Shibaozhai area is located in the northeast Sichuan Basin in Southwest China.In recent years,oil and gas reservoirs with abundant reserves have been discovered in nearby areas.Six magnetotelluric(MT)survey lines were ...Shibaozhai area is located in the northeast Sichuan Basin in Southwest China.In recent years,oil and gas reservoirs with abundant reserves have been discovered in nearby areas.Six magnetotelluric(MT)survey lines were arranged to investigate the deep geoelectrical structures and hidden faults that controlled the hydrocarbon migration along the eastern Kaijiang–Liangping trough and Dachiganjing tectonic belt in this area.The MT sounding data for 181 sites,which covered an area of 15×6 km,were collected.Twodimensional transverse-magnetic-mode inversion of the data revealed four geoelectric layers with a total thickness of approximately 10 km.A low resistivity layer with a thickness of 4 km was discovered in the middle of the exploration area.The combination of faults within the study area revealed a northeast-direction thrust-fault system,which was displaced by northwest-direction faults.The regional geological structures played a significant role in controlling hydrocarbon and gas accumulation.The results of this study could be beneficial in analyzing the geological structure of hydrocarbon reservoirs in this area and can be extended to the exploration of areas in the boundary of a basin.展开更多
Wavefield extrapolation is critical in reverse time migration(RTM).The finite diff erence method is primarily used to achieve wavefi eld extrapolation in case of the RTM imaging of tunnels.However,complex tunnel model...Wavefield extrapolation is critical in reverse time migration(RTM).The finite diff erence method is primarily used to achieve wavefi eld extrapolation in case of the RTM imaging of tunnels.However,complex tunnel models,including those for karsts and fault fracture zones,are constructed using regular grids with straight curves,which can cause numerical dispersion and reduce the imaging accuracy.In this study,wavefi eld extrapolation was conducted for tunnel RTM using the finite element method,wherein an unstructured mesh was considered to be the body-fi tted partition in a complex model.Further,a Poynting vector calculation equation suitable for the unstructured mesh considered in the fi nite element method was established to suppress the interference owing to low-frequency noise.The tunnel space was considered during wavefi eld extrapolation to suppress the mirror artifacts based on the fl exibility of mesh generation.Finally,the infl uence of the survey layouts(one and two sidewalls)on the tunnel imaging results was investigated.The RTM results obtained for a simple tunnel model with an inclined interface demonstrate that the method based on unstructured meshes can effectively suppress the low-frequency noise and mirror artifacts,obtaining clear imaging results.Furthermore,the two-sidewall tunnel survey layout can be used to accurately obtain the real position of the inclined interface ahead of the tunnel face.The complex tunnel numerical modeling and actual data migration results denote the eff ectiveness of the fi nite element method in which an unstructured mesh is used.展开更多
INTRODUCTION.On January 7,2025,at 9:05 AM BJT,a MS6.8 earthquake(CENC epicenter:28.50°N,87.45°E)struck Dingri County,Xizang Province(hereinafter referred to as the Dingri mainshock).The inferred moment magni...INTRODUCTION.On January 7,2025,at 9:05 AM BJT,a MS6.8 earthquake(CENC epicenter:28.50°N,87.45°E)struck Dingri County,Xizang Province(hereinafter referred to as the Dingri mainshock).The inferred moment magnitude,based on regional/teleseismic waveform inversion and back-projection,is approximately MW7.1.Focal mechanism solutions,aftershock distribution,and field surveys indicate that the Dingri mainshock was a normal-faulting event,with a nearly north-south strike and a westward-dipping fault plane.展开更多
The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic...The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.展开更多
The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.Howeve...The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.However,the inversion for the ES model suffers from nonuniqueness and instability,which remain unresolved.To mitigate these issues,we introduce both the minimum and flattest models into the model objective function as an alternative regularization approach in the spherical ES method.We first present the methods,then analyze the accuracy of forward calculation and test the proposed ES method in this study by using synthetic data.The experimental results from simulation data indicate that our proposed regularization effectively suppresses the Backus effect and mitigates inversion instability in the low-latitude region.Finally,we apply the proposed method to magnetic anomaly data from China Seismo-Electromagnetic Satellite-1(CSES-1)and Macao Science Satellite-1(MSS-1)magnetic measurements over Africa by constructing an ES model of the large-scale lithospheric magnetic field.Compared with existing global lithospheric magnetic field models,our ES model demonstrates good consistency at high altitudes and predicts more stable fields at low altitudes.Furthermore,we derive the reduction to the pole(RTP)magnetic anomaly fields and the apparent susceptibility contrast distribution based on the ES model.The latter correlates well with the regional tectonic framework in Africa and surroundings.展开更多
As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal vari...As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal variations in the lithosphere.Traditional approaches either do not consider the non-axial dipolar terms of the inducing field and its radial variation or do so by means of complicated formulae.Moreover,existing methods treat the magnetic lithosphere either as an infinitesimally thin layer or as a radially uniform spherical shell of constant thickness.Here,we present alternative forward formulae that account for an arbitrarily high maximum degree of the inducing field and for a magnetic lithosphere of variable thickness.Our simulations based on these formulae suggest that the satellite magnetic anomaly field is sensitive to the non-axial dipolar terms of the inducing field but not to its radial variation.Therefore,in forward and inverse calculations of satellite magnetic anomaly data,the non-axial dipolar terms of the inducing field should not be ignored.Furthermore,our results show that the satellite magnetic anomaly field is sensitive to variability in the lateral thickness of the magnetized shell.In particular,we show that for a given vertically integrated susceptibility distribution,underestimating the thickness of the magnetic layer overestimates the induced magnetic field.This discovery bridges the greatest part of the alleged gap between the susceptibility values measured from rock samples and the susceptibility values required to match the observed magnetic field signal.We expect the formulae and conclusions of this study to be a valuable tool for the quantitative interpretation of the Earth's global lithospheric magnetic field,through an inverse or forward modelling approach.展开更多
The CUG_CLMFM3D series comprises high-resolution three-dimensional lithospheric magnetic field models for China and its surroundings.The first version,CUG_CLMFM3Dv1,is a spherical cap harmonic model integrating the WD...The CUG_CLMFM3D series comprises high-resolution three-dimensional lithospheric magnetic field models for China and its surroundings.The first version,CUG_CLMFM3Dv1,is a spherical cap harmonic model integrating the WDMAMv2(World Digital Magnetic Anomaly Map version 2)global magnetic anomaly grid and nearly a decade of CHAMP(Challenging Minisatellite Payload for Geophysical Research and Application)satellite vector data.It achieves a~5.7 km resolution but has limitations:the WDMAMv2 grid lacks high-resolution data in the southern Xinjiang and Tibet regions,which leads to missing small-to medium-scale anomalies,and unfiltered CHAMP data introduce low-frequency conflicts with global spherical harmonic models.Above the altitude of 150 km,correlations with global models drop below 0.9.The second version,CUG_CLMFM3Dv2,addresses these issues by incorporating 5-km-resolution aeromagnetic data and rigorously processed satellite data from CHAMP,Swarm,CSES-1(China Seismo-Electromagnetic Satellite 1),and MSS-1(Macao Science Satellite 1).The comparison analysis shows that the CUG_CLMFM3Dv2 captures finer high-frequency details and more stable long-wavelength signals,offering improved magnetic anomaly maps for further geological and geophysical studies.展开更多
The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized ...The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized lithosphere,and the space current systems.Modeling of the lithospheric contribution plays an important role in the geophysical studies and industrial applications.In this paper,we propose a new method for global and regional modeling of the lithospheric magnetic field based on the cubed-sphere.An equivalent dipole source method on a quasi-uniform cubed-sphere grid is employed in the forward modeling.The dipole directions are fixed according to a priori magnetization and the relative intensities are estimated by an inversion procedure of least-squares fitting with minimum model regularization.Several numerical tests are performed to validate the accuracy and efficiency of both forward modeling and inversion procedure.The proposed method is applied to the global and regional modeling based on the latest magnetic data from Swarm Alpha satellite and MSS-1 mission.The model results indicate that the proposed method works quite well for realistic satellite data and MSS-1 data is consistent with the Swarm data in terms of lithospheric field modeling.展开更多
The data of marine-controlled source electromagnetic exploration collected in shallow waters are considerably influenced by airwaves.Thus,finding ways to eliminate this influence is important.Decomposing the electroma...The data of marine-controlled source electromagnetic exploration collected in shallow waters are considerably influenced by airwaves.Thus,finding ways to eliminate this influence is important.Decomposing the electromagnetic field into the upgoing and downgoing fields is an effective method to resolve this problem.By utilizing the Stratton-Chu integral transform,this study proposes a novel method that can separate a 3D electromagnetic field into upgoing and downgoing electromagnetic fields through rigorous mathematical deduction.We examine the spectral characteristics to determine the effectiveness of the method.The results show that a practical digital filter can be achieved by selecting a reasonable window size and spatial step,as demonstrated through spectral comparisons with an analytical filter.展开更多
On 3 July 2015, a Mw 6.4 earthquake occurred on a blind fault struck Pishan, Xinjiang,China. By combining Crustal Movement Observation Network of China（CMONOC） and other Static Global Positioning System（GPS） sites...On 3 July 2015, a Mw 6.4 earthquake occurred on a blind fault struck Pishan, Xinjiang,China. By combining Crustal Movement Observation Network of China（CMONOC） and other Static Global Positioning System（GPS） sites surrounding Pishan region, it provides a rare chance for us to constrain the slip rupture for such a moderate event. The maximum displacement is up to 12 cm, 2 cm for coseismic and postseismic deformation, respectively,and both the deformation patterns show a same direction moving northeastward. With rectangular dislocation model, a magnitude of Mw6.48, Mw6.3 is calculated based on coseismic, postseismic deformation respectively. Our result indicates the western Kunlun range is still moving toward Tarim Basin followed by an obvious postseismic slip associated with this earthquake. To determine a more reasonable model for postseismic deformation, a longer GPS dataset will be needed.展开更多
The Marwar Supergroup(NW Peninsular India)is thought to be of Ediacaran-Cambrian age,based on previous paleontological and geochronological studies.However,direct constraints on the onset of sedimentation within the M...The Marwar Supergroup(NW Peninsular India)is thought to be of Ediacaran-Cambrian age,based on previous paleontological and geochronological studies.However,direct constraints on the onset of sedimentation within the Marwar basin are still scarce.In this study,we report U–Pb zircon,LA-ICP-MS,and SIMS ages from the Chhoti Khatu felsic volcanic rocks,interlayered with the Jodhpur Group sandstones(Lower Marwar Supergroup).The cathodoluminescence images of the zircons indicate complex morphologies,and core-rim textures coupled with the wide range of ages indicate that they are likely inherited or in the case of thin poorly indurated ash-beds,detrital in origin.The age spectra of 68 zircon analyses from our sampling display a dominant 800–900 Ma age peak corresponding to the age of basement"Erinpura granite"rocks in the region.The youngest inherited zircon from a felsic ash layer yielded a U–Pb age of651 Ma±18 Ma that,together with previous studies and paleontological evidence,indicates a postCryogenian age for the initiation of Marwar sedimentation following a~125 Ma hiatus between the end of Malani magmatism and Marwar deposition.展开更多
The Lomagundi(-Jatuli)event,characterized by extremely high positive global inorganic carbon isotope excursion at about 2.2 billion years ago,is pivotal in investigating the causes and consequences of great oxygenatio...The Lomagundi(-Jatuli)event,characterized by extremely high positive global inorganic carbon isotope excursion at about 2.2 billion years ago,is pivotal in investigating the causes and consequences of great oxygenation event,inventory and sequestration of carbon on the Earth’s surface,evolution of life,and more profoundly tectonic control on Earth’s environment.However,the reasons that caused the isotopic excursion are not resolved yet.Herein,we report the discovery of meta-carbonate rocks with distinct positive carbon isotopic excursion from the Paleoproterozoic continental collision zone of the Kongling Complex,South China Craton.The δ^(13)C_(V-PDB) values for meta-carbonate rocks show positive values in the range from+5.5‰to+11.6‰,whereas the δ^(13)C_(V-PDB) values of associated graphite deposits range from-25.8‰to-9.5‰.Zircon U-Pb-Hf isotopes from zircon-bearing meta-carbonate sample yielded weighted average _(207)Pb/_(206)Pb age of 2001.3±9.5 Ma,with correspondingε_(Hf)(t)range from-7.05 to-3.16,comparable to the values of local 2.9–2.6 Ga basement rocks.Geochemical characteristics of meta-carbonate rocks,such as their rare earth element patterns and the trace element parameters of La,Ce,Eu,and Gd anomalies and Y/Ho ratio,suggest that the carbonate deposition took place in passive continental margin in association with large volumes of organic carbon.The extensive graphite deposits from Kongling Complex in South China Craton,their equivalents in the North China Craton and elsewhere across the globe prove that the burial of ^(12)C-enriched organic carbon has eventually resulted in the global enrichment of ^(13)C in the atmospheric CO_(2),which is recorded in the marine carbonate rocks.Isotopic mass balance estimates indicate that more than half of the organic carbon was buried during the oceanic closure.Hence,the observed global shift could be directly related to the continent collision event in greater China,thus resolving the long-standing paradox of the Lomagundi global positive carbon isotope excursion.Moreover,the present results suggest that orogenesis play a significant role in sequestration of carbon into the continental crust.展开更多
The airwave effect greatly influences the observational data from controlledsource electromagnetic exploration in shallow seas, which obscures the abnormal effects generated by exploration targets and, hence, affects ...The airwave effect greatly influences the observational data from controlledsource electromagnetic exploration in shallow seas, which obscures the abnormal effects generated by exploration targets and, hence, affects the accuracy of the late exploration data interpretation. In this study, we propose a method to separate the main part from the anomalous field of marine controlled-source electromagnetic method （MCSEM） data based on Stratton-Chu integral transforms to eliminate the airwave effect, which dominates observed electromagnetic （EM） response in shallow seawater. This method of separating the main part from the anomalous field is a type of finite impulse response filter based on a discrete data set. Theoretical analysis proved that the method is stable and able to effectively depress noise. A numerical test indicated that the method could successfully eliminate the airwave effect from the observed EM signals generated by an air water interface and a seawater layer. This technique is applicable for seawater models with either flat or rough seabeds.展开更多
High-locality landslides are located on slopes at high elevations and are characterized by long sliding distances, large gravitational potential energy, high movement velocities, tremendous kinetic energy, and sudden ...High-locality landslides are located on slopes at high elevations and are characterized by long sliding distances, large gravitational potential energy, high movement velocities, tremendous kinetic energy, and sudden onset. Thus, they often cause catastrophic damage to human lives and engineering facilities. It is of great significance to identify active high-locality landslides in their early deformational stages and to reveal their deformational rules for effective disaster mitigation. Due to alpinecanyon landforms, Mao County is a representative source of high-locality landslides. This work employs multisource data(geological, terrain, meteorological, ground sensor, and remote sensing data) and timeseries In SAR technology to recognize active high-locality landslides in Mao County and to reveal their laws of development. Some new viewpoints are suggested.(1) Nineteen active high-locality landslides are identified by the time-series In SAR technique, of which 7 are newly discovered in this work. All these high-locality landslides possessed good concealment during their early deformational stages. The newly discovered HL-16 landslide featured a large scale and a great slope height, posing a large threat to the surrounding buildings and residents.(2) The high-locality landslides in Mao County were mainly triggered by three factors: earthquakes, precipitation, and road construction.(3) Three typical high-locality landslides that were triggered by different factors are highlighted with their deformational rules under the functions of steep terrain, shattered rocks, fissure-water penetration, precipitation, and road construction. This work may provide clues to the prevention and control of high-locality landslides and can be applied to the determination of active high-locality landslides in other hard-hit areas.展开更多
Dynamic earthquake triggering as a well-documented phenomenon can provide valuable information for studying the stress loading cycle from failure on faults.In this study,seismicity rate changes were investigated in th...Dynamic earthquake triggering as a well-documented phenomenon can provide valuable information for studying the stress loading cycle from failure on faults.In this study,seismicity rate changes were investigated in the Longitudinal Valley fault(LVF)following the 2019 M_(L)5.2 Hualien earthquake,which occurred offshore in eastern Taiwan.After the matched filter technique was applied to continuous waveform data,twice as many microearthquakes were newly detected in the vicinity of the LVF compared with the number listed in the Taiwan Weather Bureau catalog.Seismicity rates in the northern segment of the LVF increased immediately following the Hualien mainshock,which indicated dynamic triggering during the passage of seismic waves.Statistical analysis suggested that following seismic events might be attributed to fault slipping or creeping.These findings show that the observation of earthquake triggering can provide valuable assistance in monitoring the stress perturbations of active faults.展开更多
On April 20, 2013, an M_s 7.0 earthquake struck Lushan County in Sichuan Province, China, and caused serious damage to the source region. We investigated the rupture process of the M_s7.0 Lushan earthquake by jointly ...On April 20, 2013, an M_s 7.0 earthquake struck Lushan County in Sichuan Province, China, and caused serious damage to the source region. We investigated the rupture process of the M_s7.0 Lushan earthquake by jointly inverting waveforms of teleseismic P waveforms and local strong motion records as well as static GPS observations. The inverted results indicate that the rupture of this earthquake was dominated by the failure of an asperity with a triangular shape and that the main shock was dominated by thrust slip. The earthquake released a total seismic moment of 1.01× 10^（19）Nm, with 92% of it being released during the first 11 s. The rupture had an average slip of 0.9 m and produced an average stress drop of 1.8 MPa. Compared with our previous work that was based mainly on a unique dataset, this joint inversion result is more consistent with field observations and the distribution of aftershock zones.展开更多
The 1605 M7½ Earthquake is the only earthquake in the history of China that has caused large-scale land subsidence into the sea,with the total area of land subsidence exceeding 100 km2.The disaster has led to the...The 1605 M7½ Earthquake is the only earthquake in the history of China that has caused large-scale land subsidence into the sea,with the total area of land subsidence exceeding 100 km2.The disaster has led to the sinking of 72 villages.There is still no clear understanding of the source seismogenic fault of this earthquake.In this work,we conducted a detailed study of the middle segment of the Maniao-Puqian fault(MPF),which is the epicenter area,through geomorphological survey,data collection,shallow seismic exploration,cross-section drilling,and chronological dating.The results showed that the middle segment of the MPF zone is composed of three nearly parallel normal faults with a dextral strike-slip:“Macun-Luodou fault(F2-1),Haixiu-Dongyuan fault(F2-2),and ChangliuZhuxihe fault(F2-3)”.And F2-2 is composed of two secondary faults,namely F2-2′and F2-2″,with a flower-shaped structure buried under the ground.It is distributed nearly east-west,dipping to the north and has experienced at least five stages of activities since the Miocene.The vertical activity rates of F2-2′and F2-2″are~2.32 and~2.5 mm/a,since the Holocene,respectively.There were eight cycles of transgression and regression since the Miocene.The fault activity resulted in the thickening of the Holocene strata with a slight dip to the south,on the hanging wall,showing V-shaped characteristics.The MPF is likely the source seismogenic fault of the M7½ earthquake that hit Qiongshan in 1605.展开更多
In this study,a deep learning algorithm was applied to two-dimensional magnetotelluric(MT)data inversion.Compared with the traditional linear iterative inversion methods,the MT inversion method based on convolutional ...In this study,a deep learning algorithm was applied to two-dimensional magnetotelluric(MT)data inversion.Compared with the traditional linear iterative inversion methods,the MT inversion method based on convolutional neural networks(CNN)does not rely on the selection of the initial model parameters and does not fall into the local optima.Although the CNN inversion models can provide a clear electrical interface division,their inversion results may remain prone to abrupt electrical interfaces as opposed to the actual underground electrical situation.To solve this issue,a neural network with a residual network architecture(ResNet-50)was constructed in this study.With the apparent resistivity and phase pseudo-section data as the inputs and with the resistivity parameters of the geoelectric model as the training labels,the modified ResNet-50 model was trained end-to-end for producing samples according to the corresponding production strategy of the study area.Through experiments,the training of the ResNet-50 with the dice loss function effectively solved the issue of over-segmentation of the electrical interface by the cross-entropy function,avoided its abrupt inversion,and overcame the computational inefficiency of the traditional iterative methods.The proposed algorithm was validated against MT data measured from a geothermal field prospect in Huanggang,Hubei Province,which showed that the deep learning method has opened up broad prospects in the field of MT data inversion.展开更多
The deformation mechanisms of the Tianshan orogenic belt(TOB)are one of the most important unresolved issues in the collision of the Indian and Eurasian plates.To better understand the lithospheric deformation of the ...The deformation mechanisms of the Tianshan orogenic belt(TOB)are one of the most important unresolved issues in the collision of the Indian and Eurasian plates.To better understand the lithospheric deformation of the eastern Tianshan orogenic belt,we combined the S-wave tomography and gravity data to develop a three-dimensional(3D)density model of the crust and upper mantle beneath the eastern Tianshan area.Results show that the crust of the eastern Tianshan is mainly characterized by positive density anomalies,revealing widespread subduction-related magmatism during the Paleozoic.We however have also observed extensive low-density anomalies beneath the eastern Tianshan at depths deeper than~100 km,which is likely linked to a relatively hot mantle.The most fundamental differences of the lithosphere within the eastern Tianshan occur in the uppermost mantle.The uppermost mantle layers in the Bogda Shan and Harlik Shan are relatively dense.This is likely associated with an eclogite body in the uppermost mantle.The most significant negative anomaly of the uppermost mantle is however found in the Jueluotage tectonic belt and the central Tianshan Block and is possibly associated with depleted mantle material.We suggest that these differences related to compositional changes may control the strength of the lithospheric mantle and have affected the uplift of the northern and southern segments of the eastern Tianshan after the Permian.展开更多
A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cuttin...A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cutting. It can reconstruct several compressed signals simultaneously even without any prior information of the sparsity, which makes it a potential candidate for many practical applications, but the numbers of non-zero(significant) coefficients of signals are not available. Numerical experiments are conducted to demonstrate the validity and high performance of the proposed algorithm, as compared to other existing strong DCS algorithms.展开更多
基金supported by the National Natural Science Foundation of China(42074085,and 41574067).
文摘Shibaozhai area is located in the northeast Sichuan Basin in Southwest China.In recent years,oil and gas reservoirs with abundant reserves have been discovered in nearby areas.Six magnetotelluric(MT)survey lines were arranged to investigate the deep geoelectrical structures and hidden faults that controlled the hydrocarbon migration along the eastern Kaijiang–Liangping trough and Dachiganjing tectonic belt in this area.The MT sounding data for 181 sites,which covered an area of 15×6 km,were collected.Twodimensional transverse-magnetic-mode inversion of the data revealed four geoelectric layers with a total thickness of approximately 10 km.A low resistivity layer with a thickness of 4 km was discovered in the middle of the exploration area.The combination of faults within the study area revealed a northeast-direction thrust-fault system,which was displaced by northwest-direction faults.The regional geological structures played a significant role in controlling hydrocarbon and gas accumulation.The results of this study could be beneficial in analyzing the geological structure of hydrocarbon reservoirs in this area and can be extended to the exploration of areas in the boundary of a basin.
基金supported by the National Natural Science Foundation of China (Nos. 41804145, 41704146)Natural Science Foundation of Hebei Province (No. D2018210168)Project of Hebei Province Higher Educational Science and Technology Program (No.QN2019185)。
文摘Wavefield extrapolation is critical in reverse time migration(RTM).The finite diff erence method is primarily used to achieve wavefi eld extrapolation in case of the RTM imaging of tunnels.However,complex tunnel models,including those for karsts and fault fracture zones,are constructed using regular grids with straight curves,which can cause numerical dispersion and reduce the imaging accuracy.In this study,wavefi eld extrapolation was conducted for tunnel RTM using the finite element method,wherein an unstructured mesh was considered to be the body-fi tted partition in a complex model.Further,a Poynting vector calculation equation suitable for the unstructured mesh considered in the fi nite element method was established to suppress the interference owing to low-frequency noise.The tunnel space was considered during wavefi eld extrapolation to suppress the mirror artifacts based on the fl exibility of mesh generation.Finally,the infl uence of the survey layouts(one and two sidewalls)on the tunnel imaging results was investigated.The RTM results obtained for a simple tunnel model with an inclined interface demonstrate that the method based on unstructured meshes can effectively suppress the low-frequency noise and mirror artifacts,obtaining clear imaging results.Furthermore,the two-sidewall tunnel survey layout can be used to accurately obtain the real position of the inclined interface ahead of the tunnel face.The complex tunnel numerical modeling and actual data migration results denote the eff ectiveness of the fi nite element method in which an unstructured mesh is used.
基金supported by the“CUG Scholar”Scientific Research Funds at China University of Geosciences(Wuhan)(No.2021230)supported by the National Natural Science Foundation of China(Nos.41922025,42204062)。
文摘INTRODUCTION.On January 7,2025,at 9:05 AM BJT,a MS6.8 earthquake(CENC epicenter:28.50°N,87.45°E)struck Dingri County,Xizang Province(hereinafter referred to as the Dingri mainshock).The inferred moment magnitude,based on regional/teleseismic waveform inversion and back-projection,is approximately MW7.1.Focal mechanism solutions,aftershock distribution,and field surveys indicate that the Dingri mainshock was a normal-faulting event,with a nearly north-south strike and a westward-dipping fault plane.
基金supported by the National Natural Science Foundation of China (41804067, 42174090, 42250101, and 42250103)the Science Research Project of the Hebei Education Department (BJK2024107)+3 种基金the Hebei Natural Science Foundation (D2022403044)the Opening Fund of the Key Laboratory of Geological Survey and Evaluation of the Ministry of Education (GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources (MSFGPMR2022-4)the Excellent Young Scientist Fund of Hebei GEO University (YQ202403)。
文摘The lithospheric magnetic field is an important component of the geomagnetic field,and the oceanic lithosphere exhibits distinct characteristics.Because of its formation mechanisms,evolutionary history,and geomagnetic field polarity reversals,the oceanic lithosphere has significant remanent magnetization,which causes magnetic anomaly stripes parallel to the mid-ocean ridges.However,it is difficult to construct a high-resolution lithospheric magnetic field model in oceanic regions with relatively sparse data or no data.Using forward calculated lithospheric magnetic field data based on an oceanic remanent magnetization(ORM) model with physical and geological foundations as a supplement is a feasible approach.We first collect the latest available oceanic crust age grid,plate motion model,geomagnetic polarity timescale,and oceanic lithosphere thermal structure.Combining the assumptions that the paleo geomagnetic field is a geocentric axial dipole field and that the normal oceanic crust moves only in the horizontal direction,we construct a vertically integrated ORM model of the normal oceanic crust with a known age,including the intensity,inclination,and declination.Both the ORM model and the global induced magnetization(GIM) model are then scaled from two aspects between their forward calculated results and the lithospheric magnetic field model LCS-1.One aspect is the difference in their spherical harmonic power spectra,and the other is the misfit between the grid data over the oceans.We last compare the forward calculated lithospheric magnetic anomaly from the scaled ORM and GIM models with the Macao Science Satellite-1(MSS-1) observed data.The comparison results show that the magnetic anomalies over the normal oceanic crust regions at satellite altitude are mainly contributed by the high-intensity remanent magnetization corresponding to the Cretaceous magnetic quiet period.In these regions,the predicted and observed anomalies show good consistency in spatial distribution,whereas their amplitude differences vary across regions.This result suggests that regional ORM construction should be attempted in future work to address these amplitude discrepancies.
基金supported by the National Natural Science Foundation of China(Grant Nos.42250103 and 42174090)the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(Grant No.GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2022-4).
文摘The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.However,the inversion for the ES model suffers from nonuniqueness and instability,which remain unresolved.To mitigate these issues,we introduce both the minimum and flattest models into the model objective function as an alternative regularization approach in the spherical ES method.We first present the methods,then analyze the accuracy of forward calculation and test the proposed ES method in this study by using synthetic data.The experimental results from simulation data indicate that our proposed regularization effectively suppresses the Backus effect and mitigates inversion instability in the low-latitude region.Finally,we apply the proposed method to magnetic anomaly data from China Seismo-Electromagnetic Satellite-1(CSES-1)and Macao Science Satellite-1(MSS-1)magnetic measurements over Africa by constructing an ES model of the large-scale lithospheric magnetic field.Compared with existing global lithospheric magnetic field models,our ES model demonstrates good consistency at high altitudes and predicts more stable fields at low altitudes.Furthermore,we derive the reduction to the pole(RTP)magnetic anomaly fields and the apparent susceptibility contrast distribution based on the ES model.The latter correlates well with the regional tectonic framework in Africa and surroundings.
基金supported by the National Natural Science Foundation of China(Grant Nos.42250103 and 42174090)the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(Grant No.GLAB2023ZR02)the Ministry of Science and Technology(MOST)Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2022-4)。
文摘As a means of quantitative interpretation,forward calculations of the global lithospheric magnetic field in the Spherical Harmonic(SH)domain have been widely used to reveal geophysical,lithological,and geothermal variations in the lithosphere.Traditional approaches either do not consider the non-axial dipolar terms of the inducing field and its radial variation or do so by means of complicated formulae.Moreover,existing methods treat the magnetic lithosphere either as an infinitesimally thin layer or as a radially uniform spherical shell of constant thickness.Here,we present alternative forward formulae that account for an arbitrarily high maximum degree of the inducing field and for a magnetic lithosphere of variable thickness.Our simulations based on these formulae suggest that the satellite magnetic anomaly field is sensitive to the non-axial dipolar terms of the inducing field but not to its radial variation.Therefore,in forward and inverse calculations of satellite magnetic anomaly data,the non-axial dipolar terms of the inducing field should not be ignored.Furthermore,our results show that the satellite magnetic anomaly field is sensitive to variability in the lateral thickness of the magnetized shell.In particular,we show that for a given vertically integrated susceptibility distribution,underestimating the thickness of the magnetic layer overestimates the induced magnetic field.This discovery bridges the greatest part of the alleged gap between the susceptibility values measured from rock samples and the susceptibility values required to match the observed magnetic field signal.We expect the formulae and conclusions of this study to be a valuable tool for the quantitative interpretation of the Earth's global lithospheric magnetic field,through an inverse or forward modelling approach.
基金supported by the National Natural Science Foundation of China(Grant Nos.42250103,42174090,42250101,42250102,and 41774091)the Macao Foundation+1 种基金the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(Grant No.GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2022-4)。
文摘The CUG_CLMFM3D series comprises high-resolution three-dimensional lithospheric magnetic field models for China and its surroundings.The first version,CUG_CLMFM3Dv1,is a spherical cap harmonic model integrating the WDMAMv2(World Digital Magnetic Anomaly Map version 2)global magnetic anomaly grid and nearly a decade of CHAMP(Challenging Minisatellite Payload for Geophysical Research and Application)satellite vector data.It achieves a~5.7 km resolution but has limitations:the WDMAMv2 grid lacks high-resolution data in the southern Xinjiang and Tibet regions,which leads to missing small-to medium-scale anomalies,and unfiltered CHAMP data introduce low-frequency conflicts with global spherical harmonic models.Above the altitude of 150 km,correlations with global models drop below 0.9.The second version,CUG_CLMFM3Dv2,addresses these issues by incorporating 5-km-resolution aeromagnetic data and rigorously processed satellite data from CHAMP,Swarm,CSES-1(China Seismo-Electromagnetic Satellite 1),and MSS-1(Macao Science Satellite 1).The comparison analysis shows that the CUG_CLMFM3Dv2 captures finer high-frequency details and more stable long-wavelength signals,offering improved magnetic anomaly maps for further geological and geophysical studies.
基金supported by the National Natural Science Foundation of China(42250101,42250102,42250103,12250013)the Macao Foundation。
文摘The Earth's magnetic field,which has been extensively observed from ground to satellite altitudes over several decades,originates from multiple sources,such as the core dynamo,the conductive mantle,the magnetized lithosphere,and the space current systems.Modeling of the lithospheric contribution plays an important role in the geophysical studies and industrial applications.In this paper,we propose a new method for global and regional modeling of the lithospheric magnetic field based on the cubed-sphere.An equivalent dipole source method on a quasi-uniform cubed-sphere grid is employed in the forward modeling.The dipole directions are fixed according to a priori magnetization and the relative intensities are estimated by an inversion procedure of least-squares fitting with minimum model regularization.Several numerical tests are performed to validate the accuracy and efficiency of both forward modeling and inversion procedure.The proposed method is applied to the global and regional modeling based on the latest magnetic data from Swarm Alpha satellite and MSS-1 mission.The model results indicate that the proposed method works quite well for realistic satellite data and MSS-1 data is consistent with the Swarm data in terms of lithospheric field modeling.
基金supported by the National Natural Science Foundation of China(42074085).
文摘The data of marine-controlled source electromagnetic exploration collected in shallow waters are considerably influenced by airwaves.Thus,finding ways to eliminate this influence is important.Decomposing the electromagnetic field into the upgoing and downgoing fields is an effective method to resolve this problem.By utilizing the Stratton-Chu integral transform,this study proposes a novel method that can separate a 3D electromagnetic field into upgoing and downgoing electromagnetic fields through rigorous mathematical deduction.We examine the spectral characteristics to determine the effectiveness of the method.The results show that a practical digital filter can be achieved by selecting a reasonable window size and spatial step,as demonstrated through spectral comparisons with an analytical filter.
基金supported by National Natural Science Foundation of China(41304014,41204001,41274037 and 41431069)National 863 Project of China(2013AA122501)+4 种基金China postdoctoral science foundation(2015M57228)the Basic Fund of Hubei Subsurface Multi-scale Imaging Key Laboratory,Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan(SMIL-2015-01)the Fundamental Research Funds for National Universities(CUGL150810)China Scholarship Council(201506415072)the Basic Research Fund of Key Laboratory of Geospace Environment and Geodesy,Ministry of Education of China(13-02-11 and 14-01-01)
文摘On 3 July 2015, a Mw 6.4 earthquake occurred on a blind fault struck Pishan, Xinjiang,China. By combining Crustal Movement Observation Network of China（CMONOC） and other Static Global Positioning System（GPS） sites surrounding Pishan region, it provides a rare chance for us to constrain the slip rupture for such a moderate event. The maximum displacement is up to 12 cm, 2 cm for coseismic and postseismic deformation, respectively,and both the deformation patterns show a same direction moving northeastward. With rectangular dislocation model, a magnitude of Mw6.48, Mw6.3 is calculated based on coseismic, postseismic deformation respectively. Our result indicates the western Kunlun range is still moving toward Tarim Basin followed by an obvious postseismic slip associated with this earthquake. To determine a more reasonable model for postseismic deformation, a longer GPS dataset will be needed.
基金JGM by the US National Science Foundation Grant EAR09-10888HRX by the National Natural Science Foundation of China Grant 41974078。
文摘The Marwar Supergroup(NW Peninsular India)is thought to be of Ediacaran-Cambrian age,based on previous paleontological and geochronological studies.However,direct constraints on the onset of sedimentation within the Marwar basin are still scarce.In this study,we report U–Pb zircon,LA-ICP-MS,and SIMS ages from the Chhoti Khatu felsic volcanic rocks,interlayered with the Jodhpur Group sandstones(Lower Marwar Supergroup).The cathodoluminescence images of the zircons indicate complex morphologies,and core-rim textures coupled with the wide range of ages indicate that they are likely inherited or in the case of thin poorly indurated ash-beds,detrital in origin.The age spectra of 68 zircon analyses from our sampling display a dominant 800–900 Ma age peak corresponding to the age of basement"Erinpura granite"rocks in the region.The youngest inherited zircon from a felsic ash layer yielded a U–Pb age of651 Ma±18 Ma that,together with previous studies and paleontological evidence,indicates a postCryogenian age for the initiation of Marwar sedimentation following a~125 Ma hiatus between the end of Malani magmatism and Marwar deposition.
基金financial support from National Natural Science Foundation of China(41802200)Natural Science Foundation of Hubei Province(2020CFB863)+5 种基金China Scholarship Council(201906415017)China University of Geosciences Wuhan(CUGQY1938)the partial support through JSPS KAKENHI Grant Numbers JP15H05831 and 20KK0081a PhD scholarship support from Niigata Universityfinancial support from National Natural Science Foundation of China(41520104003)China University of Geosciences Wuhan(CUGCJ1709)。
文摘The Lomagundi(-Jatuli)event,characterized by extremely high positive global inorganic carbon isotope excursion at about 2.2 billion years ago,is pivotal in investigating the causes and consequences of great oxygenation event,inventory and sequestration of carbon on the Earth’s surface,evolution of life,and more profoundly tectonic control on Earth’s environment.However,the reasons that caused the isotopic excursion are not resolved yet.Herein,we report the discovery of meta-carbonate rocks with distinct positive carbon isotopic excursion from the Paleoproterozoic continental collision zone of the Kongling Complex,South China Craton.The δ^(13)C_(V-PDB) values for meta-carbonate rocks show positive values in the range from+5.5‰to+11.6‰,whereas the δ^(13)C_(V-PDB) values of associated graphite deposits range from-25.8‰to-9.5‰.Zircon U-Pb-Hf isotopes from zircon-bearing meta-carbonate sample yielded weighted average _(207)Pb/_(206)Pb age of 2001.3±9.5 Ma,with correspondingε_(Hf)(t)range from-7.05 to-3.16,comparable to the values of local 2.9–2.6 Ga basement rocks.Geochemical characteristics of meta-carbonate rocks,such as their rare earth element patterns and the trace element parameters of La,Ce,Eu,and Gd anomalies and Y/Ho ratio,suggest that the carbonate deposition took place in passive continental margin in association with large volumes of organic carbon.The extensive graphite deposits from Kongling Complex in South China Craton,their equivalents in the North China Craton and elsewhere across the globe prove that the burial of ^(12)C-enriched organic carbon has eventually resulted in the global enrichment of ^(13)C in the atmospheric CO_(2),which is recorded in the marine carbonate rocks.Isotopic mass balance estimates indicate that more than half of the organic carbon was buried during the oceanic closure.Hence,the observed global shift could be directly related to the continent collision event in greater China,thus resolving the long-standing paradox of the Lomagundi global positive carbon isotope excursion.Moreover,the present results suggest that orogenesis play a significant role in sequestration of carbon into the continental crust.
基金supported by the National Natural Science Foundation of China(No.41574067)863 Program(No.2012AA09A404)
文摘The airwave effect greatly influences the observational data from controlledsource electromagnetic exploration in shallow seas, which obscures the abnormal effects generated by exploration targets and, hence, affects the accuracy of the late exploration data interpretation. In this study, we propose a method to separate the main part from the anomalous field of marine controlled-source electromagnetic method （MCSEM） data based on Stratton-Chu integral transforms to eliminate the airwave effect, which dominates observed electromagnetic （EM） response in shallow seawater. This method of separating the main part from the anomalous field is a type of finite impulse response filter based on a discrete data set. Theoretical analysis proved that the method is stable and able to effectively depress noise. A numerical test indicated that the method could successfully eliminate the airwave effect from the observed EM signals generated by an air water interface and a seawater layer. This technique is applicable for seawater models with either flat or rough seabeds.
基金supported by the National Key Research and Development Program of China (No.2019YFC1511 304)the National Natural Science Foundation of China (Nos.U21A2013,42311530065)Hunan Provincial Natural Science Foundation of China (No.2021JC0009)。
文摘High-locality landslides are located on slopes at high elevations and are characterized by long sliding distances, large gravitational potential energy, high movement velocities, tremendous kinetic energy, and sudden onset. Thus, they often cause catastrophic damage to human lives and engineering facilities. It is of great significance to identify active high-locality landslides in their early deformational stages and to reveal their deformational rules for effective disaster mitigation. Due to alpinecanyon landforms, Mao County is a representative source of high-locality landslides. This work employs multisource data(geological, terrain, meteorological, ground sensor, and remote sensing data) and timeseries In SAR technology to recognize active high-locality landslides in Mao County and to reveal their laws of development. Some new viewpoints are suggested.(1) Nineteen active high-locality landslides are identified by the time-series In SAR technique, of which 7 are newly discovered in this work. All these high-locality landslides possessed good concealment during their early deformational stages. The newly discovered HL-16 landslide featured a large scale and a great slope height, posing a large threat to the surrounding buildings and residents.(2) The high-locality landslides in Mao County were mainly triggered by three factors: earthquakes, precipitation, and road construction.(3) Three typical high-locality landslides that were triggered by different factors are highlighted with their deformational rules under the functions of steep terrain, shattered rocks, fissure-water penetration, precipitation, and road construction. This work may provide clues to the prevention and control of high-locality landslides and can be applied to the determination of active high-locality landslides in other hard-hit areas.
基金supported by the Fundamental Research Founds for National University,China University of Geosciences(Wuhan)(No.1910491T09)the National Natural Science Foundation of China(No.42074061).
文摘Dynamic earthquake triggering as a well-documented phenomenon can provide valuable information for studying the stress loading cycle from failure on faults.In this study,seismicity rate changes were investigated in the Longitudinal Valley fault(LVF)following the 2019 M_(L)5.2 Hualien earthquake,which occurred offshore in eastern Taiwan.After the matched filter technique was applied to continuous waveform data,twice as many microearthquakes were newly detected in the vicinity of the LVF compared with the number listed in the Taiwan Weather Bureau catalog.Seismicity rates in the northern segment of the LVF increased immediately following the Hualien mainshock,which indicated dynamic triggering during the passage of seismic waves.Statistical analysis suggested that following seismic events might be attributed to fault slipping or creeping.These findings show that the observation of earthquake triggering can provide valuable assistance in monitoring the stress perturbations of active faults.
基金supported by a grant from the Chinese Earthquake Administration (No.201308013)the National Natural Science Foundation of China (Nos.41604057, 40974034, and 41021003)a key project from the Institute of Geodesy and Geophysics
文摘On April 20, 2013, an M_s 7.0 earthquake struck Lushan County in Sichuan Province, China, and caused serious damage to the source region. We investigated the rupture process of the M_s7.0 Lushan earthquake by jointly inverting waveforms of teleseismic P waveforms and local strong motion records as well as static GPS observations. The inverted results indicate that the rupture of this earthquake was dominated by the failure of an asperity with a triangular shape and that the main shock was dominated by thrust slip. The earthquake released a total seismic moment of 1.01× 10^（19）Nm, with 92% of it being released during the first 11 s. The rupture had an average slip of 0.9 m and produced an average stress drop of 1.8 MPa. Compared with our previous work that was based mainly on a unique dataset, this joint inversion result is more consistent with field observations and the distribution of aftershock zones.
基金supported by the National Natural Science Foundation of China(No.42272222)the Basic Research Funds of Institute of Geomechanics,Chinese Academy of Geological Sciences(No.DZLXJK202211)China Geological Survey(Nos.DD20190306,DD20190546,DD20160269,DD20230249)。
文摘The 1605 M7½ Earthquake is the only earthquake in the history of China that has caused large-scale land subsidence into the sea,with the total area of land subsidence exceeding 100 km2.The disaster has led to the sinking of 72 villages.There is still no clear understanding of the source seismogenic fault of this earthquake.In this work,we conducted a detailed study of the middle segment of the Maniao-Puqian fault(MPF),which is the epicenter area,through geomorphological survey,data collection,shallow seismic exploration,cross-section drilling,and chronological dating.The results showed that the middle segment of the MPF zone is composed of three nearly parallel normal faults with a dextral strike-slip:“Macun-Luodou fault(F2-1),Haixiu-Dongyuan fault(F2-2),and ChangliuZhuxihe fault(F2-3)”.And F2-2 is composed of two secondary faults,namely F2-2′and F2-2″,with a flower-shaped structure buried under the ground.It is distributed nearly east-west,dipping to the north and has experienced at least five stages of activities since the Miocene.The vertical activity rates of F2-2′and F2-2″are~2.32 and~2.5 mm/a,since the Holocene,respectively.There were eight cycles of transgression and regression since the Miocene.The fault activity resulted in the thickening of the Holocene strata with a slight dip to the south,on the hanging wall,showing V-shaped characteristics.The MPF is likely the source seismogenic fault of the M7½ earthquake that hit Qiongshan in 1605.
基金co-funded by the National Natural Science Foundation of China(No.42220104002,42174095,U1812402,and 41630317)the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(No.GLAB2022ZR10)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan).
文摘In this study,a deep learning algorithm was applied to two-dimensional magnetotelluric(MT)data inversion.Compared with the traditional linear iterative inversion methods,the MT inversion method based on convolutional neural networks(CNN)does not rely on the selection of the initial model parameters and does not fall into the local optima.Although the CNN inversion models can provide a clear electrical interface division,their inversion results may remain prone to abrupt electrical interfaces as opposed to the actual underground electrical situation.To solve this issue,a neural network with a residual network architecture(ResNet-50)was constructed in this study.With the apparent resistivity and phase pseudo-section data as the inputs and with the resistivity parameters of the geoelectric model as the training labels,the modified ResNet-50 model was trained end-to-end for producing samples according to the corresponding production strategy of the study area.Through experiments,the training of the ResNet-50 with the dice loss function effectively solved the issue of over-segmentation of the electrical interface by the cross-entropy function,avoided its abrupt inversion,and overcame the computational inefficiency of the traditional iterative methods.The proposed algorithm was validated against MT data measured from a geothermal field prospect in Huanggang,Hubei Province,which showed that the deep learning method has opened up broad prospects in the field of MT data inversion.
基金supported by the National Natural Science Foundation of China(No.41774091).
文摘The deformation mechanisms of the Tianshan orogenic belt(TOB)are one of the most important unresolved issues in the collision of the Indian and Eurasian plates.To better understand the lithospheric deformation of the eastern Tianshan orogenic belt,we combined the S-wave tomography and gravity data to develop a three-dimensional(3D)density model of the crust and upper mantle beneath the eastern Tianshan area.Results show that the crust of the eastern Tianshan is mainly characterized by positive density anomalies,revealing widespread subduction-related magmatism during the Paleozoic.We however have also observed extensive low-density anomalies beneath the eastern Tianshan at depths deeper than~100 km,which is likely linked to a relatively hot mantle.The most fundamental differences of the lithosphere within the eastern Tianshan occur in the uppermost mantle.The uppermost mantle layers in the Bogda Shan and Harlik Shan are relatively dense.This is likely associated with an eclogite body in the uppermost mantle.The most significant negative anomaly of the uppermost mantle is however found in the Jueluotage tectonic belt and the central Tianshan Block and is possibly associated with depleted mantle material.We suggest that these differences related to compositional changes may control the strength of the lithospheric mantle and have affected the uplift of the northern and southern segments of the eastern Tianshan after the Permian.
基金Projects(61203287,61302138,11126274)supported by the National Natural Science Foundation of ChinaProject(2013CFB414)supported by Natural Science Foundation of Hubei Province,ChinaProject(CUGL130247)supported by the Special Fund for Basic Scientific Research of Central Colleges of China University of Geosciences
文摘A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cutting. It can reconstruct several compressed signals simultaneously even without any prior information of the sparsity, which makes it a potential candidate for many practical applications, but the numbers of non-zero(significant) coefficients of signals are not available. Numerical experiments are conducted to demonstrate the validity and high performance of the proposed algorithm, as compared to other existing strong DCS algorithms.
