Using the gravity anomaly dataset of the 1320 km long profile from Mandula (Inner Mongolia) in the south, through Mongolia to the Kachujia (Russia) in the north of Baikal, the 2D crustal density structure model has been constructed in this study. We have analyzed the deep structural features along with the Moho interface of the profile including the gravity anomaly, the crustal density structure, the interface undulation and fault distribution for each tectonic unit. This result can provide the proof of gravity field for the further understanding of the crustal structure of the area across the profile, the boundaries and correlations of tectonic units, and the related continental dynamics.

The Pamir plateau is the center of the confluence of the five mountain ranges, known as the western Himalayan syntaxis. It is inaccessible to the human being due to the high mountains and steep valleys. In this paper, we study the deep crustal structure and regional geological structure of the Pamir plateau region using two NNW and NEE trending crossing profiles with 1620 km in length, on which the limited ground gravity, artificial seismic data and satellite gravity data are available. Results show that the crustal thickness (the depth of Moho) in the central Pamir plateau is about 70 km, overall with a thinning trend (shallower) from the center to the rim, about 50 km in the surroundings of Pamir. This area is characterized by intense tectonic activity and obvious variation of crust and mantle structures.

For the purpose of calculating the gravity field model through spherical harmonic method only based on local measurements, it calculated that the measured gravity field data in mainland China by Slepian local spectrum method, and also it evaluated that the error effected by the non-uniformity of measured points by the known spherical harmonic model of GOCE satellite datasets.Firstly it calculated that the Slepian basis functions in mainland China and took the 72 order spherical harmonic model of GOCE satellite to evaluate the effective of the method in non-uniformity of measured points.Then, it recalculated that the gravity filed model by the Slepian localized spectral approach based on the resample points of Chinese mainland, and determined the gravity field variation model of Chinese mainland using the repeated gravity measure datasets from 2005 to 2008.

In order to investigate the structure of the crust beneath the Middle Qinling Mountains (MQL) and neighboring areas in the North China Block and South China Block, a north-south gravity profile from Yuquan in the Sichuan Basin to Yulin in the Ordos Basin was conducted in 2011. The Bouguer gravity anomaly is determined from a high-quality gravity dataset collected between 31 degrees N and 36 degrees N of latitude, and varies between -200 and -110 mGal in the study region. Using accredited velocity density relationships, an initial crust-mantle density model is constructed for MQL and adjacent areas, which is later refined interactively to simulate the observed gravity anomaly. The present study reveals the features of the density and Bouguer gravity with respect to the tectonic units sampled by the profile. The lithosphere density model shows typical density values that depict a layered structure and allow differentiate the blocks that extend along the reference profile. The gravity field calculated by forward modeling from the final density distribution model correlates well with the measured gravity field within a standard deviation of 1.26 mGal. The density in the crystalline crust increases with depth from 2.65 g/cm(3) up to the highest value of 2.95 g/cm(3) near the bottom of the crust. The Conrad interface is identified as a density jump of about 0.05 g/cm(3). The average density of the crust in MQL is clearly lower than the density in the formations on both sides. Starting from a combined Airy-Pratt isostatic compensation model, a partly compensated crust is found below MQL, suggesting future growth of the crust, unlike the Ordos and Sichuan basins that will remain stable. On the basis of the density and isostatic state of the crust and additional seismological research, such as the P-wave velocity model and Poisson's ratio, it is concluded that the lower crust delamination is a reasonable interpretation for the geophysical characteristics below the Qinling Orogen.

In order to investigate the structure of the crust beneath the Inner Mongolia tectonic belt, the Yinshan orogen, the North China Craton, the Qinling orogen, the Yangtze Craton and the intra-continental orogens in South China, a 2280 km long gravity survey profiling was conducted from Mandula town in Inner Mongolia to Pingxiang city in Guangxi province in nearly NS direction. By using the gravity data collected, we constructed the 2D density model, analyzed the deep structure and tectonic characteristics, reliefs of the intra-crust interfaces and Moho discontinuity and major deep faults along this profile. In addition, we revealed the differences among the different tectonic units in the gravity field, density distribution, undulation of layers and so on. Finally, based on the research in these tectonic units as a whole, we discussed the correlation between the tectonic units along this profile. Our research could provide evidence of the gravity field for the further study of the crustal structure and geodynamics of the continent in central China.

An 1800 km long gravity profile was conducted from Yulin city in Shaanxi province to Pingxiang city in Guangxi province and crossed North China Craton, Qinling Orogen, and Yangtze Craton. By processing and analyzing the data, we constructed the 2D crustal density model and discussed the deep structure, tectonics and faults along the profile. In addition, we discussed the differences between craton, orogen and their coupling belt and interpreted the geological implications of the deep structure along this profile. Our research results can provide evidences in the viewpoint of gravity field to the further study of the crustal structure, tectonic units and geodynamics in this region.

The Panxi region is located in the mid-west of the Emeishan Large Igneous Province, with significant features of geological structures, magmatic activity and strong earthquakes. Many gravity studies have been conducted in this area. However, due to the limitations of gravity data and techniques, some understandings from gravity data interpretation are different from those by other methods. Therefore, it is necessary to do further gravity research in this area. Our gravity data were collected under the control of absolute gravity measurement, along the Yunxian-Huidong and Puer-Qidian profiles crossing the Panxi region between April and May in 2011. Data acquisition was made along roads with two LCR-G gravimeters. GPS synchronized measurement was also conducted with the relative gravity survey, using static measurement method. We applied the following reductions to get the Bouguer gravity anomalies along the two profiles: (1) earth tide reduction, (2) Normal reduction, (3) height reduction, (4) topographic mass reduction and (5) terrain reduction. And then, we built the 2D crustal density structure along both two profiles via 2. 5D gravity modeling. We also analyzed the characteristics of the regional gravity anomalies in the Panxi region, and obtained the apparent density distribution of the lower crust beneath this region through anomaly separation and density mapping. There are obvious differences of Bouguer gravity anomaly characteristics on both sides of the Red River faults zone. In the Yunxian-Huidong profile density model, the average crust density on the western side of the Red River fault zone is lower than those on the eastern side. The faults at depth show a certain degree of Moho undulation, which is likely associated with the tectonic extension in the early Cenozoic. The average crust density of the Puer-Qidian profile between both sides of the Red River fault zone are almost the same, no significant change of the Moho discontinuity. The structural differences between north and south of the Red River fault zone may be related with the distribution of earthquakes. More earthquakes have occurred in the northwestern section, while few happened in the southeast with shallower hypocenters. Seismic profiles and new gravity data suggest that the high gravity anomalies in the eastern section of the Yunxian-Huidong profile is not caused by the Moho uplift. There is a high-density crust-mantle transition layer at the bottom of the lower crust. Previous research drew the similar conclusion by using seismic tomography, which thought that the Panxi region has a 20 km thickness mantle material additional layer at the bottom of the lower crust and the top of upper mantle. In order to further study the density distribution characteristics of the crust-mantle transition layer beneath the Panxi region, we obtained the apparent density distribution of the lower crust in this region through anomaly separation and density mapping. The distribution range of crust-mantle transition layer in the Panxi region is far beyond the scope of the Panxi rift, thus we infer that the transition layer is caused by the magmatic underplating rather than the rift cushion. There are large differences of density structure and Moho relief between the north and south sides of the Red River fault zone, where structure changes along the strike. A high-density crust-mantle transition layer is present at the bottom of the lower crust in the profile of Yunxian-Huidong. Based on the understanding of the density distribution in the lower crust of this region, the transition layer is considered to be caused by the magmatic underplating rather than the rift cushion below the Panxi area.

In this research, the latest field gravity data along a 1010 km-long geophysical profile crossing the Ordos basin, Weihe basin, Middle Qinling orogen and eastern Sichuan basin are collected. Based on this gravity data set, the gravity anomalies in different tectonic units are analyzed, the crustal density model along this profile is constructed, and the undulation and cross difference of density interfaces in crust and the distributional characteristics of faults around this profile are discussed.The research results show that in the Ordos basin, the Bouguer gravity anomalies vary gently. The densities vary mainly in vertical direction. Interfaces are simple and smooth. And there are few faults. In the Weihe basin between the Qinling orogen and the Ordos basin, the Bouguer gravity anomalies are very low. There exists a gravity gradient belt corresponding to the big fault north of the middle Qinling oroge. The Moho interface uplift is about 10 km beneath this area. In the middle Qinling orogen, the Bouguer gravity anomalies vary strongly. Densities change in both lateral and vertical directions. The interfaces in crust are not so clear as those in its two sides. There are a lot of faults, and the Moho interface sinks a little. In the Sichuan basin, the Bouguer gravity anomalies vary smoothly. The density structure varies mainly in vertical direction. Interfaces are more simple and smooth, and there are few faults. These features are similar to those in the Ordos basin.According to our research, there exist obvious differences between the middle Qinling orogen, Ordos basin and Sichuan basin in Bouguer gravity anomalies, crustal density models, undulation of interfaces in crust, and distribution of faults.At last, this study suggests that the North Qinling fault and Ankang fault are the northern and southern contact zones of the middle Qinling orogen in the gravity profile. There exists a "basin-orogen-basin" distinctive tectonic system in the North China craton-middle Qinling orogen-Yangzi craton with its special resent characters of evolution.

The Mongolia arc structural belt has a complicated formation and development history. It is an important boundary that affect the internal tectonic deformation and evolution of China mainland. From the gravity anomalies to study the crustal deformation patterns, to further reveal the continental crust and lithospheric mantle deformation characteristics in the northern part of China, has an important geological and geophysical significance.In order to study the density structures of sources at different depths, we need to separate the gravity anomalies and understand tectonic deformation patterns from the field sources of different depths. First, on the basis of the EGM2008 model, we have the free air gravity anomalies, using the gravity correction approach, calculated Bouguer and Airy gravity anomalies in the Mongolia and its surrounding areas. Then, introduce the Crust 1. 0 crustal model, and establish the reference density model from the surface to the 55 km depth in Mongolia and its surrounding areas. Finally, we extract 6 profiles and determine the hierarchical gravity anomalies in each profile, and make the quantitative analysis on gravity anomaly features of the crust-lithospheric mantle density field source bodies of in Mongolia and its surrounding areas.On the basis of above data and methods, our results include: (1) The gravity anomaly models in Mongolia and its surrounding areas indicate the obvious differences of tectonic deformation between the Hangai dome and Altay Mountains in the western region. There is no area with apparent high-value isostatic gravity anomalies in the Hangai dome. But the high-value regions are concentrated in the southwest of the Altay Mountains. We infer that this feature is related to the new tectonic movement. (2)Based on the reference crustal density model by Crust 1. 0, we have investigated the distributions of lateral inhomogeneous bodies in the crust and upper mantle, and find the lateral density structure is important to forward modeling of the gravityanomalies caused by the Moho relief. (3)We have the comprehensive profiles with density structure from the Crust 1. 0 model. The results indicate that the density feature is consistent with deep crustal deformation and structures of large active faults.From the analysis of the hierarchical gravity anomalies and the reference density models, we suggest a dynamic model that accounts for the deep crustal movement from west to east in Mongolia, in which the force source is not from the squeeze process between the Siberian plate and Eurasian plate, rather related to the northeastward movement of the block in the southwestern Altay Mountains. The formation of strike-slip faults in both north and south of the Hangai Dome is also related to this movement. The deformed interface determined by the Crust 1. 0 model is consistent with the distribution of surface ruptures. There is the correlation between the topography and deep deformation, which consists with the isostatic hypothesis. Therefore, it is a feasible approach to improve gravity inversion using Bouguer gravity anomalies based on the lateral inhomogeneous density model in regions with complex structures. Our results also indicate that the consistency between deep and shallow mass distribution and deformation in the arc-like tectonic deformation zone of Mongolia.

In the earth science study of the Tibetan plateau,there were six main arguments in the foreign scientific circles. They are: the Himalayas is a paradigm of isostasy, the Tibetan plateau crust consists of two vertical superimposed crust; the Yarlung Zangbo river is the suture line between the Indian Ocean plate and Eurasian plate, all the north-south faults in the west of the Tibetan plateau are rift zones, deep material of the Tibetan plateau hinterland escapes to the east, there exists channel flow of the lower crust material in the Tibetan plateau which is related with the occurrence of the Wenchuan M(s)8. 0 earthquake. These series of arguments are widely quoted and followed by Chinese scientists, and several works have been published. However, with the deeper research and further understanding,these arguments should be doubted and re-determined on a scientific concept. New arguments must be put forward based on new cognitions, because science should provide a real picture for the universe. In light of observations, experiments and numerical simulation, six main geoscience arguments of the Tibetan plateau are comprehensively analyzed and re-determined on a scientific concept. The methods used in the study are varied, such as gravity observations and inversion, high-precision artificial source deep seismic sounding, natural source seismic long-period surface wave dispersion inversion, aeromagnetic anomaly measurement, physical experiment modeling, and mathematical simulation. New observations, new arguments and new cognitions allow us to make new collation and stipulation for the six main geosciences arguments of Tibetan plateau and create new theory and models. For example, the Himalayas is not a paradigm of isostasy; the Qinghai-Tibetan plateau crust is extremely thick butdoes not consists of two vertical superimposed crust; the collision of the Indian Ocean and Eurasian plate causes the separation, regulation, movement and coupling responses of deep and shallow material interaction, which form a broad transition zone of collision and compression rather than a simple boundary line like the Yarlung Zangbo river; deep material of the Tibetan plateau hinterland not only escapes to the east but also migrates to the west; the north-south faults in the west of the Tibetan plateau are not rift zones, instead tensional fault zones; the lower crust material in the Tibetan plateau cannot flow, because there are no boundary conditions for flow, matched crust and mantle structures and material property. Based on the ideological recognition for the six main geoscience arguments of the Tibetan plateau, we should realize that Earth science research must quickly get rid of the phenomenon on the basis of the ground derivation or the qualitative inference and fantasy description of surface processes, and consult the response of the deep and shallow material migration behaviors and paths, and make the transition to a half quantitative and quantitative gradually. Earth science research must start from the definition, and be guided by mathematical and physical concepts, in succession on the basis of rational questions, and make the deep process as the leading factor, the data as the foundation, and in the pursuit of scientific truth. The understanding of the earth's ontology should be deepened. Because any geological model or concept must be built on the crust-mantle material dynamic exchange and mechanics of the physics, chemistry, material and energy, and the kinematic and dynamic models must be established by the physics, mathematics and the combination with geology, interaction between deep and shallow subsurface, and the combined static and dynamic processes.

As an important way to reveal the internal structure of the earth, inversion of the density interface is a main subject of gravity research for a long time. Inversion of field data in the frequency domain provides a quick and efficient data analysis method. Combining the advantages of the frequency domain and parabolic density function, this paper presents a processing method for gravity anomaly data of a three-dimensional underground interface using parabolic density-depth function in the frequency domain. The method we used to make forward modeling of the gravity anomaly is based on the algorithm proposed by Parker and Oldenburg which uses constant density contrast. We substituted the constant density function in gravity forward formula for the parabolic density function. Then the Fast Fourier Transform (FFT) was applied to both sides of the equation. We derived the gravity anomaly formula of 3D density interface with parabolic density contrast after calculating the involved integral. To invert the density interface depth, an iterative algorithm was preformed to adjust the interface depth step by step until the difference between the theoretical anomalies and observations reduced to the threshold value. In addition, in order to avoid the divergence of the algorithm which is difficult to avoid for the calculation in the frequency domain, we also added a low-pass filter to the codes. We applied our method to a theoretical model which has 91 X 71 grid data with 10 km interval in x-axis and y-axis, and a complex 3D interface with parabolic density contrast variation in depth. In the synthetic test, we compared the method proposed in this paper with the constant, exponential and binomial functions. Besides the points with acute topography fluctuation, the results show that the inversion using parabolic function provides good and stable estimates of the interface depth of the theoretical model with RMS 0. 02 km, and that the constant density function inversion gives the worst estimate of the theoretical model. According to the comparison, the choice of density parameters is a key factor in interface inversion. For the density of real situation, which varies more rapidly at smaller depth and less rapidly at larger depth, the method provides better approximations to density interface depth. In addition, we applied our method to invert the satellite regional gravity anomaly data with 10 km interval in x-axis and y-axis for the Sichuan-Yunnan region, which has complex geological structures with a large number of major faults, and negative gravity anomalies varying from -540 similar to-90 mGal. We applied the method to invert the Moho depth below this region using reference level 35. 5 km and density contrast -0. 63 g.cm(-3) at the earth surface with attenuation coefficient 0. 0018. We compared the result with receiver function from Li et al. (2014) and other geological information. The differences between results of receiver function and our method at most seismic stations are less than 6 km. Therefore the Moho discontinuation derived from this method shows good correlation with the results of receiver function, other prior geophysical and geological information. Density contrast interface inversion is one of the primary subjects in gravity field research for understanding the earth's interior structure. This work combines the merits of the parabolic density model and the algorithm in the frequency domain, and applies the parabolic density function to the Parker-Oldenburg forward modeling and inversion algorithm. The tests on synthetic data and real data prove the new approach is rapid and effective. By inverting gravity anomaly data using this new approach, we obtained the Moho depth distribution in the Sichuan-Yunnan area, which shows that the Moho interface is shallow in the southeast but deep in the northwest. The Longmen Shan fault zone is a transition zone of the Moho depth ranging from 42 km to 58 km.

在青藏高原的地球科学研究中,国外科技界曾提出过六大论点——喜马拉雅山脉是地壳均衡的典范;青藏高原地壳乃是两个地壳的垂向重叠;雅鲁藏布江是印度洋板块和欧亚板块的缝合带;青藏高原西部的南北走向断裂带全为裂谷带;青藏高原腹地深部物质的向东逃逸;青藏高原下地壳物质通道流以及汶川Ms8.0大地震的发生,这一系列论点确为国人广为引用与跟随,并发表了若干篇论著.然而在不断理解和深化研究的基点上提出了质疑,并基于新的认识提出了新的论点与论据,且在科学理念上给予了重新厘定.因为科学是为宇宙提供真正的写真.

To further understand the deep tectonic background and the magma activities as well as the deep mineralization processes in the Middle-Lower Yangtze metallogenic belt, we construct the 2D crustal density structure model based on the gravity data collected along the Lixin-Yixing geophysical profile in direction of NW-SE. We discuss the deep tectonic framework and mineralization processes on the view points of Moho undulation, characteristics of densities distribution and exist of low-density zones in crust based on the density model we got. The research results show that: the density structure varies strongly beneath the Lixin-Yixing profile; the Moho interface shallows by 3km beneath the Ningwu ore concentration area and shows an uplift form; there exists low-density zone beneath Ningwu ore concentration area. The underplating of magma from upper mantle and MASH ( melting, assimilation, storage and homogenisation) process can provide reasonable explanation for such structure and tectonic framework and the existence of magma and minerals on ground surface. Upwelling of the materials from the lithospheric mantle results not only in the uplift of the Moho interface, but also in the formation of low density zone beneath the Ningwu ore concentration area. Meanwhile, the extensional faults in the brittle upper crust have provided theoretical environment for the upward movement of magmas and the formation of mineral resources.

In this study, we've analyzed some new gravity data obtained from two profiles across the Longmenshan (LMS) Fault system in order to determine the density structure and isostatic state of the crust beneath the Songpan–Ganzi block (SG) and the Sichuan basin (SC). According to our research, Bouguer gravity anomalies along the two profiles range from − 450 mGal in the SG to − 80 mGal in the SC. And density structural models show obvious differences between the SG and the SC. Compared with the SC, the SG has lower average density in the crust, and it has a low-density layer with thickness of 5 km in the middle crust. In the SC area, however, the crustal density increases gradually with depth and there exists no low-density layer in the crust. The Moho interface decreases from 60 km beneath the SG in east Tibet to 40 km beneath the SC. In the LMS region, the topography, Bouguer gravity, and Moho depth change abruptly in a narrow tectonic belt. The crustal isostatic state, which is derived from the Airy compensation model based on the topography, gravity and deep seismic sounding data, indicates that the SG on the northwest side of the LMS is not in an isostatic state, compared with the isostatic crust beneath the SC. The isostatic equilibrium of the crust under the northeast section of the LMS is not achieved as that in the southwest section of the LMS. Based on the research, we infer that the non-homogenous collision between the Tibetan Plateau and the Yangtze Craton has caused the strong variation of the Moho depth and the special isostatic state of the crust in this area.

According to the latest high precision geomagnetic combine with 1 :100000 and 1 :200000 aeromagnetic data across the Southern Ordos Basin-Weihe Basin-Qinling-Daba orogenic belt-Northeast corner of Sichuan Basin, Scilicet the Yulin-Xianyang-Wanyuan-Fulingcombined geophysical profiles, analysed the pattern of magnetic anomaly field, constructed partition and crystalline basement fluctuation characteristics of the study area through data processing and inversion. The result shows that there are obvious differences between different tectonic units. Southern Ordos Basin magnetic anomaly is relatively stable, As it has uplifted and been denudation due to Yanshan movement, crystalline basement is relatively shallow; The Weihe basin and Northeastern of Sichuan Basin have received long-term sedimentation, crystalline basement is relatively deep; The Qinling-Daba orogenic belt magnetic anomaly severe beating, and as it has experienced a long-term collision, estrusion and intracontinental orogenesis, the distribution of stratum and lithology and structure is very unequilibrated, interchanging and migration of substance and energy is present in deep. The results provide very important basis for the further understanding of the deep structures and the pattern of the deep kinematic and kinetic processes and deep resource perspective of the study area.

The August 3, 2014, Ludian, Yunnan, M(s)6.5 earthquake which focal mechanism is the left-lateral slip. The rupture surface of earthquake is the NW direction and almost perpendicular to Zhaotong fault. In our study, we used the 3D gravity inversion approach to inverse 3D density structure, and made a high-quality reference model as initial model with the Crust 1.0 and the newest Moho relief derived by ChinArray project. The 3D density structure shows that the block movement located at the south and north part of Ludian earthquake had been resisted by the Zhaotong fault (ZTF) in the geological time scale, respectively. The resisted ability of north part ZTF is stronger than the south part. Furthermore, we found the significance decrease of gravity field at the Dahaichun (P1) from Oct. 2012 to Jun. 2014. But the gravity change of Jiangdi (P5) measurement point shows the increase tendency. The significant gravity change can't be found at the other points. At last, we give a seismogenic model by the gravity approach. Our results are very important to understand the deep structure of seismogenic region, and also like the key to find the seismic precursor which related to the local gravity change.

In this paper, we have constructed a composition model of the crust beneath the Ordos basin and the Yinshan mountains in north China, with reference to the seismic velocity, heat flow and gravity data measured along the 650-km geophysical profile in the direction of N–S from Yanchuan county in the Ordos basin to Mandula town on the north side of the Yinshan mountains. In order to get this model, we have corrected the crustal physical parameters measured along the profile into the data under the pressure of 600MPa and room temperature (20°C), which we can use to compare with the data measured in laboratory under the same pressure and temperature conditions. Inversion of the geophysical data set to rock compositions indicates that the composition of the crust along the Yanchuan–Mandula profile reveals difference in the Ordos basin and the Yinshan mountains respectively. In general, the composition model of the crust beneath the Yanchuan–Mandula profile generally varies significantly in vertical direction but slightly in lateral direction. The heterogeneity of the distribution of lithologic composition exists mainly in the coupling zone between the Ordos basin and the Yinshan mountains.

The Longmenshan orogenic belt is in a very non-isostatic state, which means its crust is in an unstable state. In this paper, 2-D Finite Element Method is used with viscoelastic model to study the geodynamical mechanism of gravitational isostasy through the profile across the Songpan-Garze block, Longmenshan faults and Sichuan basin. The results show that: (1) The motion mode of deep materials is much changed by the isostatic adjustment. The interaction effects of the India plate collision and the gravity potential energy cause the dynamics of the sub-vertical downward asthenospheric flow at the bottom of the Longmen.shan lithosphere, and lead to the exceptionally steep topography at the eastern Tibetan margin as a result of gravitational buoyancy. (2) The distribution of strain-energy, the rheological structure and other results are calculated numerically, which show that the sections with high risk factors coincide with the areas of the Wenchuan earthquake. The different geophysical structures, as well as the different rheological model on both east and west side of Longmenshan faults zone played important roles in the seismogenic mechanism of the Wenchuan earthquake. (3) We suggest that crustal shortening together with isostatic adjustment, including the rapid erosion-related unloading, is a key component of the geodynamic processes on the eastern Tibetan Plateau margin.

In this study,the density model of the crust beneath the Hetao basin and its adjacent areas was constructed based on the gravity anomalies measured along aprofile crossing the Hetao basin,extending from the north part of Ordos basin to Yinshan orogen.The deep tectonic characteristics and its geodynamic responses were discussed from the viewpoints of the undulation of the Moho and other interfaces in crust,characteristics of earthquakes occurrence and the distribution of mineral resources and energy field,based on the crustal density model obtained in this study.The research results suggest that,there exist obvious differences in crustal density structure between the Hetao basin,Ordos basin and Yinshan orogen.Beneath the Hetao basin,the crystalline basement is as deep as 7~8km,and the Moho interface there is 3~4km shallower than its two sides.Upwelling of the materials from the lithospheric mantle results not only in the uplift of the Moho interface,but also in the formation of higher density zone in the ductile lower crust beneath the Hetao basin.Meanwhile,the deep faults in the brittle upper crust have provided good environment for the occurrence of earthquakes and formation of the mineral resources.In addition,the distributional characteristics of earthquakes imply that the coupling zone between the Ordos basin and the Yinshan orogen consists of both the Hetao basin and the south part of the Yinshan orogen.