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Structure of the mantle transition zone in the central and western parts of the North China Craton using the receiver function 3D Kirchhoff migration method

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Science China Earth Sciences 2024年第9期67卷 2783-2795页

作者： Min ZHU Qingju WU Jieyuan NING Ruiqing ZHANG institute of {1. China Earthquake AdministrationBeijing 100081China institute of Theoretical and Applied {1. Peking UniversityBeijing 100871China

Using data from the regional broadband dense temporary array deployed by the ChinArray project,we applied the three-dimensional(3D)Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone(MTZ)in the central and western parts of the North China Craton(NCC)using a highresolution 3D velocity model of the East Asian *** results show that the 41.-km discontinuity beneath the Datong Volcano is depressed by~1. km,indicating the presence of a high-temperature anomaly near the depth of 41. km,which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the *** upwelling of hot material provides a heat source for surface magmatic *** the Bohai Bay Basin,significant subsidence of the 660-km discontinuity is observed,and the transition zone here is extensively ***’s suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the *** the thickness of the transition zone west of the North-South Gravity Lineament appears normal,we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the *** comparison,the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the ***,a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling *** is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate.

关键词： North China Craton Mantle transition zone Receiver function migration Datong Volcano

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3D and 2D topographic correction to estimated geothermal gradient from the base of gas hydrate stability zone in the Andaman Forearc Basin

Energy Geoscience

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Energy Geoscience 2024年第2期5卷 314-320页

作者： Uma Shankar Department of geophysics Institute of ScienceBHUVaranasiIndia

Methane gas hydrate related bottom-simulating reflectors(BSRs)are imaged based on the in-line and cross-line multi-channel seismic(MCS)data from the Andaman Forearc *** depth of the BSR depends on pressure and temperature and pore water *** these assumptions,the BSR depth can be used to estimate the geothermal gradient(GTG)based on the availability of in-situ temperature *** calculation is done assuming a 1. conductive model based on available in-situ temperature measurement at site NGHP-01.1. in the study ***,in the presence of seafloor topography,the conductive temperature field in the subsurface is affected by lateral refraction of heat,which focuses heat in topographic lows and away from topographic *** 1. estimate of GTG in the Andaman Forearc Basin has been validated by drilling results from the NGHP-01.expedition.2D analytic modeling to estimate the effects of topography is performed earlier along selected seismic profiles in the study *** study extended to estimate the effect of topography in 3D using a numerical *** corrected GTG data allow us to determine GTG values free of topographic *** difference between the estimated GTG and values corrected for the 3D topographic effect varies up to~5℃/*** conclude that the topographic correction is relatively small compared to other uncertainties in the 1. model and that apparent GTG determined with the 1. model captures the major features,although the correction is needed prior to interpreting subtle features of the derived GTG maps.

关键词： Gas hydrate BSR Geothermal gradient 3D and 2D topographic modeling Andaman Forearc Basin

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Crustal and uppermost mantle structure of the northeastern Qinghai-Xizang Plateau from joint inversion of surface wave dispersions and receiver functions with P velocity constraints

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Earthquake Science 2024年第2期37卷 93-106页

作者： Pei Zhang Xiaodong Song Jiangtao Li Xingchen Wang Xuezhen Zhang institute of {1. China Earthquake AdministrationBeijing 100081China The Second Monitoring and Application Center China Earthquake AdministrationXi'an 710054China institute of Theoretical and Applied {1. School of Earth and Space SciencesPeking UniversityBeijing 100871China Department of geophysics School of Geodesy and GeomaticsWuhan UniversityWuhan 430079China

Lithospheric structure beneath the northeastern Qinghai-Xizang Plateau is of vital significance for studying the geodynamic processes of crustal thickening and expansion of the Qinghai-Xizang Plateau. We conducted a joint inversion of receiver functions and surface wave dispersions with P-wave velocity constraints using data from the Chin Array Ⅱ temporary stations deployed across the Qinghai-Xizang Plateau. Prior to joint inversion, we applied the H-κ-c method(Li JT et al., 201.) to the receiver function data in order to correct for the back-azimuthal variations in the arrival times of Ps phases and crustal multiples caused by crustal anisotropy and dipping interfaces. High-resolution images of vS, crustal thickness, and vP/vSstructures in the Qinghai-Xizang Plateau were simultaneously derived from the joint inversion. The seismic images reveal that crustal thickness decreases outward from the Qinghai-Xizang Plateau. The stable interiors of the Ordos and Alxa blocks exhibited higher velocities and lower crustal vP/vSratios. While, lower velocities and higher vP/vSratios were observed beneath the Qilian Orogen and Songpan-Ganzi terrane(SPGZ), which are geologically active and mechanically weak, especially in the mid-lower *** or thermal erosion of the lithosphere triggered by hot asthenospheric flow contributes to the observed uppermost mantle low-velocity zones(LVZs) in the SPGZ. The crustal thickness, vS, and vP/vSratios suggest that whole lithospheric shortening is a plausible mechanism for crustal thickening in the Qinghai-Xizang Plateau, supporting the idea of coupled lithospheric-scale deformation in this region.

关键词： joint inversion receiver functions surface waves crustal thickness vP/vS ratio NE Qinghai-Xizang Plateau

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Source model of the 201. M_(w)7.5 Papua New Guinea earthquake constrained by InSAR measurements: Insight into a blind rupture beneath the New Guinea Highlands

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geodesy and Geodynamics 2024年第4期15卷 315-325页

作者： Wei Chen Tianchen Sheng Wei Xiong Key Laboratory of Earthquake geodesy Institute of SeismologyChina Earthquake AdministrationWuhan 430071China Qinghai Provincial Basic Surveying and Mapping institute Xining 810001China School of geodesy and Geomatics Wuhan UniversityWuhan 430079China

The Southern Highland Fold and Thrust Belt(SHFTB),the boundary of the Australian plate and the New Guinea Highland block,significantly contributes to the convergent deformation along the plate ***,due to the lack of observation data,the detailed slip pattern of the SHFTB and the orogenic mechanism beneath the New Guinea Highlands remains *** 25 February 201.,the M_(w)7.5 Papua New Guinea(PNG)earthquake struck the southeastern segment of the *** detailed rupture characteristics of this event is significant for further clarifying the inter-seismic slip pattern along the ***,the coseismic deformation field of this earthquake was obtained using high-resolution ALOS-2 satellite *** find that the 201. M_(w)7.5 PNG earthquake ruptured a large-scaled fault(SHFTB)extending to the lower crust(deeper than 20 km)beneath the New Guinea Highlands,with a dip angle of 24°.The slips on the fault plane are equivalent to moment magnitudes of M_(w)*** major asperities with thrust-dominated slip of up to 3.94 m are detected on the fault *** finding implies that the slip pattern on the eastern segment of the SHFTB is dominated by thrust,rather than with significant sinistral movement,as previously *** tectonic deformation across the New Guinea Highlands is possibly concentrated on the large-scale fault SHFTB and primarily controls the intra-continental orogeny in the central Papua New Guinea.

关键词： 201.M_(w)7.5PapuaNewGuineaearthquake The Southern Highlands Fold-and-Thrust Belt InSAR Slipdistribution Seismicrisk

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Mantle avalanches in a Venus-like stagnant lid planet

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Earth and Planetary Physics 2024年第5期8卷 686-702页

作者： Madeleine C.Kerr Dave R.Stegman institute of {1. and Planetary Physics Scripps Institution of Oceanography University of California

Stagnant lid planets are characterized by a globe-encircling, conducting lid that is thick and strong, which leads to reduced global surface heat flows. Consequently, the mantles of such planets can have warmer interiors than Earth, and interestingly, a pyrolitic mantle composition under warmer conditions is predicted to have a distinctly different mantle transition zone compared to the present-day Earth(Hirose, 2002; Stixrude and Lithgow-Bertelloni, 201.; Ichikawa et al., 201.; Dannberg et al, 2022). Instead of olivine primarily transforming into its higher-pressure polymorphs such as wadsleyite and then ringwoodite, at pressures corresponding to41. km and 520 km depth in Earth, respectively, it instead transforms into a mineral assemblage of wadsleyite, majorite, and ferropericlase(WMF), and then to majorite + ferropericlase(MF), before finally transforming into bridgmanite at pressures corresponding to 660 km depth in Earth(Stixrude and Lithgow-Bertelloni, 201.; Ichikawa et al., 201.). Convective motions in stagnant lid planets are dominated by small-scale instabilities(cold drips) forming within the mobile rheological sublayer under the rigid lid. Using ASPECT and a thermodynamic model of a pyrolitic mantle composition generated by HeFESTo, we show that under certain conditions, the small drips can pond atop the WMF-MF mineral phase transition. The barrier to convective flow arises from the WMF mineral phase assemblage having an effective negative thermal expansivity(Stixrude and Lithgow-Bertelloni, 2022). Although large-scale downwellings that typically occur within mobile lid planets are able to pass through the WMF zone without difficulty(Dannberg et al., 2022; Li RP et al.,2024), the smaller and less negatively buoyant nature of downwelling drips in stagnant lid planets are more susceptible to these effects,which leads to an ephemeral layering of the mantle. Our numerical models show that in stagnant lid planets with mantle potential temperatures that exceed

关键词： Venus mantle avalanches numerical modelling phase transitions

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Key issues on magnetic reconnection at Mercury

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Earth and Planetary Physics 2024年第5期8卷 673-685页

作者： Jun Zhong Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences

Magnetic reconnection processes and their impact on planetary magnetospheric dynamics exhibit significant differences due to differences in upstream solar wind conditions and internal planetary environments. Current understanding of reconnection phenomena at Mercury is rooted in the MESSENGER mission. However, direct detection of reconnection remains rare. Here, we aim to assess the limitations of MESSENGER in detecting reconnection in Mercury's space and to discuss key issues of reconnection that will be addressed by BepiColombo, including the dynamics of magnetic flux ropes, particle acceleration, density asymmetric reconnection,IMF-driven near-tail structures, and potential modes of magnetospheric convection.

关键词： magnetic reconnection Mercury MESSENGER BepiColombo

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Rock physical characteristics of deep dolomite under complex geological conditions: A case study of 4th Member of Sinian Dengying Formation in the Sichuan Basin, China

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Petroleum Science 2024年第4期21卷 2370-2382页

作者： Chuang Li Shu-Xin Pan Hong-Bin Wang Ji-Xin Deng Jian-Guo Zhao Zhi Li Yu Zhang Northwest Branch of Research institute of Petroleum Exploration & Development Department of geophysics and Exploration College of Geophysics Chengdu University of Technology State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing)

The deep-ultra deep carbonate reservoir in China, commonly subjected to modification of multi-stage diagenesis, has extremely high heterogeneity. Conventional rock physics analysis cannot accurately identify the elastic responses of reservoir. Here, the rock physics properties of the dolomite from the 4th Member of the Sinian Dengying Formation are experimentally measured, and the change law of rock physics characteristics is investigated within the framework of the diagenetic processes by the analysis of the elastic and petrologic characteristics, pore structure, and sedimentary environments. The results show that the differentiated diagenesis results in different pore structure characteristics and microtexture characteristics of the rock. The microbial dolomite of the algal mound-grain beach facies is subjected to the contemporaneous microbial dolomitization and seepage-reflux dolomitization, penecontemporaneous selective dissolution, burial dolomitization, and hydrothermal dolomitization. The resultant crystalline dolomite is found with one main type of the dolomite crystal contact boundaries,and the dissolution pore is extensive development. The siliceous, muddy, and limy dolomite of the interbeach sea environment mainly experiences the weak capillary concentration dolomitization, intensive mechanical compaction-induced densification, and burial dolomitization. Such crystalline dolomite is observed with four types of contact boundaries, namely the dolomite contact, clay contact, quartz contact, and calcite contact boundaries, and porosity mostly attributed to residual primary inter-granular or crystalline pores. The samples with the same crystal boundary condition have consistent correlations between the compressional-and shear-wave velocities, and between the compressional-wave velocity and the velocity ratio. Additionally, the variation of the acoustic velocity with effective pressure and the intensity of pore-scale fluid-related dispersion are controlled by t

关键词： Deep-ultra deep carbonate reservoirs Rock physics properties Dolomite Seismic elastic properties Micro-crack Pore structure types

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Spatial continuous modeling of early Cenozoic carbon cycle and climate

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National Science Review 2024年第4期11卷 30-32页

作者： Yonggang Liu Jian Zhang Haoyue Zuo Zhilin He Jiaqi Guo Qifan Lin Haonan Yu Jiawenjing Lan Jing Han Zhihong Song Zihan Yin Liang Zhao Yongyun Hu Zhengtang Guo Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

The partial pressure of atmospheric CO2（pCO2） is determined by the carbon cycle that involves climate, biogeochemistry, and plate tectonics. In this cycle,atmospheric CO2is converted into organic carbon and carbonates by biological activities and silicate weathering, and buried as sediments. The sediments on the ocean floor are subducted into the Earth’s interior, and subsequently converted back into CO2and outgassed into the atmosphere.

关键词： ATMOSPHERIC CO2

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Variations of shear-wave splitting parameters in the source region of the 2023 Türkiye doublet earthquakes

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Earthquake Science 2024年第2期37卷 174-187页

作者： Xuelai Cao Lijun Chang institute of {1. China Earthquake AdministrationBeijing 100081China

In this study,the shear-wave splitting parameters of local seismic events from the source regions of the 2023 Türkiye MW7.7 and MW7.6 doublet earthquakes(event 1.and event 2,respectively)were measured from June 1.2022,to April 25,2023,and their spatiotemporal characteristics were *** results revealed clear spatial and temporal ***,the dominant fast-wave polarization direction at each station shows a strong correlation with the direction of the maximum horizontal principal compressive stress,as characterized by focal mechanism solutions of seismic events(MW≥3.5)near the *** dominant fast-wave polarization direction and the regional stress field also showed a strong correlation with the intermovement of the Arabian Plate,African Plate,and Anatolian *** the Nurdagi-Pazarcik fault zone,the seismic fault of event 1.stations closer to the middle of the fault where the mainshock occurred exhibited notably greater delay times than stations located towards the ends of the fault and far from the *** addition,the stations located to the east of the Nurdagi-Pazarcik fault and to the north of the Sürgüfault also exhibited large delay *** spatial distribution of shear-wave splitting parameters obtained from each station indicates that the upper-crust anisotropy in the source area is mainly controlled by the regional stress field,which is closely related to the state of the block *** the seismogenic process of the MW7.7 earthquake,more stress accumulated in the middle of the Nurdagi-Pazarcik fault than at either end of the *** the influence of the MW7.7 and MW7.6 events,the stress that accumulated during the seismogenic process of the earthquake doublet may have migrated towards some areas outside the aftershock intensive area after the earthquakes,and the crustal stress and its adjustment range near the outer stations increased *** the exception of two stations with few effective events,all

关键词： Türkiye doublet earthquakes shear-wave splitting upper crustal anisotropy stress field

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On the eigenvalues and eigendisplacement of the critical mode in horizontally layered media

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Earthquake Science 2024年第1期37卷 13-35页

作者： Shaotong Wang Laiyu Lu The institute of {1. China Earthquake AdministrationBeijing 100081China

Wave propagation in horizontally layered media is a classical problem in seismic-wave *** semi-infinite space,a nondispersive Rayleigh wave mode exists,and the eigendisplacement decays exponentially with *** a layered model with increasing layer velocity,the phase velocity of the Rayleigh wave varies between the S-wave velocity of the bottom half-space and that of the classical Rayleigh wave propagated in a supposed half-space formed by the parameters of the top *** the phase velocity is the same as the P-or S-wave velocity of the layer,which is called the critical mode or critical phase velocity of surface waves,the general solution of the wave equation is not a homogeneous(expressed by trigonometric functions)or inhomogeneous(expressed by exponential functions)plane wave,but one whose amplitude changes linearly with depth(expressed by a linear function).Theories based on a general solution containing only trigonometric or exponential functions do not apply to the critical mode,owing to the singularity at the critical phase *** this study,based on the classical framework of generalized reflection and transmission coefficients,the propagation of surface waves in horizontally layered media was studied by introducing a solution for the linear function at the critical phase ***,the eigenvalues and eigenfunctions of the critical mode can be calculated by solving a singular *** eigendisplacement characteristics associated with the critical phase velocity were investigated for different layered *** contrast to the normal mode,the eigendisplacement associated with the critical phase velocity exhibits different *** the phase velocity is equal to the S-wave velocity in the bottom half-space,the eigendisplacement remains constant with increasing depth.

关键词： dispersion curve eigenvalue generalized reflection and transmission coefficient surface wave guide wave

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