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Constraints on the spin-state transition of siderite from laboratory-based Raman spectroscopy and electrical conductivity under high temperature and high pressure

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Geoscience Frontiers 2025年第1期16卷 321-333页

作者： Xinyu Zhang Lidong Dai Haiying Hu Meiling Hong Chuang Li Key Laboratory of High-temperature and High-pressure study of the earth's interior Institute of GeochemistryChinese Academy of SciencesGuiyangGuizhou 550081China University of Chinese Academy of sciences Beijing 100049China

The vibrational and electrical transport properties of natural siderite are systematically investigated by means of in-situ Raman spectroscopy and alternating current impedance spectroscopy under conditions of 0.6-55.6 GPa,298-873 K and different hydrostatic environments using a diamond anvil cell(DAC).Upon non-hydrostatic compression,all of these observable characteristic variations of siderite including the appearance of three absolutely new Raman peaks(L’,v4'and v1'),the disappearance of Raman peaks(T,L and v4)and the discontinuity in the pressure-dependent electrical conductivity can provide robust evidence of electronic spin transitions of Fe^(2+)from high-spin to mixed-spin to low-spin states at the respective pressures of 42.5 GPa and 48.5 *** far as hydrostatic condition,the electronic spin states from high-spin to mixed-spin to low-spin states occurred at the higher pressures of 45.7 GPa and 50.4 GPa,respectively,which implied the highly sensitive hydrostaticity of electronic spin transition *** decompression,the reverse electronic spin transitions from low-spin to mixed-spin to high-spin states were detected at the respective pressures of 47.2 GPa and 28.7 GPa under non-hydrostatic condition,and as well as at the pressures of 49.4 GPa and 25.1 GPa under hydrostatic condition,*** huge pressure hysteresis of 13.8 GPa and 20.6 GPa for the electronic spin state transition was revealed under non-hydrostatic and hydrostatic environments,*** order to explore the effect of temperature on the electronic spin transition,a series of electrical conductivity experiments on siderite were performed over the temperature range of 323-873 K under conditions of three typical pressures of 47.7,49.8 and 51.6 ***,the functional relationships between the temperature and pressure describing the high-spin to mixed-spin to low-spin transitions for siderite were successfully established:P1(GPa)=39.318+0.015 T(K)and P2(GPa)=41.277+0.

关键词： siderite Electronic spin transition Raman spectroscopy Electrical conductivity High temperature High pressure

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Constraints on what controls millennial-scale basin-wide denudation across mountain belts,Asia

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science China earth sciences 2025年第1期68卷 74-93页

作者： Ye YANG steven A.BINNIE sheng XU Cong-Qiang LIU Tibor J.DUNAI institute of surface-earth system science School of Earth System ScienceTianjin UniversityTianjin300072China institute of Geology and Mineralogy University of CologneCologne50674Germany

The terrestrial cosmogenic nuclide dataset consisting of 1233^(10)Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on earth-surface denudation processes.^(10)Be-derived basin-wide denudation rates were recalculated using a Monte Carlo simulation approach that relied on pixel-by-pixel production *** rates derived span four orders of magnitude,from 7.4±0.7 mm kyr^(-1)(1σ;Central Tibetan Plateau)to 9,646_(-744)^(+777)mm kyr^(-1)(1σ;southern Tibetan Plateau),with a median of 186 mm kyr^(-1).Comparing our results with the traditional basin-wide production rate scaling model using a centroid coordinate and mean elevation,suggests that 96.6%of production rates will be underestimated using the latter method,especially for basins with a large *** bias between both methods reaches as large as 40%,caused by basin hypsometry and the nonlinear scaling of production rate with elevation and *** of the correlations between uniformly recalculated denudation rates and tectonics,climate,topography and rock lithology will facilitate the extrapolation of denudation rates in unknown basins using available *** the perspective of local scales,precipitation coupled with neotectonics-driven landslides is likely the most influential factor in subtropical Taiwan Island,while topography primarily constrains surface denudation rates in the eastern Tibetan Plateau within a narrow range of *** highland regions with glacier coverage,such as the Pamir,central and southern Tibetan Plateau high denudation rates are affected by glaciation,whereas lower precipitation and high erosion base level may limit river incision and evolving relief in the Central Tibetan *** contrast to local-scale findings highlighting a dominant factor constraining denudation rate,our large-scale quantitative analyses across the Asian mountain belts finds that(1)topographic

关键词： ^(10)Be-derived denudation rate Climate change Tectonic uplift Topographic gradient Asian mountains

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Viscosities of hcp iron alloys under earth’s inner core conditions

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Geoscience Frontiers 2025年第1期16卷 383-392页

作者： Yunfan Xu Yu He shichuan sun Wei Zhang Weiru Dai Duck Young Kim Heping Li Key Laboratory of High-Temperature and High-Pressure study of the earth's interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081GuizhouChina University of Chinese Academy of sciences Beijing 100049China Center for High Pressure science and Technology Advanced Research Shanghai 201203China Asian school of the Environment Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore school of Geography and Environmental science(school of Karst science) Guizhou Normal UniversityGuiyang 550025China

Viscosity is critical for controlling the dynamics and evolution of the earth’s inner core(IC).The viscosities of hexagonal close-packed(hcp)and body-centred cubic(bcc)Fe were studied experimentally and theoretically under earth's core ***,earth’s inner core is mainly composed of Fe-Ni alloys with some light element impurities(si,s,C,H,O),and the influence of impurities(Ni,si,s,C,H,and O)on viscosity is still *** this study,the diffusion coefficients of Fe,Ni,si,s,C,H,and O were calculated under IC conditions using ab initio molecular dynamics(AIMD)and deep learning molecular dynamics(DPMD)*** them,C,H,and O are highly diffusive like liquids in the lattice,while Fe,Ni,si,and s diffuse through Fe site *** binary alloys,the influence of these impurities(Ni:12.5%,s:3.6%,si:3.1%,C:1.3%,O:1.7%,H:0.4%by weight)on viscosity is *** on the dislocation creep mechanism,the predicted viscosities of the hcp Fe alloys are 1×10^(14)-2×10^(16)Pa·s,which is consistent with the values predicted by free inner core nutation and seismic wave attenuation observations.

关键词： earth’s inner core High pressure and high temperature Viscosity Molecular dynamics

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High-resolution shallow structures of the Red River fault zone in the southeastern Tibetan Plateau of China revealed by multiple seismic dense linear arrays

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earth and Planetary Physics 2025年第2期9卷 195-211页

作者： HongYu Ni JunLun Li Bao Deng JinYu Zhang YuanChao Lu Yan Zhao JianYe Chen Peng su Laboratory of seismology and Physics of the earth’s interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Anhui earthquake Agency Hefei 230031China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 233500China state Key Laboratory of earthquake Dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China Anhui Key Laboratory of subsurface Exploration and earthquake Hazard Risk Prevention(in prep.)

The complex Red River fault zone(RRFZ), which is situated in the southwestern region of China and separates the Indochina plate and south China blocks, has diverse seismic activities in different segments. To reveal the detailed geometric characteristics of the RRFZ at different sections and to better understand the seismogenic environment, in 2022 and 2023 we deployed 7 seismic dense linear arrays, consisting of 574 nodal stations, across the RRFZ in the northern and southern segments near the towns Midu, Gasa, Zhega,Dazhai, Xinzhai, and Taoyuan. The linear arrays, which extend from 2.4 to 12.5 km in length with station intervals ranging between 40 and140 m, recorded seismic ambient noise for approximately one month. Using the extended range phase shift method, we extract the phase velocity dispersion curves of the Rayleigh waves between 0.9 and 10 Hz, which are then used to invert for the high resolution shearwave velocity structures across the RRFZ beneath the linear arrays. The key findings are:(1) the 7 imaged sections of the RRFZ exhibit quite similar structures, with higher velocities on the sW side and lower velocities on the NE side;the velocity variation is consistent with the surface geological structures along the RRFZ;(2) the shear-wave velocities on the sW side of the RRFZ at the northern Midu section and southern Gasa-Dazhai sections are generally higher than their counterparts in the southern Xinzhai-Taoyuan sections, which reflects lithological variations from the marble-dominated Paleoproterozoic Along basement to the gneiss dominated Paleoproterozoic Qingshuihe basement;(3) from the northern Midu section to the southern region where the RRFZ intersects with the Xiaojiang Fault, the major faults of the RRFZ exhibit a consistent high-angle, NE-dipping structure;(4) the low shear-wave velocities immediately to the NE of the velocity boundary may indicate a faulted zone due to long-term shearing, where excessive amplifications of ground motions could

关键词： Red River fault zone shallow fault structure seismic dense array ambient noise tomography extended range phase shift method

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earthquake monitoring and high-resolution velocity tomography for the central Longmenshan fault zone by a temporary dense seismic array

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earth and Planetary Physics 2025年第2期9卷 239-252页

作者： shaoBo Yang HaiJiang Zhang MaoMao Wang Ji Gao shuaijun Wang BaoJin Liu XiWei Xu school of Carbon Neutrality science and Engineering Anhui University of Science and TechnologyHefei 231131China Laboratory of seismology and Physics of earth’s interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China institute of Tectonics and Geophysics College of OceanographyHohai UniversityNanjing 210098China Geophysical Exploration Center China Earthquake AdministrationZhengzhou 450002China school of earth sciences and Resources China University of GeosciencesBeijing 100083China

The Longmenshan(LMs) fault zone is located at the junction of the eastern Tibetan Plateau and the sichuan Basin and is of great significance for studying regional tectonics and earthquake hazards. Although regional velocity models are available for the LMs fault zone, high-resolution velocity models are lacking. Therefore, a dense array of 240 short-period seismometers was deployed around the central segment of the LMs fault zone for approximately 30 days to monitor earthquakes and characterize fine structures of the fault zone. Considering the large quantity of observed seismic data, the data processing workflow consisted of deep learning-based automatic earthquake detection, phase arrival picking, and association. Compared with the earthquake catalog released by the China earthquake Administration, many more earthquakes were detected by the dense array. Double-difference seismic tomography was adopted to determine V_(p), V_(s), and V_(p)/V_(s) models as well as earthquake locations. The checkerboard test showed that the velocity models have spatial resolutions of approximately 5 km in the horizontal directions and 2 km at depth. To the west of the Yingxiu–Beichuan Fault(YBF), the Precambrian Pengguan complex, where most of earthquakes occurred, is characterized by high velocity and low V_(p)/V_(s) values. In comparison, to the east of the YBF, the Upper Paleozoic to Jurassic sediments, where few earthquakes occurred, show low velocity and high V_(p)/V_(s) values. Our results suggest that the earthquake activity in the LMs fault zone is controlled by the strength of the rock compositions. When the high-resolution velocity models were combined with the relocated earthquakes, we were also able to delineate the fault geometry for different faults in the LMs fault zone.

关键词： Longmenshan fault zone dense seismic array deep learning double-difference seismic tomography seismic velocity model earthquake locations fault geometry

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Three-dimensional internal multiple elimination in complex structures using Marchenko autofocusing theory

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Petroleum science 2025年第1期22卷 222-233页

作者： Pei-Nan Bao Ying shi Xin-Min shang Hong-Xian Liang Wei-Hong Wang school of earth sciences Northeast Petroleum University Geophysical Research institute of shengli Oilfield Sinopec

Internal multiples are commonly present in seismic data due to variations in velocity or density of subsurface media. They can reduce the signal-to-noise ratio of seismic data and degrade the quality of the image. With the development of seismic exploration into deep and ultradeep events, especially those from complex targets in the western region of China, the internal multiple eliminations become increasingly challenging. Currently, three-dimensional(3D) seismic data are primarily used for oil and gas target recognition and drilling. Effectively eliminating internal multiples in 3D seismic data of complex structures and mitigating their adverse effects is crucial for enhancing the success rate of drilling. In this study, we propose an internal multiple prediction algorithm for 3D seismic data in complex structures using the Marchenko autofocusing theory. This method can predict the accurate internal multiples of time difference without an accurate velocity model and the implementation process mainly consists of several steps. Firstly, simulating direct waves with a 3D macroscopic velocity ***, using direct waves and 3D full seismic acquisition records to obtain the upgoing and downgoing Green's functions between the virtual source point and surface. Thirdly, constructing internal multiples of the relevant layers by upgoing and downgoing Green's functions. Finally, utilizing the adaptive matching subtraction method to remove predicted internal multiples from the original data to obtain seismic records without multiples. Compared with the two-dimensional(2D) Marchenko algorithm, the performance of the 3D Marchenko algorithm for internal multiple prediction has been significantly enhanced, resulting in higher computational accuracy. Numerical simulation test results indicate that our proposed method can effectively eliminate internal multiples in 3D seismic data,thereby exhibiting important theoretical and industrial application value.

关键词： Marchenko Internal multiple elimination Autofocusing Three-dimensional seismic data

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Reconstruction of stress trajectory field in Nankai subduction zone based on drilling data

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Journal of Rock Mechanics and Geotechnical Engineering 2025年第2期17卷 747-756页

作者： Nikita Dubinya Alexander Galybin schmidt institute of Physics of the earth RAs Moscow123242Russia Moscow institute of Physics and Technology Dolgoprudny141701Russia

This paper presents some results of stress field reconstruction in the Nankai Trough subduction zone located within the area bounded by 136.3°–137°E and 33°–33.5°N where 12 scientific wells were drilled during Nankai Trough seismogenic Zone Experiment expeditions of the Integrated Ocean Drilling Program and International Ocean Discovery *** use the logging data to derive orientations of the maximum principal stress axis at different depths followed by the reconstruction of stress orientations in each individual *** these data,we further derive average stress orientations along the wells and use these data to reconstruct the stress trajectory field taking into account the presence of Megasplay *** results are shown as the stress trajectories of the maximum principal horizontal *** are generally consistent with data the World stress Map Project data.

关键词： stress trajectory stress field reconstruction Nankai trough subduction zone

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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

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earth and Planetary Physics 2025年第2期9卷 225-238页

作者： Xin Liu HuaJian Yao CuiPing Zhao Ying Liu song Luo Laboratory of seismology and Physics of earth’s interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China institute of Advanced Technology University of Science and Technology of ChinaHefei 230088China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng Hefei 233500China Chinese Academy of sciences(CAs)Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China institute of earthquake Forecasting China Earthquake AdministrationBeijing 100036China school of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China

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 ***, 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 ***, 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.

关键词： Zemuhe–Xiaojiang Fault Zone shallow crust s-wave velocity ambient noise tomography microseismicity

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shear softening of earth's inner core as indicated by its high poisson ratio and elastic anisotropy

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Fundamental Research 2025年第1期5卷 264-268页

作者： Zhongqing Wu Wenzhong Wang Laboratory of seismology and Physics of earth's interior School of Earth and Space ScienceUniversity of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China CAs Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China

earth's inner core exhibits an unusually high Poisson ratio and noticeable elastic *** mechanisms responsible for these features are crucial to understanding the nature of earth's *** different mechanisms have been proposed,few can explain both observations *** results of this study indicated that the crystal with noticeable shear softening would have strong anisotropy and an exceptionally high Poisson ratio ***-centered-cubic(bcc)iron exhibits shear instability at inner-core pressures and can be dynamically stabilized by high temperature and the presence of light *** bcc-lattice iron alloy could have strong anisotropy and a Poisson ratio of earth's inner core before shear *** which light elements can stabilize the bcc-lattice iron alloy will provide an independent constraint on the chemical composition of the inner core.

关键词： Elasticity Crystal structure Iron alloy earth’s interior Composition

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Geochemistry of shales of middle Permian Barren Measures Formation,West Bokaro Basin,India:Implications on provenance,paleodepositional and paleoclimatic conditions

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Journal of Palaeogeography 2025年第1期14卷 40-65页

作者： Mritunjoy Banerjee Biplab Bhattacharya Arnab Bhattacharya Aniruddha Pathak Partha Pratim Banerjee Department of earth sciences Indian Institute of Technology Natural Resource Division Tata Steel Limited

Geochemical analyses of fine-grained clastic sedimentary rocks,such as shales,are significant since they portray the nature of the control factors from source to sink in a sedimentary basin,and help characterizing the heterogeneity in potential source and/or reservoir *** rock geochemistry（including major element oxides,trace elements and rare earth elements） of 20 shale samples from the Permian Barren Measures Formation,West Bokaro Basin,Peninsular India,is presented to decipher the provenance,paleoweathering,paleotectonic,paleodepositional and paleoredox conditions of the basin within the Lower Gondwana paleogeographic framework.X-ray diffraction（XRD） peaks and scanning electron microscopy（sEM）reveal an abundance of quartz,muscovite and clay minerals,viz.,illite,kaolinite,etc.,with less abundant feldspar and *** concentrations of major element oxides,trace elements and rare earth elements（REEs） of the shale samples are compared with predefined standards such as PAAs and *** CIA（chemical index of alteration） and the A-CN-K values,based on the ratios of the major element oxides,signify intense chemical *** ratios of sr/Cu versus Rb/sr and K2O/Al2O3versus Ga/Rb,and high ∑REE values indicate a temperate *** of the major element oxides（e.g.,K2O/Na2O versus siO2） suggest a passive tectonic *** Eu/Eu*and（Gd/Yb）_n values depict predominantly post-Archean granitic and gneissic source *** ratios of trace elements,viz.,Th/sc,Th/Co,Th/Cr,La/sc and Eu/Eu*,and the distribution pattern of the REEs（higher LREE in comparison to HREE） attest to a felsic-intermediate source from a nearby *** redox-sensitive trace elements,such as V and Ni,indicate a dysoxic condition that prevailed during *** ratios of Fe2O3versus MgO and Log（MgO/Al2O3） versus Log（K2O/Al2O3）,and the ternary plots of Fe2O3-MgO-siO2/Al2O3suggest a non-marine to deltaic transitional *** evidence of marine influences during

关键词： Guadalupian Lower Gondwana Passive margin rift basin Fluvial–marine transition Anoxic condition West Bokaro Basin

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