The Early Precambrian granitic gneiss are widely distributed in Tonghua in southeast Jilin Province. The lithological assemblages, ages and petrogenesis of these granitic gneiss are informative to the formation and evolution of the early crust in the northeastern margin of the North China craton. Based on the systematic petrology, zircon U-Pb chronology, element and Lu-Hf isotopic geochemistry results, we divided these granitic gneisses into high silicon group and low silicon group according to their SiO₂ contents. The former is mainly composed of monzogranite gneisses, trondhjemite gneisses and tonalite gneisses, and the magmatic precursors was emplaced at 2 549-2 557 Ma. While the latter is composed of quartz-monzonitic diorite gneisses and granodiorites gneisses, and their protolith may be formed at 2 534-2 552 Ma. The both groups contain zircons captured at ca. 2 600 Ma, and suffered from the metamorphism for ca. 2 500 Ma. The geochemical data show that the low silicon group is rich in MgO, CaO and Na₂O, belonging to the high-medium K calc-alkaline series, and has the feature of higher contents of LREE, but lower contents of HREE and HFSE. In contrast, the high silicon group has the lower MgO and CaO, and exhibit a stronger fractionation between the light and heavy rare earth elements, and the elements of Nb, Ta, P, Ti are depleted. The two groups show the weak positive or negative Eu anomalies. In combination with the regional geological data in this study, we believe that the two groups were derived from the same source, and their formation may be related to the ocean plate subduction through a partial melting of the crust caused by the magma underplating. Moreover, the two groups have similar ε_Hf(t) values (2.72 to 7.95) and model age (2.86 to 2.55 Ga), which suggests that a crustal growth occurred in the study area in the Late Neoarchean. According to the research progress of metamorphic volcanic rocks in the region, we consider that the granitic gneisses in Tonghua may be formed at an active continental margin.

Water-transgressive sand is defined as the rock or unconsolidated sediments,which are eroded, eluted, transported and so on during the process of transgressive, forming the sedimentary characteristics that are obviously different from the background sand bodies in the original sedimentary environment, and shows obvious diachronism. Water-transgressive sand plays an important role in hydrocarbon migration and storage, prediction of crude oil properties, and oil and gas exploration and development. The discovery of water-transgressive sand improves the theory of sequence stratigraphy. The authors classified the water-transgressive sand based on four aspects:the nature of sand body, the source of sand body, the environment of background sand body and the tectonic development conditions, and summarized the representative forming mechanism as follows:the formation response model, the transgressive delta model, the transgression-regression model, the hydrodynamic model, the incised valley model, and the tidal ridge model. Based on the traditional sedimentology, some scholars have also applied the comparatively unique methods,such as hydrodynamics, ichnology and unconformity recognition,to study the water-transgressive sand in recent years. The future research on water-transgressive sand will no longer be confined to marine sand bodies, more sophisticated methods will be used to conduct a more in-depth study on water-transgressive sand.

Fluid inclusion analysis is an effective method in the research of oil and gas migration, accumulation, and charging. In this study, the accumulation-forming stage and time of the petroleum reservoir in the Bachu-Maigaiti area locating in Tarim basin were determined on the basis of fluorescence microscope observation and measurement of salinity and temperature regarding the fifty-three samples from eight wells by fluid inclusion analysis, in combination with the burial and thermal histories. The results indicate that 4 acts of 2 hydrocarbon migration and accumulation periods occurred in Paleozoic. The first period is the early accumulation stage during the Late Hercynian period, and can be further divided into two episodes, i.e., Late Carboniferous-Early Permian of (309.4-289.2) Ma and Late Permian-Early Triassic of (262.9-241.2) Ma; The second period is the Late Himalayan period that can be divided into Late Neogene of (6.3-4.2)Ma and Early Quaternary of (2.3-1.6) Ma, and during which the high maturity hydrocarbon and natural gas primarily filled. According to the history of tectonic evolution of the basin, the two hydrocarbon migration and accumulation events were originally triggered by the late Hercynian and Late Himalaya tectonic movements, and then the evolution of the hydrocarbon source rocks was ended by the Indosinian-Yanshanian tectonic uplift, all of which jointly constituted the two hydrocarbon accumulation periods.

Based on the core observation, thin section identification, scanning electronic imaging, and petro-physical property and other technical methods, the basic reservoir characteristics of medium-deep strata of beach-bar sandstones were investigated in the upper part of Es₄ (Es₄^s) in the Boxing sag, Dongying depression. The results indicate that the reservoirs are mainly characterized by low porosity and low permeability, and the reservoir spaces are mainly of primary and secondary pores. The formation mechanism of high-quality reservoirs is mainly consist of sedimentation, stratigraphic overpressure, hydrocarbon injection, acid dissolution,and chlorite grain coating. The reservoirs of both bar body and beach edge sub-facies that are far from mudstones are well sorted with strong anti-compacting capacity. Abundant primary and secondary porosities are developed in the medium-deep strata because of the modifications caused by acid dissolution and hydrocarbon filling. These reservoirs are protected by both stratigraphic overpressure and chlorite grain coating, and therefore become effective high-quality reservoirs. The lithofacies of both bar bodies and beach edge sub-facies adjacent to mudstones are typically characterized by the extensive carbonate cementation, which results in the extremely physical properties and invalid reservoir quality. The lithofacies of both bar edge and beach mat sub-facies were deposited under the poor depositional conditions with high contents of matrix. The reservoirs were dominated by compaction and micritic carbonate cementation with weak acidic dissolution. The present physical properties are extremely poor and characterized by invalid reservoirs from shallow to deep strata. The high-quality reservoirs of beach-bar sandstones are located at the central section of thick bar bodies and beach edges.

The Guantao Formation (Neogene) is the most important reservoir in the Kongdian oilfield with fluvial facies developed. The complex distribution characteristics and connectivity of the fluvial sand bodies cause a complex relationship between oil and water in the process of water flooding, and which, in turn, control the formation and distribution of the remaining oil. Through the detailed study of the core and logging data, the sedimentary model of the Guantao Ⅲ Member in the study area was determined,and a detailed characterization of the reservoir architecture was completed. On the analysis of the reservoir architecture characteristics, the distribution types of remaining oil were summarized. The authors believe that the third member of Guantao Formation is a braided river with the elements of braided channel, central bar,and levee developed. The central bar is the most important oil and gas enrichment unit in the braided river sediments, and the distribution form of remaining oil can be influenced by water injection. Three types of the silting layers of muddy, calcium and silty exist in the strata. The central bar can be divided into four parts including bar head, bar main part, bar tail, and bar limbs. The silting layer in bar head is poorly preserved; The silting layer in bar main part is preserved relatively complete in a nearly horizontal shape; The silting layer with a low angle in bar tail is preserved relatively well; The silting layer in bar limb is influenced by slope, preserved well in a steepslope but poor in a gentle slope. The remaining oil in a central bar of anatomy area is mainly concentrated in the middle part of the left bar limb and the bar tail that is blocked by a silting layer.

The Yanchang Formation is one of the most promising area for shale gas exploration in the Ordos basin. The Chang 7 Member of the Yanchang Formation in the eastern Ordos basin was selected as the research object. Based on the nitrogen isothermal adsorption, field emission scanning electron microscopy (FESEM) in combination with the laboratory tests on mineralogy, maturity and TOC, the pore types, structures as well as their controlling factors were analyzed respectively. As shown in the results, the pore structure of Chang 7 Member shale gas reservoir is complex, and can be divided into 2 types according to the adsorption loop morphology. TypeⅠloops mainly correspond to the parallel plate-like holes or micro-cracks with a pore structure of 2.6-4.2 nm in diameter or in a wedge structure, and can be classified into clay-mineral intergranular pores, organic-matrix-like pores, and matrix microcracks; typeⅡloops are mainly open-ended cylindrical boreholes in 2.3-3.1 nm, 3.5-3.8 nm, and 4.3-5.2 nm, including organic pores and residual intergranular pores. Mesopores and micropores are major contributors to total volume and specific surface area,which is controlled mainly by TOC with a positive correlation with both total volume and specific surface area. Neither R_o nor mineral contents show any influences on the pore structure; however, clay minerals contribute a lot to the volume of micropores, which is supported by the relatively positive correlation between illite contents and the total volume and specific surface area.

As a result of a complex diagenetic evolution, a reservoir with low porosity and ultra-low permeability exists in the ultra-deep sandstones of Bashijiqike Formation of Cretaceous in the Keshen area of Kuqa depression, Tarim basin. This paper presents an overview of the types and origin of the sandstone porosity and the controlling factors. Based on the identification of many cast and fluorometric slices by using the field emission scanning electron microscope and confocal microscope, eight types of pores and two kinds of fissures in this sandstone reservoir are recognized according to their shape, scale and origin. The pores are dominated by the secondary pores, which is the result of the following complex geological process:1) The sandstone was buried shallow for a long time in the early stage, so no porosity-decreasing effect occurred during the weak compaction; 2) The Early Cementation saved some primary intergranular pores; 3) The porosity was further decreased by the effect of the tectonic compression in the late burial process;4) The secondary pores were mainly formed by the later dissolution, but which didn't evidently change the porosity of the sandstone reservoir.

To accurately evaluate the vertical sealing ability of the faults in caprock, based on the experiment of verifying the influence of the rock anisotropy and the mechanical relation of the displacement pressure of the fault rock and the reservoir rock in different directions, we improved the pressure-difference method to evaluate the fault sealing ability,and further analyzed the vertical sealing ability of the main faults F_np5-3 and F_np5-5 in 5th structure of Nanpu sag in the Bohai Bay basin, in combination with the differences in diagenetic time of different rocks, as well as the influence of the rock anisotropy on displacement pressure. The results indicate that:there is a low limit of displacement pressure difference between the fault rock and the reservoir rock, and only if the displacement pressure of the fault rock is larger than that of the reservoir rock,and the difference between the above two is larger than or equal to the low limit, then the faults seal vertically. From this, it is determined that the low limit of the reverse fault F_np5-3 is 0.221 MPa, and the low limit of the forward fault F_np5-5 is 0.311 MPa. Influenced by the accumulation of oil-gas and the characteristics of the fault internal structure, reverse faults are more likely to seal than forward faults. This is coincided well with the pattern of oil-gas accumulation; while the evaluation results obtained by the previous method without considering the above factors are inconsistent with the actual drilling oil-gas results. The improved method is reasonable and feasible for a comprehensive evaluation of the fault vertical sealing ability.

In a preliminary study, we found an amount of HREE in Zoujiashan uranium deposit as associated ores. To recycle these rare resources and explore their origin are very important. The basic work is to find out the characteristics of HREE associated in Zoujiashan uranium deposit. To do so, we used the electron probe micro-analyzer (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to analyze their occurrence characteristics. The results show that the deposit contains mainly monazite, roentgenite, and xenotime. The LREE/HREE ratios of the monazite and roentgenite are high, a LREE enrichment type; While the LREE/HREE ratio of the xenotime is low, a HREE enrichment type. The minerals of uranium and thorium including pitchblende, brannerite, uranothorite, coffinite, thorite and zircon are of the type of HREE enrichment. Their total REE (∑REE+Y) is high with a range of (3 805.78-65 307.00)×10^-6, their value of LREE/HREE is low with a range of 0.01-0.80, and the average is at 0.29. The other associated minerals,including apatite and potassium feldspar,are of the LREE enrichment type, while the fluorite is of the both types. Both LREE and HREE enrichment in the illite and pyrite are not significant. The HREE exists mainly in the form of isomorphism in the minerals of xenotime, uranium, and thorium, and a small amount of HREE is in the associated minerals.

The Gejiu tin polymetallic deposit is located in the west of the southeastern Yunnan tin ore belt, and is one of the largest tin polymetallic deposits in the world. As the main ore minerals in the Gejiu tin-polymetallic deposit,the mineral chemical characteristics of cassiterite have a great implication to the ore genesis. In this research, we studied the internal structure and the mineral chemical characteristics of cassiterites out of six types of ores in the Gejiu tin-polymetallic using the scanning electron microscopy and electron probe microscope analyzer. The results of scanning electron microscopy show that except the interlayer oxidation broken ore type cassiterites,the zonal structure is clearly developed within cassiterites. The results of electron probe microscope analyzer (EPMA) show that the variation range of the mass fraction of SnO₂ is 97.700%-101.728%, and the mass fractions of Ta₂O₅, FeO, ZrO₂ and HfO₂ are high, which indicates that these cassiterites may be precipitated in a high temperature environment. The value of (Fe+Mn)/(Nb+Ta) shows that the different types of cassiterites have the characteristics of hydrothermal cassiterites. Very low mass fractions of Nb₂O₅ and MnO in different types of cassiterites suggest that the ore-forming fluid may be derived from the high-fractionated granitic magma. The mass fractions of Na, Ta indicate that the mineralization occurred in an acid to weak acid environment. The gradually decreased In₂O₃ in different ores (including sulfide, skarn, tourmaline veinlet belt, tin-bearing dolomite, and interlayer oxidation types of ores) indicates that the ore forming temperature and pressure have decreased gradually. However, the average mass fractions of In₂O₃ in greisen type need further study. The change of the physicochemical conditions of magma hydrothermal fluid during the formation of cassiterite resulted in the formation of its internal zonal structure. The electron probe data shows that the chemical composition in the zonal structure of cassiterite is "serrated", indicating that the mineralization occurred in turbulence, so the cassiterite deposits have multi-stage characteristics.

The Baoshan Cu-Pb-Zn polymetallic deposit is located in the central Nanling mineralization zone, and is an important type of deposit in the Nanling polymetallic deposit belt. The Baoshan Cu-Pb-Zn polymetallic deposit shows the horizontal mineralized zoning clearly. Its zonation is comprised of Cu -Mo belt and Pb-Zn-Ag belt at the mining area from the middle to the periphery. In this research, the mineralogical study and electronic detection tests on the garnets, diopsides, pyrites, and sphalerites in the Baoshan Cu-Pb-Zn polymetallic deposits were conducted, and the mineralization was summarized as the skarn, retrograde and oxide, and sulphide stages. The garnet endmembers are mainly andradite(23.48%-90.39%)and followed by grossular(5.81%-71.27%);Pyroxenes are mainly diopsides(Di_61-95). The mineral characteristics of garnet and diopside in the skarn are similar to those in typical Cu skarn all over the world. The composition of the pyrite and sphalerite in the sulfides of the Baoshan Cu-Pb-Zn polymetallic deposit indicates that the sulfides in the Baoshan Cu-Pb-Zn polymetallic deposits were from a magmatic hydrothermal source, and is characterized by a higher temperature in the northeast than in the southwest.

Tuquan-Keerqin Youyizhongqi of Inner Mongolia is located in the central and southern Da Hinggan Range, where the Mesozoic magmatic activity was frequent. The rocks are mainly composed of granodiorite, syenite, monzonitic granite, and granite porphyry etc. We studied the Mesozoic granites in the whole area to obtain the related geological data,tested the LA-ICP-MS zircon U-Pb age,divided the different Mesozoic magmatism periods on the basis of the predecessors' data,and then discussed the geological significance of the different granites in this area. Several samples of the three magmatic intrusive rocks from this region were dated by the LA-ICP-MS technique. The result indicates that the granodiorite of Mengentaolegai pluton was emplaced at (241.2±2.8) Ma, the syenite in the southern Duerji was emplaced at (148.2±1.0) Ma, the monzonitic granite of Baogetu pluton was emplaced at (226.0±1.1) Ma, and the granite porphyry of the Majiatun pluton was emplaced at (124.6±1.1) Ma, corresponding to the ages of the volcanic rocks respectively. Combining with the previous and adjacent geological data, we divided the magmatic activity into three periods:Middle-Late Triassic, Late Jurassic, and Early Cretaceous. We conclude that the Middle-Late Triassic granites may be the product of the post-orogenic lithospheric extension of the Paleo-Asian Ocean closure, and the formation of the Late Jurassic granites may be related to the Mongol-Okhotsk Ocean closure; while the Early Cretaceous granites might reflect the extensional tectonic setting.

Retaining structures are easily influenced by the soil frost heave in cold regions. The excessive horizontal frost heaving force can easily cause the supported structures to deform, crack, break, or even dump, which is a serious threat to the security and stability of engineering, and therefore it is of great significance to study the cold retaining structure horizontal frost heaving force. The main study and research on the horizontal frost heaving force focus on the influence factors, distribution patterns, force value, calculation method, and prevention measures at home and abroad. The results show that the strength of horizontal frost heaving force and its distribution pattern depend on soil type, soil particle size, dispersion, mineral composition, soil temperature, moisture content, water supplies, and supporting structures. There are many different distribution patterns and calculation methods. Each calculation formula has its own restriction. In actual engineering, to weaken the influence of the horizontal frost heaving force, the methods usually used are as follows:fill with soil, enhance thermal insulation, waterproof and drainage, using physical and chemical reagents, or other more comprehensive measures.

In order to calculate settlement of soft ground reasonably, the paper focuses on the secondary consolidation characteristics and influencing factors of soft soil. In this study, a series of consolidation and compression tests were conducted on the Yitong soft soil. The characteristics of consolidation and secondary consolidation of Yitong soft soil were analyzed with a graded loading method. The research results showed that there is a good linear correlation existed between the strain rate and time in double logarithmic coordinates:With the increase of load p, the secondary consolidation coefficient C_a increased rapidly, and then decreased gradually to a stable value; There is a linear correlation between the secondary consolidation coefficient C_a and the compression index C_c, and C_a decreased logarithmically with time. The ratio of C_a/C_c is between 0.030 and 0.043. The minimum of C_a is about 72.3% of the maximum. These data provide some references to deformation prediction of soft ground in Yitong area.

The establishment of the evaluation index system of a well field of Karst water is explored in this paper by taking the well field of Niangziguan spring as an example. On the basis of fully consideration of Niangziguan spring resources characteristics, combination with the DPSIR (driver-pressure-state-impact-response) and the European model for Karst aquifer vulnerability index framework, the evaluation index for selection was build. Firstly, the method combining expert consultation with the actual situation was selected, according to the relevant indicators data from 2011 to 2015, all the alternative indicators were determined. Then, the principal component analysis method was used to select the final index, and the rationality of the chosen indexes were verified by principal component analysis. Finally, four aspects including social, economic, environmental and policy were determined, and the water supply risk evaluation index system of the well feild of Niangziguan spring was composed of the 19 indexes of the 5 criteria layers. After verification, the chosen indexes have rationality and applicability, which can effectively identify the risk of well field.

The mineral springs in the Yaoquan Mountain have been the important resource for the tourism and therapy in the Wuda-Lianchi geological resort, and attracted much more research in recent years, but no one is for the microbial diversity of the mineral spring. Based on the previous environmental hydrogeology of this area, the sampling and analysis of the springs in the typical seasons were undertaken,and further the molecular biology work for the microbial diversity was conducted by the PCR-DGGE technique. The results showed that there was a distinct micro-diversity in the study area,and the micro-statistical parameters were greatly different in different seasons. The micro-diversity changed a lot at various spatial locations in summer, but generally consistent at the same location, showing that microorganisms of the springs responded well to the geological settings and environmental conditions. There were clear differences for the statistical parameter of microbes at different spatial locations in winter, but the other parameters changed little. This study is scientifically valuable for the insight of the springs formation at a micro-level in Wuda-Lianchi.

Choosing suitable types of facilities according to the topography and geological conditions is one of the important parts during the construction of sponge city. This study is based on one part of a sponge airport under construction. After a wide collection of the geological and hydrogeological data, the authors analyzed the influence factors of the construction of sponge city. From the suitability of surface, vadose zone and phreatic aquifer, seven influence factors were chosen to be the evaluation indexes of geologic suitability of sponge city construction, including terrain slop, surface permeability, aeration zone thickness, aeration zone permeability, aeration zone clay thickness, aquifer permeability and aquifer thickness. The analytic hierarchy process was used to assign the weight of each influence factor. Finally, ArcGIS was used to stack the scores through weighting by the score of each influence factor graded according to the national standard or the situation in the study area. According to the scores of each rating region, the authors suggested the suitable facility types of sponge city. The results show that geological conditions and hydrogeological conditions have a significant impact on the infiltration, underground storage, and transmission of rainwater. The geological and hydrogeological conditions should be made a full use in the construction of sponge cities to design the facility types and construction schemes of low impact development (LID). The permeability and the thickness of aeration zone are the most important factors for the geologic suitability of sponge city construction; and both of them determine the suitability of LID facilities with rainwater infiltration as the main function.

Land subsidence in Beijing has been developing rapidly since it was discoverd in the 1960s. Uneven ground deformation can destory buildings, and urban infrastructures such as underground pipelines,threatening urban security. In order to analyze the characteristics and the evolution trend of land subsidence in Beijing plain, 27 scenes of Radarsat-2 data from 2011 to 2014 were collected, and the interference point target analysis (IPTA) technology was performed, to obtain the time series land subsidence information. On this basis, four land subsidence areas were selected representatively, and multi-scale evolution characteristics of land subsidence were analyzed through Morlet wavelet tranform respectively. The results show that the maximum subsidence rate is 162.70 mm/a while the average rate is 50.08 mm/a, and subsidence rates are quite different among these areas in spatial distribution. Moreover, the wavelet transforms analysis indicates that the land subsidence present obvious local periodic variation characteristics in the time domain. In particular, at the time scale of 28 T(1 T represents a perod of 24 d), there is a time period of about 13.3 months, with different unstable oscillation periods in different positions.

Image processing method is commonly used in analyzing the experimental data obtained from dye tracer experiments. The authors contrasted the image processing method with a conventional sampling method to monitor the precision and plume accuracy in using brilliant blue as the tracer. We quantitatively calculated the mass storage in the sand boxes by the Matlab programs. The results showed that the monitoring precision and the plume accuracy raised by one order of magnitude and about 3% respectively when we used the image processing method,and the plume accuracy raised by 17% under the heterogeneous conditions set by the experiment. The storage mass was almost the same as the one using the Matlab program. When the grid number was 13.69 million, the minimum error was 0.5%. Generally, the image processing method provides a high-accuracy and high-resolution way to acquire and dispose the picture to describe the migration process in the heterogeneous media more subtly.

The Songhua River is one of the seven major rivers in China. The study of the spatial and temporal distribution characteristics of heavy metal elements in the sediment is of great significance for the water environment control of the basin. In this study, an effort is made to clarify the distribution characteristics of As, Hg, Cr, Cd and Pb in the surface sediments from the Songhua River (Hadashan-Songhua Lake region), and to evaluate the status of the heavy metal pollution using the index of geo-accumulation (I_geo). The I_geo values reveal that almost all the sediments are free from pollution by As, Cr and Pb; In contrast, most of the sediments are contaminated with Cd and Hg, especially Hg. The Hg contamination level is extremely high in individual stretch of the river. Compared with the situation of ten years ago, the pollutions of these heavy metals have been greatly reduced, except that the Hg pollution is still very serious in the region of Jilin City. The spatial distribution characteristics of polluted sediments indicate that the region of Jilin City may be significantly polluted by the heavy metals from industrial and agricultural wastewater.

Chuxiong basin is the largest petroleum-bearing basin in the Yunnan-Guizhou-Guangxi area, but its progress of oil and gas exploration is slow. The key issue is the unclear structure of the basement and sedimentary caprock. Two parallel exploration profiles were obtained based on the high precision gravity, magnetic and electrical data,and the basement characteristics and stratigraphic structure were figured out hereupon. The comprehensive exploration results show that the maximum burial depth of bottom boundary is 7 km in the Upper Triassic in the western Chuxiong basin. The overall trend of Chuxiong basin is north-west, and the maximum depth of the crystallization basement is 9 km between the Pingchuan-Yunnanyi-Honghe and the Menghu-Shezi faults. The largest magnetic basement sag in Chuxiong basin exists between Dayao County and Nanhua County, with an area of 1 200 km².

Modelling and identification of subsurface electrical anisotropy has always been a hot topic in the geophysical community. This paper presents a 3D anisotropic forward modelling algorithm using an adaptive finite-element method based on unstructured grids. Based on the existing research, we analyzed the typical anisotropic models, and studied the characteristics of the apparent resistivity related to the electrical anisotropic media and the identification of underground electrical anisotropy. Considering the existence of anisotropic paradox, we applied the circular direct current (DC) scanning measurement. The ratio of the principal resistivity affects the ratio of the major axis to the minor axis in the elliptical polar apparent resistivity curve, and the rotation direction of the principal resistivity changes the shape of the polar curve. The adaptive finite-element code is checked for accuracy against 1D semi-analytical solutions for an arbitrary anisotropic earth. The algorithm and results of our numerical experiments provide a technical support to the processing and interpretation of DC resistivity data.

It's difficult to estimate a seismic reflector dip at discontinuities. Many seismic attributes such as reflector dip change fast at faults, geological boundaries and so on. To overcome this problem, we explored an adaptive weighted generalized inverse vector direction filter to smooth the gradient vector field to estimate a local seismic reflector dip. The method is as below:at first, to compute the gradient vector field by a modified finite-difference method; and then to set the reference direction to vertical downward and invert the opposite vectors to the reference direction; at last, to estimate the seismic reflector dip by the adaptive weighted generalized inverse vector direction filter. This method can estimate a seismic reflector dip robustly and efficiently with high-resolution at discontinuities, while the conventional methods may fail. Both of the synthetic and real data examples demonstrated the effectiveness and efficiency of our method for estimating seismic reflector dips with high-resolution.

When using the grid methods, such as the finite difference method for solving the eikonal equation satisfied by seismic traveltimes, the traveltimes obtained at the adjacent grid points may not have the smoothness needed for computing ray trajectories. This is because of the discretization of the velocity model by grids. To solve this problem, some researchers proposed a backward gradient scheme based on a B-spline interpolation. However, the ray trajectories calculated by the B-spline interpolation scheme will have large errors when the velocity changes abruptly in some model region. Aiming at this problem, instead of the B-splines, we first utilized the Chebyshev polynomials, which are optimal for solving the zero deviation and the least square problem, to obtain the formulas that can optimally approximate the grid point traveltimes resulted from the finite different solution of the eikonal equation. Then, we used a computation procedure which is similar to that used in the B-spline scheme for obtaining smooth ray trajectories. The numerical test showed that the use of Chebyshev polynomials for approximating traveltimes led to smooth ray trajectories of multiply reflected waves with high accuracy. It should be investigated further in the future work.

Compared with the integer derivative, the fractional differential operator can describe a complex mechanical and physical process with historical dependence and spatial global correlation more succinctly. But the computational complexity and the storage capacity of the numerical simulation of fractional wave equations will increase, especially for the simulation of long or large computational domains. In this paper, three kinds of calculation methods are given:global memory method, short-term memory method, and adaptive memory method. These three methods were applied to the simulation of the fractional-order wave propagation equations in a vicious fluid-saturated vicious two-phase VTI medium. Comparing the simulation accuracy, calculation time and memory usage of the three methods, we found that although the short-term memory method could adjust the calculation time and memory by setting the short-term memory length, the shorter the short-term memory length, the worse the accuracy. On the premise of ensuring accuracy, the adaptive memory method is a compromise between the short-term memory and the global memory methods in terms of calculation time and memory occupation. In the process of forward modeling, not only should the model be closer to the actual underground media, but also the selected numerical algorithm needs to balance the calculation time, the calculated storage capacity, and the precision. This method provides a reference for the follow-up forward modeling and the development of the new fractional numerical algorithm.

Since the elastic reverse time migration (RTM) is more representative to the actual situation, and the converted-wave RTM results have high resolution, the study of elastic RTM draws more and more attention in the recent years. Because multicomponent data is required by the elastic RTM method, and its wavefield contains both P-and S-waves, before imaging we need to separate the P-waves from S-waves so as to avoid the crosstalk. Combining with the vector-based excitation amplitude imaging condition, we applied the wavefield decomposition method based on the decoupled propagation to the elastic RTM and analyzed its application in the isotropic and vertically transversely isotropic (VTI) media. The results demonstrated that the method perfectly decomposed P-and S-waves in the isotropic media and preserved the vector information also. Although there were some small residuals in the separated wavefield for the VTI media, this residual did not generate obvious artifacts in the RTM results. Therefore, this wavefield decomposition method can be applied in the elastic RTM for an isotropic and VTI media. This method is realized in time-space domain. The separation of P-and S-waves can be directly separated during the wavefield propagation conveniently and efficiently. Compared with the elastic RTM using Helmholtz decomposition, this method avoids the problem of polarity reversal in the PS images. The migration results of the complex Hess VTI model showed that the high-velocity rock mass and a fault were clearly imaged, and even two low-velocity thin interlayers were well imaged. This suggests that the method is better adaptive to a complex model. The PS images can present a relative clear image of an anisotropic body. It demonstrates that the anisotropic elastic RTM can be used to image some subsurface structures better than the conventional RTM.

The frequency-magnitude distribution (FMD) is one of the most important empirical equations. The parameter b, presenting the characteristics of foreshocks and aftershocks, is often used in the tectonics and seismic hazard assessment. Earthquakes frequently occurred in Jinzhou fault zone before. Since the Haicheng M_s 7.3 earthquake occurred in 1975, the Haichenghe-Dayanghe fault interlaced with the Jinzhou fault has been active. An earthquake with M_s 5.6 occurred in Xiuyan in the year of 1999, and Gaizhou has high seismic activities recently as well. In this study, the spatial distribution of b-values were used to detect current stress state of Haicheng region. Relocated earthquake data by double-difference (DD) algorithm can significantly improve the location precision, although suffer from the degeneration of data completeness. We collected arrival-time data recorded by the seismic network, and used the DD method from 1981 to 2005. The spatial distribution of b-values from routine catalogue and data after using DD method were compared and analyzed,which revealed that DD data can be used for b-value calculation and has higher accuracy when the earthquakes clustered. We got the vertical and horizontal variation of b-values using gridding techniques with DD data in Haicheng and Xiuyan area. Our results revealed that the b-values were varied spatial significantly, ranging from 0.6 to 1.8, and decreased with depth. The Xiuyan and Gaizhou area with low b-values may indicate the area most likely seismogenic for future large earthquakes. The Hunhe area and the southeast part of Haichenghe-dayanghe fault have high b-values,indicating a low opportunity for seismic hazard. Near the intersection of Jinzhou and Haichenghe-Dayanghe faults, the b-value is closed to 1.0, such a stable stress suggests a low probability of future large earthquakes.

The photometric behavior of the moon's surface describes how the reflected solar radiation varies with incidence, emission, and solar phase angles, depending on the physical and chemical properties of the lunar soils, such as the particle size, the shape, the porosity, and the mineralogical composition. In order to analyze the lunar photometric behavior and understand the reason of regional differences, we retrieved the photometric parameters of Hapke model using the moon mineralogy mapper data in the Apollo 16 landing area. The influence of the Hapke model photometric parameters on the bidirectional reflectance was analyzed. The inversion results showed that the parameter b and h_S of the model varied slightly, while the parameter w of the model changed to certain extent. The difference of reflectance is mainly caused by the w in the study area. The mineral particles in the study area in lunar soil forward scattering dominates. The soil structure and particle size are overall similar, but at least one factor of the porosity, the weathering layer filling state, the surface roughness and other factors is different.