation,data processing,and field applications of *** on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source ***-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's *** of SOTEM to the deep exploration of the Zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km *** results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.

关键词： Far-source observation Plane wave model approximation Grounded-source short-offset transient electromagnetic method Wide-bandwidth exploration equipment Three-dimensional hybrid inversion

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Petrogenesis of rodingites along the northern margin of the North China Craton: Constraints from zirconology and whole-rock geochemistry

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Science China earth sciences 2025年第3期68卷 750-767页

作者： Jing RAN Hao WANG Jinhui YANG Yaoqi YAN Yusheng ZHU Baoquan ZHOU State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and Geophysics Chinese Academy of Sciences college of earth and Planetary sciences University of Chinese Academy of Sciences

Rodingite is a metasomatic product formed from various rock types by aqueous fluids, providing a direct record of lithosphere-hydrosphere interactions and serving as a key carrier of surface water into earth's deep interior（water content >1.5wt.%）. Determining the properties of metasomatic fluids is crucial for understanding the petrogenesis of rodingites. In this study,we conducted a detailed study of mineral inclusions, U-Pb ages, trace elements, and Hf-O isotopes of zircon, as well as wholerock geochemical and Sr-Nd-Hf isotopic data on rodingites and associated felsic alkaline veins/dikes along the northern margin of the North China Craton（NMNCC）, with aims to elucidate their formation ages, petrogenesis, and geodynamic settings. The results show that zircons from syenite and albite syenite veins/dikes exhibit clear oscillatory zoning, a wide range of Th/U ratios（0.0001–4.073）, low concentrations of rare-earth elements（REEs）, and low crystallization temperatures（<600°C）. These characteristics suggest that the zircons crystallized from fluids separated from late-stage melts during magma evolution. Consequently, the zircon U-Pb ages obtained through Secondary Ion Mass Spectrometry（SIMS） and Laser Ablation Inductively Coupled Plasma Mass Spectrometry（LA-ICPMS） analyses（389.1±3.5 to 390.2±1.6 Ma） record the timing of hydrothermal fluid activity. Zircons within the rodingites contain grandite, hematite, and aqueous fluid inclusions, indicating their formation during rodingitization, with an oxidizing, water-rich fluid acting as the metasomatic agent. SIMS and LA-ICPMS analyses of these zircons yielded U-Pb ages of 388.1±3.9 and 388.6±4.6 Ma, which register the formation ages of the rodingites. Both the syenite and albite syenite samples display high total alkali contents（9.9–13.9 wt.%）, consistent initial Sr isotopic ratios（0.7047–0.7051）,negative εNd（t）(-10.1 to-8.5) and εHf（t）(-13.9 to-13.7) values, and slightly elevated zircon δ18O values（6.20‰±0.18‰）compared to ma

关键词： North China Craton Rodingite Syenite Inclusions Zircon U-Pb age Sr-Nd-Hf-O isotopes

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The role of sub-continental lithosphere mantle in deep F and Cl cycling:Insight from the Dabeigou basalts,North China Craton

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Science China earth sciences 2025年第2期68卷 564-580页

作者： Yadong WU Jinhui YANG Jinfeng SUN Hao WANG Baoquan ZHOU State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China college of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Computational Geodynamics University of Chinese Academy of SciencesBeijing 100049China

The sub-continental lithosphere mantle(SCLM)represents a mechanical barrier that separate the convecting mantle from the exosphere,and possesses the ability to sequester and release volatiles,making it an integral part in deep volatile *** we explore the SCLM in modulating F and Cl cycling through a case study from the Early Cretaceous Dabeigou basalts in the North China Craton(NCC).These lavas are associated with decratonization of the NCC,a process involving significant removal and replacement of the ancient *** Dabeigou basalts,characterized by arc magma-like trace element signatures,evolved initial^(87)Sr/^(86)Sr(0.70574–0.70578),ε_(Nd)(t)(-11.2–-11.1),andε_(Hf)(t)(-13.7–-13.4)values,along with high Fe/Mn ratios,Ni contents,andδ^(18)O values(5.8‰–6.8‰)of olivine phenocrysts,are compatible with their origination from a veined,pyroxene-rich source formed through the infiltration and interaction of hydrous silicate melts from the subducting Pacific slabs with ambient ***-hosted melt inclusions of the Dabeigou basalts have compositions similar to the whole rocks,indicating that they record pre-eruptive melt compositions forming the whole *** melt inclusions exhibit high F(1371–2316 ppm)and moderate Cl(688–900 ppm)contents,with high F/Cl ratios of 2.1±0.3(1σ).The F and Cl signatures of the Dabeigou basalts are different from those of typical arc magmas,which are commonly characterized by high Cl contents(median of~1200 ppm)and low F/Cl ratios(<1).The observed differences can be attributed to chromatographic reaction that fractionates elements of different compatibility in the metasomatic agents,with amphibole as the main mineral phase for fractionating and preserving F and *** is,amphibole crystallization prefers to retain F rather than Cl,making the metasomes in vein enriched in F and exhibiting elevated F/Cl ratios compared to original metasomatic *** is further suggested that the scenario inferred from the Dabeigou basalts mi

关键词： North China Craton Sub-continental lithosphere mantle Early Cretaceous Dabeigou basalts Melt inclusion F and Cl cycling

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Paleomapping:Creating testable visual hypotheses of ancient worlds

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Journal of Palaeogeography 2025年第01期14卷 91-104页

作者： Holger Petermann Annaka M.Clement Patrick M.Sullivan Hannah M.Bonner James W.Hagadorn Department of earth and Space sciences Denver Museum of Nature & Science Colorado School of mines Department of Geology and Geologic Engineering Division of Water Quality Utah Department of Environmental Quality

The story of the earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the earth sciences. However, no formal procedure for the creation of photorealistic paleomaps(i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review,iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are wellsupported by outcrop and subsurface data, and where such visualization is highly interpretive-often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced,data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.

关键词： Ancient landscapes Cartography Paleogeography Paleoenvironments Jurassic

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Impacts of the annual cycle of background SST in the tropical Pacific on the phase and amplitude of ENSO

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 12-17页

作者： Song Jiang Congwen Zhu Ning Jiang State Key Laboratory of Severe Weather(LASW) Chinese Academy of Meteorological SciencesBeijingChina college of earth and Planetary sciences University of Chinese Academy of SciencesBeijingChina

The dominant annual cycle of sea surface temperature(SST)in the tropical Pacific exhibits an antisymmetric mode,which explains 83.4%total variance,and serves as a background of El Niño-Southern Oscillation(ENSO).However,there is no consensus yet on its anomalous impacts on the phase and amplitude of *** on data during 1982-2022,results show that anomalies of the antisymmetric mode can affect the evolution of ENSO on the interannual scale via Bjerknes feedback,in which the positive(negative)phase of the antisymmetric mode can strengthen El Niño(La Niña)in boreal winter via an earlier(delayed)seasonal cycle transition and larger(smaller)annual *** magnitude of the SST anomalies in the equatorial eastern Pacific can reach more than±0.3◦C,regulated by the changes in the antisymmetric mode based on random sensitivity *** reveal the spatial pattern of the annual cycle associated with the seasonal phase-locking of ENSO evolution and provide new insight into the impact of the annual cycle of background SST on ENSO,which possibly carries important implications for forecasting ENSO.

关键词： Annual cycle SST anomaly Antisymmetric mode ENSO

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Spatiotemporal evolution of wildfire activity during the Paleocene-Eocene Thermal Maximum in China

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Science China earth sciences 2025年第2期68卷 509-522页

作者： Xue-Ting WANG Zuoling CHEN Linlin CUI Xu WANG State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of sciences College of Earth and Planetary SciencesBeijing 100049China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

The Paleocene-Eocene Thermal Maximum(PETM)was the most prominent warming event in the Cenozoic and serves as a geological analog for the current global warming driven by anthropogenic CO_(2)emissions from burning fossil *** a primary disruptor of earth's ecosystems,wildfire activity affects the balance of ecosystems,the global carbon cycle,and climate ***,studying the evolution and driving mechanisms of wildfires during the PETM is essential for predicting wildfire activity under global warming scenarios and for understanding the carbon cycle in the context of wildfire *** research on wildfires during the PETM has mainly focused on the Northern Hemisphere,particularly Europe and North America,whereas studies on Chinese mainland remain *** this study,we analyzed black carbon(BC)concentration and carbon isotope(δ13C)in the Beigou section of the Nanyang Basin and the Xilutian section of the Fushun Basin to reconstruct the spatiotemporal evolution of wildfires in arid/semi-arid and humid *** integrated these findings with those of previous studies on the paleoclimate of the research area to elucidate the driving mechanisms behind wildfire *** results indicate that wildfire activity weakened at the onset of the PETM,with the negative carbon isotope period characterized by low wildfire activity,except for a brief resurgence in the Nanyang *** the recovery phase of the PETM,wildfire activity gradually increased,returning to the pre-PETM *** prolonged low wildfire state was likely caused by extremely high temperatures and precipitation as well as the resulting vegetation *** the PETM recovery phase,increased wildfire activity transformed“short-term carbon sinks”of the biological-atmospheric carbon cycle into“long-term carbon sinks”through the burial of *** process of carbon sink conversion may have acted as a negative feedback mechanism,contributing to carbon sequestration and the e

关键词： PETM Wildfire Carbon cycle Nanyang Basin Fushun Basin

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An investigation on the wind profiles and gravity wave dynamics in MLT region based on the meteor radars from the Meridian Project

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earth and Planetary Physics 2025年第1期9卷 29-38页

作者： Tai Liu Zhe Wang MengXi Shi Willie Soon ShiCan Qiu Department of Geophysics College of the Geology Engineering and GeomaticsChang’an UniversityXi’an 710054China Center for Environmental Research and earth sciences(CERES) SalemMA 01970USA Institute of earth Physics and Space Science(ELKH EPSS) 9400SopronHungary

The meteor radar can detect the zenith angle,azimuth,radial velocity,and altitude of meteor trails so that one can invert the wind profiles in the mesosphere and low thermosphere(MLT)region,based on the Interferometric and Doppler *** this paper,the horizontal wind field,gravity wave(GW)disturbance variance,and GW fluxes are analyzed through the meteor radar observation from 2012−2022,at Mohe(53.5°N,122.4°E)and Zuoling(30.5°N,114.6°E)stations of the(Chinese)Meridian *** Lomb−Scargle periodogram method has been utilized to analyze the periodic variations for time series with observational data *** results show that the zonal winds at both stations are eastward dominated,while the meridional winds are southward *** variance of GW disturbances in the zonal and meridional directions increases gradually with height,and there is a strong pattern of annual *** zonal momentum flux of GW changes little with height,showing weak annual *** meridional GW flux varies gradually from northward to southward with height,and the annual periodicity is *** both stations,the maximum values of zonal and meridional wind occur close to the peak heights of GW flux,with opposite *** observational evidence is consistent with the filtering *** horizontal wind velocity,GW flux,and disturbance variance of the GW at Mohe are overall smaller than those at Zuoling,indicating weaker activities in the MLT at *** power spectral density(PSD)calculated by the Lomb−Scargle periodogram shows that there are 12-month period and 6-month period in horizontal wind field,GW disturbance variance and GW flux at both stations,and especially there is also a 4-month cycle in the disturbance *** PSD of the 12-month and 6-month cycles exhibits maximum values below 88 km and above 94 km.

关键词： meteor radar wind field gravity wave Lomb−Scargle method

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