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Objective Thrust faults and their associated folds are important structures of continental tectonic deformation, widely distributed at plate boundaries and within plates. The activity of these thrust faults can trigger severe seismic disasters, such as the 1999 Chi-Chi earthquake in Taiwan and the 2008 Wenchuan earthquake. However, research on surface ruptures and associated disasters caused by thrust faulting is relatively limited, mainly due to the complexity of their fault propagation processes. Studying thrust faults and their associated folds could enhance the capability of seismic hazard risk assessment and better predict earthquakes and potential secondary disasters. Methods This paper first introduces the meanings of fold-related faults and fold scarps and explains the impacts of surface uplift and lateral extension deformations on topography. Taking the Tian Shan active fold zone as an example, the paper focuses on analyzing the structural characteristics and landform deformation patterns of the Hejing thrust-and-fold belt in the northern margin of the Yanchi Basin and the Mingyaole anticline in the southern piedmont of the Tian Shan. It also discusses various types of structures, such as thrust faults, fold-related faults (flexural faults, flexural slip faults, and conjugate shear faults), and their effects on landforms. Based on this, the paper explores the relationship between the growth process of active folds and the formation of seismic geological disasters. Results and Conclusion It is believed that in a compressive tectonic environment, the growth of active folds and the formation of fault-related folds cause building displacement, tilting, and damage, thereby generating geological disasters. In particular, it emphasizes that the tilting of the ground on both sides and the footwall of active anticlines during the process of crustal shortening, vertical uplift, and lateral expansion poses a threat to the safe operation of major engineering structures. Simultaneously, the bending deformation caused by regional crustal shortening presents potential seismic risks and triggers geological hazards for significant linear engineering projects spanning active anticlines, warranting attention.

Under the action of the Earth’s inner dynamics, the lithosphere shapes different types of the Earth’s surface, and the crustal stress state and its dynamic change law are captured by the comprehensive observation technology of drilling crustal activity. It is an important way for human beings to understand the internal dynamic process of the Earth and study the mechanism of inner dynamic geological hazards. The contribution of developed countries such as Japan, the USA, and the IODP International Cooperative Research Program to the development of integrated borehole crustal observation technology is summarized in this paper. The paper also systematically reviews the development history and present situation of borehole strain observation technology and borehole strain observation instrument in China. Especially since the 13th Five-Year, under the background of the national strategy of deep-sea exploration, the China Geological Survey Bureau (CGS), the China Earthquake Administration, and other systems have successively carried out research and development of the integrated geophysics observation system in wells, and have been put into use in integrated land and sea observation stations. The Institute of Geomechanics has successfully developed an integrated geophysics observation system for crustal activity using the key techniques of system integration. The system has a variety of strain, tilt, seismic, geomagnetic, geothermal, pore pressure, other sensors, and 16 components capable of observing crustal deformation, stress, strain, tilt, earthquake, and their induced geodynamic changes in the lithosphere, such as geotemperature, hydrology, geoelectricity, geomagnetism, etc. It has been put into use in Shandan (installed depth 253 m) and Pingwu (WFSD-4, 1600 m) observatories in Gansu and Sichuan provinces and has achieved initial results. It is a milestone for our comprehensive crustal activity observation technology to break through the 3000-meter-deep well in the future. It can provide vital information for geodynamics research, safe exploitation of deep mineral and geothermal resources, and prediction of internal dynamic geological hazards. At the same time, based on the national strategy of deep-sea exploration in the 14th Five-year, the future development direction of integrated observation system of deep-well crustal activity is pointed out.

Monitoring data over the years have shown that seasonal rainfall and reservoir level changes have always accompanied the accelerated deformation of the Xigouwan landslide, which makes it difficult to identify the dominant triggering factors of landslide deformation and poses a challenge to risk analysis. Given this, this paper analyzed the correlation between the daily deformation rate of the active and inactive areas in the Xigouwan landslide and rainfall, reservoir level, and the change rate of reservoir level by applying the attribute reduction algorithm of the neighborhood rough set model. The calculation results showed that the deformation in the active area was mainly affected by the rainfall in the past seven days. It was also related to the short-term change rate of reservoir water level in some ways. The weak deformation in the inactive area was related to the change rate of reservoir water level in the past three days. Then, based on the landslide deformation characteristics, it was further obtained that the average rainfall in the past seven days inducing severe deformation in the active area was about 20 mm. The decline of the reservoir water level influenced its deformation, but the effect was small. The reservoir level change affected the weak deformation in the inactive area with negligible influence, while the weak deformation in the inactive area was mainly influenced by the reservoir level change. Finally, the seepage-mechanics numerical analysis of the Xigouwan landslide reveals the deformation mechanism of the active area under long-duration early rainfall. As the rainfall intensity increased from 1 mm/d to 20 mm/d, the pore water pressure at the bottom of the landslide body gradually increased. The internal reservoir level rose and extended to the active area, which caused the landslide body in the active area to go from a stable state to an under-stable state, leading to large deformation in the active area. In addition, the numerical simulation results further showed that the decline of the reservoir level had little effect on the internal seepage field and the stability in the active area. The reservoir level change greatly influenced the internal seepage field in the inactive area, indicating that the weak deformation in the inactive area was mainly affected by the reservoir level change. The complete analysis results of factors inducing the Xigouwan landslide in this paper can help provide early warning. The average rainfall of 20 mm in the past seven days can be used as one of the early warning thresholds for severe deformation in the active area of the Xigouwan landslide.

The eastern Himalayan syntaxis is one of the regions having the most intense tectonic activities, the most complex geological conditions, and the most frequent geohazards in the world. The planning and construction of engineering projects are faced with four types of catastrophic geo-safety risks, including tectonic faulting in the plate tectonic belt, disaster occurrence of the deep-buried tunnels, instability of loose mountains, and regional geological disaster chain. It is a critical topic in the field of engineering geology how to select relatively stable and safe sites in active tectonic zones to minimize the geo-safety risks of planning, construction, and operation of engineering projects. This paper summarized the major geo-safety problems in the eastern Himalayan syntaxis. Accordingly, it revealed that traditional site selection theories hardly satisfy the requirements of the engineering projects in the eastern Himalayan syntaxis area. The site selection encounters geo-safety challenges caused by unclear geological evolution process and construction, prominent disaster risk of tectonic activity and strong earthquake, weak research on the deep tectonic stress field and disaster evaluation, and severe ultra-high-elevation and ultra-long-runout geological disaster chain. Thus, this paper suggested the main research directions of the site selection from five aspects: (1) regional geological evolution and engineering geological problems, (2) active fault and engineering safety risk, (3) complex in-situ stress field and engineering disaster risk, (4) engineering risk of regional geological disaster chain, and (5) theory and method of site selection in eastern Himalayan syntaxis. This paper provides ideas for improving the risk assessment and prevention methods of site selection of engineering projects.

In oil and gas seismic exploration, when the seismic wave propagates in the earth medium, it will encounter obvious absorption and attenuation, resulting in the main frequency of the seismic signal shifting to the low-frequency end. The frequency band narrows and the phase is distorted, which restricts the resolution of seismic exploration to identify thin layers. To obtain a seismic image with higher resolution, this paper introduces a method with effective Q estimation in the imaging domain of seismic reflection data and uses the estimated Q-value to compensate for the attenuation effect through migration to achieve high-resolution imaging. This method introduces the concept of effective Q-value into the time domain. In the time window of the initial viscoelastic time migration image, the effective Q parameters in the time domain are determined through the compensation effect of the data in the time window. Then, the time-depth conversion function is obtained by calculating the imaging ray in the layer velocity in the depth domain, and then the time-depth conversion is carried out for the Q parameters converted to the layer Q-value in the time domain. At last, the key parameter is used as the input of viscoelastic prestack depth migration for viscoelastic compensation imaging of complex structures. Finally, this paper uses the real seismic data from eastern China to verify the effectiveness of the method. The final results show that the process and method developed in this paper can better realize the Q-value modeling and imaging domain compensation in the depth domain, and realize the high-resolution imaging of complex structures.

Petroleum and gas are important strategic resources, among which natural gas as a clean energy resource has always been and still will be the most important energy resource in the foreseeable future, even after cutting global carbon emissions and China peaking carbon emissions. Diversification of energy import channels has been one of the effective measures to alleviate the energy shortage in China. The Arctic region is rich in oil and gas resources and is dominated by natural gas. The vast majority of oil and gas resources found in the Arctic are in Russia, but now more than 80 percent of the Russian natural gas production is already in their oil and gas fields in north Arctic Circle. In 2012, China and Russia officially launched a joint project to develop liquefied natural gas, marking significant progress in China's participation in the development and utilzation of Arctic oil and gas resources, and in fact started the cooperative process to integrate the China-led "Construction of the Silk Road Economic Belt"and the later Russia-led "Construction of Eurasian Economic Union".The total amount of oil and gas resources discovered in the Arctic region is 328.94 billion barrels of oil equivalent, of which oil equivalent amounts to 60.54 billion barrels (8.41 billion tons), only accounting for 2.5% of the world's discovered oil resources; Natural gas amounts to 41.4 trillion cubic meters (268.3 billion barrels, 37.26 billion tons of oil equivalent), and accounts for 15.5 percent of the world's discovered natural gas resources. The vast majority of oil and gas resources discovered in the Arctic region are in Russia, which has a total of 290.5 billion barrels of oil equivalent (40.35 billion tons), accounting for 88.3%, of which natural gas amounts to about 39.47 trillion cubic meters, about 255.79 billion barrels (35.53 billion tons) of oil equivalent, constituting more than 95% of the total discovered natural gas resources in the Arctic. The Arctic also has considerable undiscovered oil and gas resources, accounting for about 15% of the world's total undiscovered amount; The undiscovered natural gas, which mainly distributes in Russia, accounts for 30% of the world's total undiscovered amount. In the context of global warming and crackdown by the US-led Western world, Russia is bound to increase extraction and development of Arctic oil and gas, especially natural gas, and transport them through the Arctic Shipping Lanes to China and other consumer countries, in order to secure its natural gas export revenue and fiscal revenue. This paper takes as the basis the summary of the distribution characteristics of oil and gas resources in the Arctic, oil and gas resources and the Arctic strategy of Russia, and the traffic capacity of the Northern Sea Route (NSR), and reviews the launch and development of the liquefied natural gas joint project as well as the international power politics environment. Moreover, this paper briefly introduces the process of China's successful intervention in the Arctic oil and gas resources project, and puts forward the strategic measures for China to utilize Arctic oil and gas resources.

The rich oil and gas resources in the Arctic have attracted worldwide attention in recent years. According to the academically accepted assessment by the United States Geological Survey, the Arctic oil and gas resources are unevenly distributed, mainly concentrated in Russia, Alaska (the USA), Norway, Canada and Greenland. The exploration and development of oil and gas resources show different characteristics in different countries and regions, which may change under new circumstances. China is a big consumer and importer of oil and gas resources, and the Russian Arctic Region is becoming one of the China's important oil and gas suppliers. This paper presents the current development and utilization status of Arctic oil and gas resources in major Arctic Nations and the future development prospects. Based on China's current participation in oil and gas development and utilization in the Arctic, this paper concludes by suggesting that China should take Russia as a long-term partner in the Arctic oil and gas resources development and the two sides should carry out cooperation in various fields, including project investment, technology investment and channel construction.

Active tectonics is not only the manifestation of the latest crustal activity but also the leading cause of strong earthquakes. With its complex active tectonic system, China has become an area with particularly severe seismic activity and related hazards worldwide. Therefore, a deep understanding of active tectonic characteristics and the occurrence patterns of strong earthquakes in China can help scientifically prevent or mitigate the risk of seismic disasters in urban planning and major engineering construction projects. In order to timely exchange the latest achievements in the field of active tectonics and strong earthquakes, this special issue on Active Tectonics and Strong Earthquakes selected 12 representative papers, mainly covering six different fields, including the earthquake-controlling process of active tectonics, paleoearthquakes, surveying and detection of active faults, seismic geological hazards, application of remote sensing technology and reservoir-induced earthquakes. Based on the new achievements of this issue and the research trends in related fields at home and abroad, it is suggested that future research on active tectonics and strong earthquakes should focus on four aspects: (1) comprehensive understanding of regional seismic hazards from the perspective of active tectonic evolution and active fault systems; (2) quantitative and refined field investigations of active tectonics; (3) application of high-precision remote sensing and various dating techniques continuously expanding the scope and timing of paleoearthquake research; (4) human-induced earthquakes.

Objective Sb deposits are characterized by simple mineral assemblage. The ore-forming ages, sources of ore-forming materials, and genesis of Sb deposits are controversial owing to the absence of suitable minerals for analysis. Sb resources in the South China Sb metallogenic region account for over 83% of the national total, with the Dian–Qian–Gui Sb belt in the southwest being an significant component of this region. Methods Taking the Longlin–Xilin Sb–Au mining district of western Guixi in the central part of the Dian–Qian–Gui Sb belt as an example, this paper systematically summarizes the ore-bearing strata, lithology of ore-bearing wall rocks, ore-bearing structures, and the coexistence relationship of Au and Sb deposits in 86 ore deposits (points) in the area. Combined with the geological characteristics of three typical deposits (Maxiong, Longtan, and Mahao) and the spatiotemporal distribution of Jurassic felsic intrusions, the inherent connection between Sb mineralization and clastic rocks and felsic intrusions was explored. Results (1) Statistics and field works show that the most favorable ore-bearing stratum in the Longlin–Xilin mining district is the Lower Devonian Yujian Formation (D1y) , followed by the Lower Triassic Luolou Formation (T1Ll) and the Middle Triassic Banna Formation (T2b). The lithologies most conducive to mineralization are carbonaceous shale, pyrite-rich sandstone, and siltstone. The Sb content in these strata or lithologies is tens or even hundreds of times higher than the crustal abundance, which has the potential for Sb mineralization. (2) Within the NWW–SEE trending Nongsang–Shijiazhai fault zone in the Longlin area, the middle and late Jurassic felsic intrusions, which have consistent spatiotemporal occurrences with Sb and Au deposits, can directly contribute to antimony mineralization (as sources of Sb and S) and indirectly influence it (as a heat source), both favoring the formation of antimony deposits. (3) Statistical results show that Sb, Au, and Sb–Au deposits account for 48%, 46%, and 6% in the Longlin–Xilin district, respectively. This suggests that the ore-forming fluids for Sb and Au in the study area may originate from different sources. We also can not rule out the possibility that Sb and Au deposits derive from the same fluid. In the latter case, the precipitation of stibnite consumes H2S in the ore-forming fluid, destabilizing the Au complex in the solution and resulting in localized Au precipitation. This competition between Sb and Au in the fluid for H2S leads to a negative correlation in the grades of Sb and Au in coexisting deposits. (4) The study area experienced NS-striking compression in the Indosinian period, followed by the NW–SE shortening in the middle–late Jurassic. The intersection of NWW–SEE and NE–SW faults is the favorable ore-bearing space. The NWW–SEE faults displayed strike-slip movement in response to the NW–SE shortening, whereas the NE–SW faults exhibited transpression. Consequently, the NE–SW faults are less conducive to Sb mineralization compared to the NWW–SEE faults. The distribution direction of the NWW–SEE Douhuang–Xilin fault aligns with the axial direction of the main folds in the area, with most fault planes trending northward, displaying horizontal scratches, silicification, and extensional characteristics. The intersection of the Dohuang–Xilin fault and the NE–SW fracture exhibits significant Sb anomalies. Conclusion Based on the above studies, the promising areas we propose for Sb prospecting in Longlin–Xilin mining district are (1) Black shale and pyrite-rich siltstones of the Yujiang Formation in the core of the Xinzhou anticline as the key strata; (2) The periphery of the concealed intrusions within the NWW–SEE Nongsang–Shijaizhai fault (Longlin County) and the intersection area of the NWW–SEE Douhuang–Xilin fault and the NE–SW fault as the favorable areas. [ Significance ] The findings provide new insights into the genesis and metallogenic regularities of Sb–Au deposits in the study area, enriching the theoretical understanding of Au mineralization processes.

Objective The Haopinggou Ag-Au polymetallic deposit is a typical intermediate-sulfidation epithermal deposit in the Xiong'ershan ore concentration area. Ag-Pb-Zn mineralization mainly occurs in steeply dipping veins and breccia matrix. The relationship between large-scale Pb-Zn mineralization and widely developed alteration minerals remains unclear. Methods In order to discuss chlorite's significance related to Pb-Zn mineralization, chlorite composition in the Haopinggou Ag-Au polymetallic deposit has been analyzed by field geological observation and electron microprobe analysis (EMPA) in this paper. Results Three types of chlorite were observed in the deposit, occurring in altered wall rocks (Type I), in(with) Pb-Zn sulfides (Type II), and in(with) the breccia matrix (Type III). All three types of chlorite are prochlorites and fall within the compositional range of Fe-rich chlorite, indicating that they could be formed in a partially reducing acidic environment. Fe2+ for Mg2+ is the primary substitution in chlorite lattice, suggesting a close association between chlorite formation and mafic wall rocks. Based on the corrected chlorite geothermometer, these chlorites formed under aluminum-saturated conditions in the medium to low-temperature range of 196-239℃. The temperatures of chlorites associated with mineralization (Types II and III) are higher than those in chlorites around quartz veins (Type I). It is believed that during the mineralization process, the hydrothermal fluids evolved from acidic to nearly neutral conditions as the temperature gradually decreased. The initial acidic environment facilitated interaction between water and rocks, promoting the dissolution of surrounding rocks and providing space for the further precipitation of metal sulfides. The evolution of ore fluid properties also corresponds to the deposition process of Ag-Pb-Zn. The genesis of chlorite in the deposit is well-correlated with the ore-forming and holds significant prospecting value. (1) Type I chlorites mainly develop on both sides of quartz veins, formed by the dissolution and metasomatism of basic wall rocks by ore-bearing hydrothermal fluids. Type I chlorite's Fe and Mg components are mostly derived from the wall rocks. Although this type does not contain mineralization, it can be used to trace veins. (2) Type III chlorites reflect the migration process of ore-bearing hydrothermal fluids carrying dissolved minerals (biotite/clinopyroxene), which precipitate with changes in the physicochemical environment. Type III chlorite's Fe and Mg components are mainly introduced by ore-bearing hydrothermal fluids. This type of chlorite fills the intergranular pore spaces between minerals and easily replaces minerals such as biotite and hornblende, exhibiting apparent mineral alteration features in hand specimens, which is beneficial for prospecting.(3) The formation mechanism of Type II chlorites includes the possibilities mentioned above. This type of chlorite is formed by complete dissolution and metasomatism of cement in ore-bearing hydrothermal fluids, forming fine-grained cryptocrystalline chlorite fillings in breccia rocks. Ore-bearing hydrothermal fluids and wall rocks both contribute Fe and Mg in the chlorites. Hand specimens of Type II chlorite are dark green, disseminated and filled in the matrix, making it easy to distinguish. The chemical characteristics of Type II chlorites are similar to those of chemical characteristics of granite-related deposits, implying the contribution of magmatic fluids to ore-forming fluids. Conclusion The Haopinggou Ag-Au polymetallic deposit contains three types of chlorites. Their chemical characteristics all reflect an acidic and reducing metallogenic environment. In cation exchange, the primary substitution is Fe for Mg, and other substitutions are insignificant. The effect of Fe/(Fe+Mg) must be eliminated in order to calculate the temperature of such deposits using chlorite geothermometers. The formation mechanism of the three chlorites is closely related to mafic wall rock, and their chemical properties suggest the involvement of magmatic fluids in ore-forming fluids. Significance These three types of chlorite are well-matched with intense Ag-Pb-Zn mineralization and can serve as key indicators for locating Pb-Zn veins.

Objective Rock fracturing and its subsequent activations are the most basic tectonic deformation modes. However, the classical fracturing criteria (Coulomb-Mohr criterion, Griffith criterion, and Byerlee sliding-friction law) have different limitations in practical applications. Methods Based on the classical fracturing criteria and the analysis of the physical nature of fracturing generation (extensional fracturing and shear fracturing), combined with the generalized shear activation criterion and long-term research practice, a "generalized fracturing activation criterion" is proposed through theoretical analysis in this paper. Conclusion This criterion can be used to quantitatively determine the possibility and types of fracturing of any medium, under any triaxial stress state, and at any orientation interface (including pre-existing weak surface and non-weakness surface). It unifies the Coulomb-Mohr criterion, Byerlee's law, and Griffith's criterion, and extends fracturing to fracturing activation. Significance The proposed criterion has broad application prospects in the fracturing activation-related resource (such as shale gas and hot, dry rock) exploration and development and prediction and prevention of natural disasters (such as earthquakes and landslides).

The concentration, complexity, and significant anisotropy of in-situ stress make it a pressing and challenging issue in engineering geology safety in strong tectonic activity areas. This paper firstly analyzes the application and existing problems of in-situ stress measurement in deep-buried underground engineering in strong tectonic activity areas. Then, it focuses on the application method, technology, and roles of real-time in-situ stress monitoring in deep underground engineering within tectonically active regions. Finally, it discusses the problems that need to be considered in the application of in-situ stress measurement and real-time monitoring. The results show that in the strong tectonic activity area, relying solely on limited deep hole in-situ stress measurements to determine overall stress design parameters for deep underground engineering is inadequate. A comprehensive study of the three-dimensional in-situ stress field is necessary to reveal its spatial distribution characteristics. Different in-situ stress design parameters should be used for different positions of the deep-buried underground project to avoid engineering waste or engineering damages caused by large or small in-situ stress design parameters. In the strong tectonic activity area, the disk core density is inversely proportional to the measured magnitude of the in-situ stress, and the depth range that has yet to form in the cake-shaped core often has the highest in-situ stress and the most concentrated stress, and the deep underground engineering should avoid this depth range. While a major earthquake or major engineering geological problem occurs, real-time monitoring of in-situ stress can dynamically reveal the relative change trend and evolution process of the in-situ stress magnitude of a specific structural site. It can calculate the absolute value of the in-situ stress state in different time domains during the real-time monitoring period without carrying out new absolute in-situ stress measurements. Regional crust stability and deep-buried engineering geological safety risks can be quickly evaluated, and quantitative in-situ stress design parameters and the stress-strain reserved threshold for preventing deformation and breaking can be provided for the damage repair of deep-buried engineering and the risk of fault activity can also be assessed. The research results will offer geological security for the planning, construction, and safe operation and maintenance of major projects in strong tectonic activity areas.

The Jinchuan mining district has undergone a complex tectonic evolution history, and detailed analysis of the post-mineralization deformation characteristics and stress field evolution stages needs to be completed. This paper employs structural analysis methods to stage and correlate the faults in the bedrock of the Jinchuan mining district, determining the structural deformation sequence. It identifies four significant fault combinations in the region, including NE-trending thrust faults and NW-trending strike-slip faults, NE-trending strike-slip faults and NW-trending thrust faults, NW-trending normal faults, and NEE-trending strike-slip faults. The paleo-tectonic stress field of fault is reconstructed by using the lower hemisphere stereographic projection method on the base of studying faults and striations. Combining the paleo-tectonic stress field results with the regional tectonic evolution history, the study accurately defines the stress field evolution stages in the Jinchuan mining district after the mineralization period, which is crucial for understanding regional tectonic evolution and the development of new prospective areas. The results indicate that the Jinchuan mining district experienced four phases of paleo-tectonic stress field after the mineralization period, characterized by multi-stage compression or extension in different directions. These phases responds to a series of regional tectonic thermal events since the Mesozoic respectively: Phase I exhibits a NW–SE compression stress field during the early to middle Jurassic (J1-2); Phase II shows a NE–SW compression stress field during the late Jurassic (J3); Phase III reflects a NE–SW extensional stress field during the Early Cretaceous (K1); Phase IV represents a NE–SW compression stress field since the Late Cretaceous (K2).

This paper examines the enrichment conditions of deep natural gas reservoirs in the Qaidam Basin and delineates the exploration potential utilizing seismic, geological, geochemical, well-logging, and drilling data. The findings indicate the presence of two high-quality gas source formations, namely the Jurassic and Paleogene formations, along the northern margin and the western part of the basin, respectively. The formations both exhibit advanced evolution and robust gas-generating capacity. The deep layers along the northern margin consist of bedrocks and Paleogene clastic reservoirs, while the western deep layers feature Paleogene lacustrine carbonate reservoirs. The reservoirs west of Qaidam Basin are widely distributed on the plane and vertically form multiple reservoir cap combinations. The primary pores, dissolution pores, fractures, and other pore types developed in the reservoirs are considered as the storage space for deep gas accumulation. The continuous active deep faults serve as high-quality channels for deep gas sources; furthermore, the formation of deep structures is well-matched with natural gas generation. The deep hydrocarbon source rocks in the western Qaidam Basin are characterized by early and continuous hydrocarbon generation. Early-generated liquid hydrocarbons undergo high-temperature cracking into gas during later burial, resulting in a robust gas-generating capacity and significant potential for deep resources. The widely developed salt rocks, argillaceous rock, and abnormally high-pressure layers in the deep Qaidam Basin contribute to preserving deep natural gas. In conclusion, it is believed that deep gas reservoirs in the Qaidam Basin are enriched in the traps around hydrocarbon-generating sags with developed faults. Key favorable areas for deep-seated natural gas exploration include the basement rocks of the ancient piedmont uplift in the northern margin of Qaidam, the Paleogene clastic rocks in the central structural belt, and the carbonate rocks along the Yingxiongling structural belt in the western part of the basin.

The Shunyi fault in the Beijing Plain region is a significant late Pleistocene active fault. The Beijing Capital International Airport (BCIA) is situated within the central segment of the Shunyi Fault. Since 2010, ground fissures on the airport's runway have progressively worsened, with a maximum vertical displacement difference of up to 20 cm, severely affecting airport safety. Presently, the impact of Shunyi fault activity on the ground fissures at the BCIA is primarily described qualitatively. This paper, based on research regarding the geometric structure of the Shunyi Fault, Quaternary activity, and investigations of the ground fissures at the Capital Airport, employs the fault dislocation model to quantitatively analyze the influence of the Shunyi Fault's creep-sliding activity as well as the 1996 Shunyi ML 4.5 earthquake on the formation of airport ground fissures. The study also discusses the increasing risk of ground fissure hazards in the event of a potential strong earthquake along the Shunyi fault in the future. The preliminary results suggest that with a vertical activity rate of 0.6 mm/year, 46 years of Shunyi Fault's creep-sliding activity results in differential subsidence of no more than 2.5 cm on both sides of the airport ground fissures, contributing to approximately 20% of the formation and development of these fissures. The impact of the Shunyi ML 4.5 earthquake on the formation of airport ground fissures is minimal. However, if a future M 7.0 earthquake occurs on the Shunyi fault, the estimated maximum land differential subsidence between two sides of the fault could reach 104 cm, increasing the risk of airport ground fissure disasters by a factor of five. Ground differential settlement due to groundwater extraction from the upper and deeper layers of the Shunyi fault's hanging wall contributes about 70% to the formation and development of airport ground fissures, remaining the primary factor. The study's results provide essential scientific references for precise prevention and control of ground fissure disasters at BCIA. Furthermore, to further reveal the causes and mechanisms of delayed geological disasters along the Shunyi fault, such as ground fissures and land differential subsidence, it is recommended to implement dynamic monitoring of cross-fault crustal displacement or deformation at crucial segments.

Objective Geomechanical analysis plays a crucial role in exploring and developing oil and gas reservoirs. However, the study of in-situ stress in the Yijianfang–Yingshan formations of the Middle to Lower Ordovician in the Shunbei oilfield has lagged behind. This paper compares and analyzes the rock mechanics and in-situ stress characteristics of different types of carbonate reservoirs in the Yijianfang-Yingshan formations of the Lower Paleozoic Ordovician in the Shunbei No. 4 block, and explores the control effect of micro-grain structures on the in-situ stress and rock mechanics parameters of carbonate reservoirs. It aims to provide fundamental geological data for the evaluating of ultra-deep carbonate reservoirs in the Shunbei area. Methods This study, based on the spring combination model, determined the rock mechanics and in-situ stress characteristics through rock mechanics experiments and array acoustic logging, and characterized the micro-pore structure of the limestone using casting thin sections and X-ray μ-computed tomography analysis. Results The results indicate that the Young's modulus of the Yijianfang–Yingshan formations ranges from 50 to 89 GPa, the compressive strength from 99 to 136 MPa, and the Poisson's ratio from 0.25 to 0.32. The maximum horizontal principal stress of the formations ranges from 200 to 225 MPa, while the minimum horizontal principal stress ranges from 125 to 160 MPa. Conclusion Significant differences in rock mechanics parameters and in-situ stress exist among different types of carbonate reservoirs in the Yijianfang–Yingshan formations. From Type I to Type III and non-reservoir carbonate rocks, the Young's modulus, compressive strength, and maximum horizontal principal stress increase dramatically, while the Poisson's ratio and minimum horizontal principal stress show little change. Compared to micritic limestone, sandy–bioclastic limestone has larger calcite particles and reduced particle cohesion, resulting in decreased compressive strength and Young's modulus. Some calcite particles appear sub-rounded or rounded with higher three-dimensional particle sphericity, also leading to weaker intergranular engagement and further reduction in compressive strength and Young's modulus. The presence of numerous pores and fractures in sandy-bioclastic limestone facilitates frictional sliding and potential failure along microfractures or particle interfaces, contributing to lower compressive strength and Young's modulus as well. In addition, micritic limestones in the Yijianfang–Yingshan formations are affected by hydrothermal activity, with some dolomite being replaced by quartz, which increases the compressive strength and Young's modulus. The macroscopic mechanical characteristics and rock mechanics parameters of the rock are constrained by the micro-grain structures. The low-value zones of the Young's modulus, compressive strength, and maximum horizontal principal stress in the Yijianfang–Yingshan formations are identified as the advantageous reservoir development zones in the Shunbei No. 4 block.

The Cenozoic tectonic deformation and sedimentary processes in the arcuate tectonic belt along the northeastern margin of the Tibetan Plateau have been influenced by the remote effect of the subduction of the Pacific Plate as well as controlled by the northeastward extension of the Tibetan Plateau. Determining the sedimentary age of the Cenozoic strata is an essential prerequisite for understanding these tectonic deformation and sedimentary processes. However, the sequence and depositional age of the Cenozoic strata in the arcuate tectonic belt is still controversial. This paper systematically studied the Paleoproterozoic to Neoproterozoic sedimentary sequences and stratigraphic ages in the arcuate tectonic belt. The results show that the sedimentary ages of the Sikouzi Formation, the Qingshuiying Formation, the Zhang'enbao Formation, and the Ganhegou Formation in the arcuate tectonic belt are the Middle to Late Oligocene, the Late Oligocene–Early Miocene, the Middle Miocene–Late Miocene, and the Late Miocene-Pliocene, respectively. We systematically analyzed the two unconformities of the Paleocene to Neoproterozoic and refined their formation age as well as geotectonic significance. The first unconformity developed between the Qingshuiying Formation and the Zhang'enbao Formation in the Early-Middle Miocene, which indicates the appearance of the remote effect caused by the northeastward extrusion of the Tibet Plateau at about Early Miocene. The second unconformity developed between the Zhang'enbao Formation and the Ganhegou Formation, which implies the summit of tectonic activities caused by the northeastward extrusion of the Tibet Plateau at about the Late Miocene. It is concluded that the Cenozoic basins have evolved through three stages based on the coupling relationship between the sedimentary process and the tectonic evolution. From the Middle Oligocene to the Early Miocene, the tectonic stress field of the arcuate tectonic belt was controlled by extension under the remote effect of the rollback of the subducted Pacific Plate. The tectonic stress field changed into compression under the effect of the northeastward extrusion of the Tibet Plateau from the Middle to Late Miocene; Significant and sustainable tectonic uplift developed in the arcuate tectonic belt from the Late Miocene to Pliocene, and the Cenozoic basins were divided by the strike-slip fault systems.

The Fen–Wei graben system is an essential Cenozoic extensional fault–depression belt in the central part of the North China craton. Previous research achievements mainly focused on its formation process and dynamic mechanism, but the initial time has been unresolved due to the lack of quantitative dating objects. This paper first reports the granite porphyry dikes in the andesite of the Majiahe formation in the Xionger group of the Zhongtiaoshan orogenic belt adjacent to the Fen–Wei graben system. The dating results of the granite porphyry dikes indicate that the age sequence concentrates mainly in two stages, 1769.8 ± 8.7 Ma and 69.14 ± 0.85 Ma. The former is consistent with the primary age of the volcanic rocks of the Xionger group, representing the characteristics of inherited zircons, and the latter represents the formation age of the granite porphyry dikes. The Ga/Al value ratios of granite porphyry dikes of the Qifeng samples are all greater than 2.6, characterized by enriched silicon, alkali, potassium, depleted calcium, and high magnesium. The rare earth elements are enriched in light and depleted in heavy rare earth elements. The Qifeng granite porphyrite dikes are I-type granites, indicating that the tectonic setting is extensional. The research provides new evidence for the initial time of the southern part of Fenwei graben in the Cenozoic.

This paper briefly describes the theoretical basis of the DRY-1B capacitive component drilling strain gauge (drilling strain gauge). It discusses critical technologies such as micro-displacement sensing, noise reduction, temperature control, performance testing, and calibration. The strain gauge achieved high resolution (≥5×10−11ε), wideband (10–100 Hz optional), extensive dynamic range (≥1×10−3ε), 24-bit AD recording, low power consumption (< 3W), and other technical indicators. Its performance is better than the United States PBO and Japan borehole strain gauge of the same period, and it is an international leading long-term observation instrument for crustal movement, which can basically meet the observation requirements of creep movement with slow accumulation of long-term strain and seismic and volcanic activity with a rapid change of short-term strain. Since 2008, through the application of more than 20 geostress stations, the borehole strain gauge has recorded a large amount of strain information, such as crustal deformation, fault activity, co-seismic strain wave, strain step, and ore pressure activity. Based on the results of the self-consistency test of strain monitoring data of the geostress station in the Beichangshan Mountain and the analysis of seismic mapping capacity of the Turkey earthquake, it is found that the strain curves of the 1#+3# and 2#+4# capacitance sensors at the Beichangshan Mountain stress station are generally stable, and the correlation coefficient R2 is 0.95. The annual variation rate of the differential strain of 1#–3# and 2#–4# elements is 10−8 magnitude, which reflects that the shear stress is dominant in the Long Island area and the stress environment of seismic activity is relatively high. The strain gauge was used to observe the apparent co-seismic strain response of Turkey’s M 7.8 and M 7.5 earthquakes on February 6, 2023. In particular, it obtained the M 7.8 main seismic surface wave period of 50–60 s, presenting an out-facing wave anomaly. Theoretically, the strain wave generated by the M 0.74 earthquakes within 100 km can be distinguished, and the application demonstration effect has been achieved. The borehole strain gauge has good popularization value and application prospects in geodynamics research and internal dynamic geological disaster monitoring.

As an essential parameter in earthquake prediction and risk assessment research, the b-value has received extensive attention and discussion. In this study, we chose a nonlinear mixed model to fit the earthquake magnitude-frequency distribution to the China Earthquake Catalog database. The b-values calculated by this method were used to analyze and evaluate the seismic activity. This paper takes 27 seismic belts in China as the research area, collects earthquake data of magnitude 4.7 and above from 1920 to 2019 as a complete earthquake catalog, performs mixed model fitting and G-R model fitting for these 27 seismic belts, and compares the fitting effects. Taking Tibet as the test area, the earthquake catalog data from 1920 to 2019 were selected, and the nonlinear mixed model was applied to fitting the earthquake magnitude-frequency model in Tibet at 10-year intervals. Firstly, the earthquake data screened in the study area was classified and counted by magnitude and time; Secondly, the relevant variables in the nonlinear mixed model were calculated using the moment magnitude and seismic moment conversion formula. Finally, a nonlinear hybrid model was used to perform nonlinear regression analysis on the seismic data. The results show that: When low values of b occur, earthquakes occur around the corresponding periods. When b-values are low, earthquakes of large magnitude and low frequency occur. When b-values are relatively high, earthquakes of small magnitude and high frequency occur. Applying the nonlinear mixed model to the complete seismic data in China and neighboring regions enables a more comprehensive analysis of the data and overcomes the limitations of the traditional modeling method in analyzing earthquakes of high magnitude. The b-value will be calculated by rational analysis, which enhances the analysis and evaluation of seismic catalog data.

Recently, water injection-induced earthquakes caused by faulting instability have become a prominent geological safety issue for safely exploiting deep geothermal resources. This study investigates whether the future large-scale development of deep geothermal resources in the Gaoyang uplift will destabilize buried faults. There has a great amount of karst thermal reservoir in the Gaoyang low uplift, Hebei province. To find out whether the large-scale deep geothermal exploitation in the future will induce faults distributed in and around Gaoyang geothermal reservoir to become unstable, firstly, we calculate the initial stable state of the main buried faults based on Mohr-Coulomb criteria using the comprehensive in-situ stress field of North China; then, under Hsieh and Bredehoeft hydrological model, we calculate the possible excess pore pressure caused by water injection for 10~40 years at representative geothermal wells; subsequently, combing this perturbation with the initial stable state, we obtain the fault slip potential of the main buried faults from 2022 to 2062 based on a probabilistic approach; ultimately, we discuss the impact on the changes of fault slip potential due to varying angles between the maximum horizontal principal stress and the fault orientation. The main conclusions of this work can be drawn as follows. With the injection rate of 170 m3/h, the maximum excess pore pressure caused by a single geothermal well does not surpass 11 MPa, and it obeys a power decrease distribution with increasing distance from the center of the injection well; its influence scope is no more than 8 km. Continuous water injection strongly changes the stability of those buried faults distributed 2 km within the geothermal wells, and fault-slip potentials of some segmental faults even exceed 85%, corresponding to high unstable risk. Under 50 years of water injection at an injection well, the fault-slip potential of faults with different strikes within 2 km from the injection well increases rapidly with the declining angle among its orientation and the regional maximum horizontal principal stress. This paper's study methodology and associated findings can offer geoscientific justification for the safe exploration and exploitation of deep geothermal resources domestically and internationally. This study can provide a method reference for the location of injection wells and the selection of faults in different orientations in geothermal fields at home and abroad, thus promoting the safe and efficient development and utilization of geothermal resources.

The Qionghua–Liantang fault belt, located at the boundary between the Fushan depression and the Haikou uplift, is the result of the impact of the uneven extension of the NE-trending Beibu Gulf rift. The Qionghua–Liantang fault belt passes through the Changliu New District and the major projects of the island-looping high-speed railway in Haikou, directly impacting the planning and construction of the Hainan Free Trade Zone. The article uses tectonic geomorphic survey, geophysical exploration, and drilling exploration to reveal that the Qionghua–Liantang fault consists of three NW-trending buried and semi-buried normal faults, which are the Wuyuanhe–Daoxincun fault (F1-1), the Yongzhuangshuiku fault (F1-2), and the Haikouzhuanwachang fault (F1-3). The width of the Qionghua–Liantang fault belt is about 1.8 km, and the length is about 17 km. The vertical displacement of the fault belt is 8.7~41.6 m since the Quaternary. The latest active age of these three faults is the late Pleistocene; the vertical activity rate was less than 0.1 mm/a. It is worth noting that the vertical activity rate of the Haikouzhuanwachang fault (F1-3) is higher than the other two faults and has more vigorous activity. Combining the tectonic background, the latest active age of the Qionghua–Liantang fault, and its relationship with Quaternary volcanic activity, this paper puts forward suggestions on the planning and construction of the Hainan Free Trade Zone and building avoidance of active fault.

Formation strain can directly affect the generation of structural fractures. According to the magnitude of structural strain, the location and intensity of structural fracture development can be predicted, and the chief fracture development areas in the study area can be divided. This paper takes the fourth member of the Yingcheng formation (referred to as the YING-4 section) in the Xuzhong area of the Xujiaweizi rift in the Songliao basin as the research object. Based on establishing a detailed 3D structural model of the study area, we used the “structural restoration” method to restore the paleo-structure of the study area and calculated finite strain values to predict the planar distribution of structural fractures. The research shows that the YING-4 section in the study area mainly includes three fracture-making periods, namely the end of the Yingcheng formation, the Quantou–to–Qingshankou formation, and the Nenjiang formation. Among them, the tectonic deformation at the end of the Yingcheng formation and the Quantou–to–Qingshankou formation is relatively strong, which is the main formation period of the fracture. The study area is divided into three types of fracture development zones according to the relationship between strain size and test gas production. Type I fracture development zone has been verified by well-drilling, indicating that the prediction results of fractures using structural strain are reliable. Type Ⅱ fracture development zone can be used as an important direction for the next step of deep natural gas exploration. Type Ⅲ fracture development zone has low productivity, and the fractures have limited effect on reservoir reconstruction.

The unstable slopes of BH01, BH02, and BH03 in the Yigong landslide source area in Tibet threaten the safety of major engineering facilities downstream. In order to prevent and control the disaster risk caused by the high-elevation sliding of blocks, it is urgent to analyze the geological structure of the slope in the above-mentioned source area and their deformation trends. Based on the Pleiades digital elevation model with a precision of 2 m and its topographical shadow, this paper draws up evidence from three aspects: quantitative geomorphology, geological structure, and landslide science. In addition, it is preliminarily determined that the source area of the Yigong landslide has four secondary slope units, including the cuesta in the front imbricated thrust-fault zone, the block in the thrust-fault zone, the block in the strike-slip fault zone, and the NE-trending rift zone. There are two primary control structural planes in the slope, dipping southeast and southwest, respectively. The geological survey of the line has confirmed that the above two groups of structural planes are related to thrust faults and strike-slip faults in the imbricated nappe. The NE-trending rift crosscutting the ridge may be related to the recent EW-extensional deformation of the nappe. With the above-mentioned geological structures, the slopes in the Yigong landslide source area show multi-stage and multi-phase deep sliding along the NE-trending rift zone and have the creep-tension-shear sliding mechanism with rock landslide. According to the extension depth of the tensile fractures in the source area, the BH02 block has the potential risk of accelerated slippage. Moreover, the BH03 block is also unstable.

The Namjag Barwa syntaxis is in the eastern Himalayan syntaxis area with the most intensive neotectonic activity. There are many late Quaternary active fault belts and strong seismicities. The tectonic stability of these active fault belts, such as the Jiali, Dongjiu-Milin, and Motuo fault belts, may influence the project's construction. In-situ stress is a critical parameter for estimating regional tectonic stability. Currently, there is a lack of abundant in-situ stress results about the Namjag Barwa syntaxis. It is challenging to assess geological safety risks for major projects. Based on focal mechanism solutions, the paper reveals the orientation of the maximum principal stress surrounding the Namjag Barwa syntaxis using the stress tensor inversion method. According to the critical condition of fault instability, the magnitudes of principal stresses around the Namjag Barwa syntaxis are also estimated by combining the inversion of the stress shape ratio and the frictional coefficient. The results indicate that the maximum principal stress direction in the Namjag Barwa syntaxis area is NE-NNE. The maximum and minimum horizontal principal stresses increase linearly with depth at a gradient of 0.032~0.0355 MPa/m and 0.0227~0.0236 MPa/m, respectively. Heterogeneous features of the in-situ stress field still exist. Generally, the results estimated in this study are in good concordance with the in-situ stress measurements. They can provide reliable in-situ stress parameters for evaluating the tectonic stability in the Namcha Barwa region.

The connectivity rate plays an essential role in the stability evaluation of engineering rock masses such as slopes and dam foundations. This paper takes the foundation rock mass of an arch dam of a hydropower station in southwest China as the research object. Based on the field-measured data and the self-developed fissure network simulation program, we used the Monte-Carlo stochastic simulation method to calculate the connectivity rate of the gently dipping structural planes and the strength parameters in different shear directions of rock mass on the left and right bank of the hydropower station. The results show that the connectivity rate of the left and right banks of the hydropower station is different in different shear directions, and the overall fissure connectivity rate is low. The fissure connectivity rate of the gently dipping structural planes at PD02 on the right bank is about 27.35%, the friction coefficient is 1.04, and the cohesion is 0.89 MPa. The research results can provide a theoretical reference for this and similar projects.

China is an ancient civilization country with a history of 5000 years and the habitat of ancient human beings. There are abundant descriptions of geological phenomena and geological processes in the vast number of ancient books and folklore. Due to the scientific and technological progress and the breakthrough of production mode brought about by the transformation of social productive forces and production relations, the development of the geological cause is characterized by stages. Including the exploration of geological phenomena by human beings in ancient times, this paper divides the development history of China's geological cause into six stages: geological relics in the Stone Age; geological cognition in the Ancient Age; geological investigation in the Enlightenment Age; geological survey and research in the Foundation Age; geological work in the period of rapid development, and geological cause in the new era of reform and opening up. Each stage is further discussed in terms of the important geological events, the content and characteristics of geological work, the main research achievements and the contributions to the national economic and social development.

The Ke'eryin area in Sichuan province is one of the large rare metal ore concentration areas in the Songpan–Garze metallogenic belt. Numerous granite pegmatite dikes spread around the Ke'eryin mass. However, locating rare metal dikes in such a large pegmatite field has always been one of the challenges in this region. This paper summarized the geochemical element distribution in the Ke'eryin pegmatite and put forward geochemical indexes, e.g., characteristic element indexes, indicator indexes and grade indexes, to locate rare metal ore in the Ke'eryin area based on a systematic petrogeochemical analysis of two-mica granite, pegmatite microcline albite granite, different pegmatite types and typical deposits. Characteristic element indexes include Li, B, Sn, Rb, Be, Nb and Ta, etc. Indicator indexes for lateral variation are Cs, Tl, F, Zr, Y and ΣREE elements as well as values, e.g., TiO2/Ta, Zr/Hf, Ta/Zr, Nb/Ta, K/Na, etc., while indicator indexes for vertical variation include B, U, Zr, Be, Sn, Rb, Sr, Ba, Tl and In, etc. The variation in these indexes can be used to locate rare-metal-mineralized pegmatite, indicating ore bodies in a deep basin. Grade indexes are aluminum saturation index（A/CNK, A/NK）and rittmann index(σ), etc. Li ore grade is positively correlated with aluminum saturation but is negatively correlated with alkalinity. Grade index variation is a good indicator of lithium enrichment in ore bodies.

At present, the study of accretionary orogenic belts and collisional orogenic belts has achieved numerous insights and improvements. However, continental subduction, which often occurs during the oceanic and continental transition, has not received enough attention for a long time, such as what kind of structural deformation characteristics it has and how it affects the evolution of the orogenic belt. This paper studied two Cenozoic orogenic belts (the Taiwan orogenic belt and the Yarlung Zangbo River orogenic belt) and one Mesozoic orogenic belt (the Qiangtang orogenic belt) in order to clarify the unique structural deformation characteristics of continental subduction and its interaction with orogenic processes. It is found that the subduction of continental crust often forms a double-layer structure in the orogenic belt. The upper part is a set of thrust imbricate composed of Smith strata, and the lower part is a set of subduction complexes with a “blocks in the matrix” structure. The upper and lower parts of the double-layer structure are similar, mainly slope facies–submarine fan facies rocks and little shelf facies rocks. Due to the similar deformation time, the double-layer structure should be a structural system formed in different depths by the subduction of the same passive continental margin. We suppose that the subduction of the slope–submarine fan is the main factor for the formation of the double-layer structure. The subsequent continental shelf subduction could induce the collision and thus lead to strain’s gradual propagation to the craton’s interior, resulting in the foreland fold-thrust. Also, the double-layer structure is often destroyed during the collision, so the deeply underplated continental subduction complex can be exhumed to the shallow level. Therefore, this study also emphasizes the importance of continental subduction and the exhumation of subducted crustal rocks in the evolution of orogenic belts.

Based on a brief introduction of the spatial distribution, rock types and formation ages of the late Mesoarchean–early Neoarchean (2.6~3.0 Ga) rocks in some key areas of the North China Craton, this paper summarizes the ages and geochemical and Nd-Hf-O isotopic compositions of the granitoids all over the craton. The late Mesoarchean–early Neoarchean basement shows the following features: (1) The late Mesoarchean–early Neoarchean magmatism is almost continuous, with a peak period of 2.70~2.75 Ga; (2) The late Mesoarchean–early Neoarchean rocks widely occur in the North China Craton, mainly in the Eastern Ancient Terrane, the Central Ancient Terrane and the Southern Ancient Terrane; (3) The intrusive rocks are mainly tonalite in composition, with trondhjemite, granodiorite, K-rich granite and gabbro-diorite; (4) The supracrustal rocks are commonly small in scale and scatter in granitoids. The rock types are mainly meta-basaltic rocks. In some areas, there are meta-komatiites, meta-andesitic-dacitic rocks and meta-clastic sedimentary rocks; (5) 2.6 Ga can be regarded as the boundary between the early and late Neoarchean in the North China Craton; (6) TTG rocks show large Sr/Y and La/Yb variations, plotting in the high-, medium- and low-pressure TTG areas in the Sr/Y–Y and La/Yb–Yb diagrams. Except for a few K-rich granites, the late Mesoarchean–early Neoarchean rocks are commonly depleted in Nd-Hf isotope compositions, with the magmatic zircon being similar in O isotope composition to that of the Archean magmatic zircon worldwide; (7) Many regions have similar geological characteristics, but some regions show great uniqueness. The research futher supports the understanding that, similar to many other typical cratons worldwide, the late Mesoarchean–early Neoarchean is the most important period of continental accretion in the North China Craton, and the main difference is that the North China Craton underwent a strong and widespread magmato-tectonothermal event at the end of the Neoarchean.

In recent years, a large number of large-area sand bodies have been drilled in the Neogene in the southern Bohai Sea, and several 100-million-ton oilfields have been discovered, indicating that the lower member of the Minghuazhen Formation has enormous exploration potential. The source-sink elements of the development of such sand bodies are unclear, which seriously restricts the exploration of lithologic reservoirs in the lower member of the Minghuazhen Formation. Using paleontology, heavy minerals, seismic, drilling and other data, this paper explores the source-sink system and its control on large-area lithologic reservoirs in the lower member of the Minghuazhen Formation of the southern Bohai Sea. The results show that: The Yanshan-Liaoxi uplift, the Liaodong uplift, the Luxi uplift and the Jiaodong uplift mainly develop source-sink systems in four directions in the study area’s lower member of the Minghuazhen Formation. Next, the Luxi uplift and the Jiaodong uplift are relatively close. The Luxi uplift and the Liaodong uplift significantly impact the source-sink system in the study area’s lower part of the Minghuazhen Formation. In contrast, the Yanshan-Liaoxi uplift has a weaker impact on the source-sink system. Three sedimentary systems, including rivers, river-lake interactions and lakes, are mainly developed in the study area’s lower member of the Minghuazhen Formation. Among them, the sand bodies formed by river-lake interactions and lake shallow water deltas are larger. The study area’s lower member of the Minghuazhen Formation has favorable source-sink conditions for creating large-scale sand bodies. Among them, temperate-subtropical climate, sufficient rainfall, developed paleo-water system, felsic metamorphic rocks and magmatic parent rocks, and frequent expansion and shrinkage of lakes are beneficial to the development of large-area sand bodies. The connection of channel sand–sheet sand–channel sand leads to the development of large-scale lithologic traps in the study area’s lower member of the Minghuazhen Formation. Compared with channel sand alone, river-lake interactions and shallow water deltas have the potential to form large-area lithologic reservoirs. This understanding can help explore large Neogene oil and gas reservoirs in the Bohai Sea.

In this paper, zircon SHRIMP U-Pb geochronology, petrology, mineral chemistry, petrogeochemistry, Sm-Nd and Lu-Hf isotopes were studied for the eastern part of the Dupangling pluton, which is located at the western section of Nanling at the junction of Hunan and Guangxi provinces. The zircon SHRIMP U-Pb dating results show that the age of coarse-to-medium-grained porphyritic biotite monzogranite is 215.6±2.1 Ma, medium-grained porphyritic biotite monzogranite 220.5±1.8 Ma, medium-grained rapakivi biotite monzogranite 222.8±1.5 Ma. Combined with the age of fine-grained muscovite monzogranite as 209.7±3.1 Ma obtained in the previous research, it is suggested that the emplacement time ranges from 222.8 Ma to 209.7 Ma, and the pluton is derived from the Indosinian magmatic activity rather than the Yanshanian as previously thought. The mineral-chemical characteristics of rapakivi K-feldspar and biotite phenocryst indicate that the magma temperature, pressure and composition have gone through fluctuation during the formation process, and biotite phenocryst was formed by multiple melting under the underplating by basaltic magma in this area. The Dupangling biotite monzogranites have higher contents of SiO2 and K2O+Na2O, A/CNK value ranges between 1.02 and 1.39 and Rittman index (δ) between 0.93 and 2.18, belonging to the peraluminous calc-alkaline. Moreover, these monzogranites are enriched in REE, Rb, Th and U with higher content of HFSE (Nb, Y and Ga), depleted in Ba, Sr and Eu with higher ratios of TFeO/MgO and Ga/Al, showing the characterisitics of A-type granite. The isotope εNd(t) value ranges from -8.74 to -8.13, and the T2DM value from 1.71 to 1.66 Ga; the zircon isotope εHf(t) value ranges from -14.1 to -1.4, and the T2DM value from 2.14 to 1.34 Ga. It reveals that the Dupangling biotite monzogranites mainly originated from the partial melting of ancient crustal materials and were mixed with a certain degree of depleted mantle materials. The metamorphic peak period of the Indosinian movement is from 258 Ma to 243 Ma. South China was in an extensional tectonic setting after 233 Ma and mantle-derived basalt magma was in a wide range of underplating, which caused the crustal material remelting to form the Dupangling Indosinian aluminous A-type granite (rapakiwi granite) under an extensional background.

The Zongling landslide group in Guizhou Province is characterized by strong regularity of disaster formation, concentrated development and severe threat. It is represented in the coal mining-induced geological hazards in western Guizhou and eastern Yunnan. In this paper, InSAR and optical remote sensing were used for nuanced identification to obtain the regional landslide information, and the landslide deformation-failure mode in the Zongling region was summarized. Based on this, the volume-distance statistical formula suitable for landslide risk assessment in this region was established, and the typical disaster bodies ware calculated. Some important insights are gained: Underground coal mining is the major contributor to the deformation of the edge of Table Mountain in Zongling. InSAR observation results show that the deformation in the Zongling area has prominent zonal characteristics, and the annual average deformation velocity is between -20.4~10.2 cm/a, which corresponds well with the lower goaf. The areas with great displacement are concentrated in the edge zone of cuesta, with coal mining subsidence and slope gravity superimposed; There are 64 deformations in the Zongling area, including 37 landslides, 27 cracks, and 2 dangerous deformed bodies. Landslides mainly occur in the dark grey limestone strata and dark purplish-red argillaceous siltstone strata of the Feixianguan Formation. According to the lithology and deformation characteristics of the slip source, the landslides can be classified into two types: pull-toppling and pull-clipping, and the former is distinguished by large particle size, long movement distance, and severe threat. The formula for calculating the slip distance of rock landslide debris flow has good applicability to the slip distance of coal mining-induced landslide developed in the "upper hard and lower soft" strata in the Zongling area, and the verification error is less than 5%. The formula is used to calculate the dangerous deformed bodies of Zuojiaying and Jingjiao in the study area, and the danger avoidance distance is predicted to be 220~386 m. The proposed method of coal mining-induced landslide risk assessment based on differential interferometry and optical image play an exemplary role for the prevention and control of coal mining-induced landslides in western Guizhou and eastern Yunnan.

Based on the first-hand data obtained from the field survey in terms of geology, landforms, earthquake ruins, this paper focuses on the activity behavior of the Sagaing fault, as well as the damaged buildings and seismic surface rupture zone generated by the 2012 earthquake. The Sagaing fault striking nearly NS is an active large-scale dextral strike-slip fault, with a horizontal slip rate of 18~20 mm/a. Many strong earthquakes more than M 7 have occurred along the Sagaing fault zone historically, and so far, there are still ruins of the earthquakes, such as the 1839 Innwa, Mandalay, M 8 earthquake, the 1930 Bago M 7.3 earthquake and the 1930 Phyu M 7.3 earthquake. The 2012 Thabeikkjin M 7.0 earthquake caused serious damage to pagodas, civil and other buildings, forming an at least 45 km-long seismic surface rupture with bank collapses, landslides, seismic faults and so on. The epicenter intensity of the earthquake is estimated to be IX. Under the dextral strike slip of the fault, the ground fissures show a trend of regular left-step en echelon, and the included angle with the strike of the Sagaing fault is generally 20°~30°; The large-scale ground fissures mostly show a "S" type. The regular left-step en echelon trend of ground fissures and the faulted ground features indicate that the seismic surface fracture are obviously characterized by dextral strike slip. The horizontal dextral displacements caused by the 2012 earthquake are generally between 40~90 cm, and the maximum reaches 102 cm. The surface rupture characteristics and the results of focal mechanism solutions show that the event is caused by the dextral strike-slip of the Sagaing fault.

Alkylphenols are a kind of compounds produced by alkylation of phenolic compounds. Compared with other non-hydrocarbon compounds, alkylphenols are more soluble in water. In this paper, through three groups of oil-water distribution experiments at different temperatures (25 ℃, 45 ℃ and 65 ℃), different brine concentrations (4000 mg/L, 6000 mg/L and 8000 mg/L) and different crude oil types (X37, X45 and X61), the distribution characteristics of alkylphenols between oil and water were studied, and the variation law of alkylphenol distribution coefficient was determined. The results show that the oil-water partition coefficient increases with the increase of alkyl molecular weight of homologues; The oil-water partition coefficient of alkylphenols decreases with the increase of temperature, and alkyl homologues with higher molecular weights are more sensitive to temperature; The partition coefficient of alkylphenol in oil-water system increases with the increase of water salinity. According to the experimental results, temperature and salinity of water phase will cause the difference of oil-water partition coefficient of alkylphenol, and the influence of temperature is greater than that of salinity. The distribution behavior of alkylphenols between oil and water can provide more reference for the secondary migration of crude oil and the direction of water drive front in reservoir development.

The Longquan pluton is a rare Caledonian granitic rock mass in southern Zhejiang. Studies on the Longquan pluton using petrology, geochemistry, and chronology were conducted in this paper, which reveal that it is composed of granite-monzogranite assemblage (granitoid) and tonalite-trondhjemite-granodiorite assemblage (TTG). The two types of rocks are generally enriched in large ion lithophile elements Rb, Ba, Th, U and K, and depleted in high field strength elements Nb, Ta, P and Ti, showing the characteristics of island arc magmatic rocks. The geochemical characteristics of the TTG rocks show that they belong to the typical high-pressure type TTG, and its magma originated from the remelting of the basic lower crust under the action of subducted slab fluid. While the granitoids were mainly derived from partial melting of ancient crustal sediments. Neither of them was significantly contaminated by mantle. The zircon SHRIMP U-Pb and LA-ICP-MS U-Pb dating results show that the Longquan pluton was formed between 443±3 Ma~410±3 Ma. Combined with its petrological and geochemical characteristics, it is indicated that the subduction of oceanic crust had still existed in the Longquan area until early Devonian.

The thrust directions in foreland thrust belts have not been explained on theory. Based on Coulomb fracture criterion and deformation asymmetry in foreland thrust belt, the origins of fore-thrust and back-thrust faults are analyzed in this paper. Two potential conjugate fractures would occur in initial deformation stage, and the fracture requiring less applied forces might develop into thrust fault under the quasi-static equilibrium caused by deformation asymmetry in foreland thrust belts. The applied forces needed to create fault movements include the frictions along both the detachment surface and the fault surface. The fore-thrust faults will occur in most deformations in foreland thrust belts. However, where either the principal stress axes tilt toward foreland or the intersections point of the two conjugate fractures are on the detachment surface, the back-thrust faults will be preferable to occur. The applied force, the frictions along the detachment surface and the geometries of the slipping terranes will determine the principal stress axes. The findings will help to explain the selectivity of the fault dips in both contractional and extensional deformation areas.

The Sanhe Pb-Zn deposit is studied in this paper through detailed field and underground geological investigations, structural geological surveys, drilling profile analysis combined with petrological and mineralogical analysis of ores and altered wall-rocks. We then discussed the ore-controlling structures and their distribution patterns, the styles of mineralization and alteration, the coupling relation between the mineralization and fault structures. Our results show that the mineralization in the Sanhe deposit show structure-controlled characteristics, and with dominant ore bodies trending NWW, dipping SSW. The extent of the ore-controlling faults can reach hundreds of meters to a few kilometers long, with relative stable occurrence. In the field, the ore-controlling faults occur as altered foliated zones but with tensional breccia veins and druse texture in them, showing a reactivated shear fault signature. NWW- and NNE- trending faults show post-ore deformation characteristics and usually with lamprophyre, syenite porphyry or calcite ±quartz ±fluorite ±clay mineral veins occuring in them. The NNW- and NNE- trending faults and related veins crosscut the mineralized carbonate-quartz veins and NWW-trending faults indicating a post-ore brittle deformation and hydrothermal activity. The post-ore faults and related hydrothermal veins usually occur as branching, bifurcation or irregular shapes and with druse texture in the center of the veins implying a extensional faults. Although the post-ore faults can slightly dislocate the ore bodies and contemporaneous hydrothermal veins, the displacement is negligible for exploration. The alteration around the non-mineralized calcite veins is dominated by clay alteration together with minor disseminated pyrite. Combined the structure-controlled mineralization and the alteration related Pb-Zn minerlization, it is concluded that the NWW-tending faults with silicification, pyritization, chloritization alteration halo, can be used as significant prospecting criteria in the deposit and the neighbouring area.

The southwestern Tianshan Mountains is an important producing area of the Meso-Cenozoic stratabound glutenite-type Cu-Pb-Zn deposits in Xinjiang. Sareke copper mine, Wulagen lead-zinc mine, Huayuan copper mine and Jiashi copper mine are the representative deposits, which all occur in the red bed basin on the edge of the uplift denudation area and are strictly controlled by strata. The lower part of the ore-bearing basin is composed of coal-bearing hydrocarbon-generating rocks, the middle part is well-permeable glutenites as the Cu-Pb-Zn reservoir, and the overlying layer is a sealed cap formed by gypsum rocks and mudstones, showing the ore-forming characteristics of co-enrichment of Cu-Pb-Zn-Uranium-coal-natural gas in the same basin. In this paper, we summarized the sedimentary-tectonic evolution of these ore-bearing basins and the characteristics of ore-bearing layers, and analyzed the ore-controlling conditions and metallogenic characteristics of typical copper, lead and zinc deposits. Combining with comparative analysis, we summarized the regional metallogenic regularity of the Meso-Cenozoic glutenite-type Cu-Pb-Zn deposit, and hold the view that organic matter is closely related to Cu-Pb-Zn mineralization. Moreover, it is inferred that Cu-Pb-Zn-lean ore bodies were formed over the original source layer in the uplift caused by the superimposition of oilfield brine; Cu-Pb-Zn-rich ore bodies were formed by the superimposition of deep-source ore-forming fluids from the Himalayan fault structure. The metallogenic model of the middle Cenozoic stratabound glutenite-type Cu-Pb-Zn deposits in the southwestern Tianshan Mountains provides a basis for the exploration of the known mines in their deep and edge, and also provides guidance for the regional prospecting work.

This paper aims to ascertain the depositional paleoenvironment since the late Quaternary in the central Hebei plain. We measured the 20.74 m-deep Xibozhang section and analyzed the collected samples for grain size and optically stimulated luminescence (OSL) tests. OSL dating results indicate that the deposits were formed during 102~8.67 ka, belonging to the late Pleistocene to early Holocene. Analysis of lithology and grain size show that, the section is fluvial deposit with typical binary structure, which can be further divided into channel deposit and floodplain deposit. The channel deposits are mainly medium-coarse sand containing mica fragments, with oblique bedding. Frequency curves is characterized by positive bias bimodal with moderate to poor sorting, and the probability cumulative curves are mainly two-stage dominated by jump components. The floodplain deposit is mainly clayey silt with well-preserved shell fossils and calcareous nodules. Most frequency curves are negative bias bimodal with poor sorting, and the probability cumulative curves are mainly two-stage dominated by suspension components. The C-M diagram shows that the Xibozhang section consists largely of uniformly suspended deposits, belonging to typical meandering river deposits. Comparing the measured section with the loess section of Jingyuan, we found that the Xibozhang section could be divided into three stages from the bottom up. The lower part, 16.14~20.74 m, is the deposits of the late stage of the last interglacial period, with warm and humid climate, dominated by silty deposits; The middle part, 3.18~16.14 m, is the deposits of the last glacial period, with dry and cold climate. The grain size shows the fine-coarse-fine characteristic, individually corresponding to the early interglacial stage, interglacial stage and maximum glacial stage of the last glacial period; The upper part, 0.2~3.18 m, is the deposits of the post glacial stage with similar characteristics of 16.14~20.74 m, dominated by clay and clayey silty sand deposits. Grain size analysis reveals that the late Quaternary depositional environment of the Baoding depression in central Hebei Plain is mainly of fluvial environment, and the distribution of grain size stage is the material respond to glacial-interglacial climate.

Nowadays artificial seismic exploration is recognized as one of the most effective means to detect hidden faults in urban areas. However, good seismic exploration data in highly urbanized areas is often unavailable limited by the excitation source and strong interference. In this paper, a seismic detection of excitation mode of high-power spark source was carried out in the Dazhi River area, in view of the developed urban water network in Shanghai. We did comparison tests on elements such as energy excitation of spark source, water depth of discharge and seismic imaging effects of different sources, and obtained the best excitation parameters for seismic exploration in inland river areas (east section of Dazhi River) in Shanghai. The validity of seismic exploration by spark source in urban water network is confirmed. Compared with other conventional excitation methods, EDM seismic exploration data has higher signal-to-noise ratio and can reach a deeper exploration depth, which helps to get good results from the detection of hidden faults in urban areas.

Digital elevation model (DEM) is used to realize the digital simulation of terrain surface (i.e. the digital representation of terrain surface shape) through the limited terrain elevation data. As a new tool to describe the terrain, it provides a new field of vision for people to study the evolution process of the earth's surface. The application status of DEM in many fields are summerized in this paper, including basic topographic factors, watershed geomorphological features, reconstruction of paleogeomorphology, tectonic geomorphological development model, tectonic activity classification, geomorphological classification and environmental assessment, geomorphological parameter algorithms and computing platform development. Our research generally focuses on land, with river geomorphology and mountain geomorphology as the main objects. The research process changes from the early qualitative description of geomorphology to the semi-quantitative and quantitative analysis of a variety of geomorphological parameters. The research scale extends from a small watershed to the whole orogenic belt in space and from a few hours to millions of years in time. However, many factors can influence the accuracy of quantitative analysis results of tectonic geomorphology, such as the uncertainty of the time series of tectonic geomorphology evolution, the complexity of the acquisition of geomorphological parameters, the diversification of terrain model algorithms and the error factors in the process of DEM generation. Therefore, while summarizing the previous research results, some thoughts are given on the application of DEM in tectonic geomorphology.

Shanghai is located in the alluvial plain of the Yangtze River Delta, the merge area of the Huangpu River and Suzhou River. The unique geographical and sedimentary environment have formed the shallow sand layers in Shanghai. Due to the significant urbanization process in Shanghai, geological hazard analysis, particularly the assessment for seismic liquefaction hazard in the Shanghai urban area has become an subject to be studied urgently. In this paper, we presented a regional liquefaction hazard analysis model. Based on the borehole Standard Penetration Test (SPT) data and regional Peak Ground Acceleration (PGA) zonation of the Shanghai area, we analyzed liquefaction risks with different probability of exceedance in 50 years. As our results indicated, under the condition that earthquake with 10% probability of exceedance in 50 years happens, more than 66.0% of the land area in Shanghai will not be affected by earthquake-induced liquefaction, 21.8% will only surfer modest liquefaction, and only 12.3% has the risks of serious liquefaction. These places cover Chongming island, Hengsha island, Changxing island and the banks of the Huangpujiang River and the Suzhou River. Provided that earthquake with 2% probability of exceedance in 50 years happens, due to the overall increase of peak ground motion acceleration, not less than 46.25% of the land area may suffer from modest to serious liquefaction risks. Although the rare seismic liquefaction risks exist, the probability of that is quite low. The current high fortification intensity for Shanghai in Chinese Code for Seismic Design of Building may result in unnecessary cost of construction. Our study provides new ideas and suggestions for perfecting the Code for Seismic Design of Building for Shanghai.

In this paper, we investigated the Terror Rift where the last stage of Cenozoic rifting in the West Antarctic Rift System (WARS) took place. The International published and domestic sampled during CHARE seismic reflection profiles are utilized. Combining with drilling data, all the stratigraphic reflections are identified and unified in the entire study area for the subsequent interpretation. The rift fault patterns in the study area can be divided into syn-sedimentary faults, intra-layer faults and negative flower structure. According to faulting, we delineated the east and north boundary of the Terror Rift. Moreover, Cenozoic faulting activities are divided into three stages with strongly inheritance between each one of them. The timing of faulting activities gradually becomes younger from the Adare Basin in the north to the Terror Rift in the south, which is attributable to the transmission of rifting from north to south. In order to further reveal the geophysical characteristics of the study area, we investigated effective elastic thickness (EET) based on the fan wavelet transform technique. The anomalously low EET anomalies observed in the front of the Transantarctic Mountains(TAMs) is related to the rifting and magmatism in the late Cenozoic, probably indicating the extensional area of the western Ross Sea.

West Antarctica is mainly composed of five distinct micro-continental blocks, namely Haag Nunataks, Antarctic Peninsula, Thurston Island, Marie Byrd Land and Ellsworth-Whitmore Mountains. In order to understand the geological evolution of West Antarctica, this paper presents a brief overview of the main magmatic events of the five blocks and their tectonic significance. The oldest rock is the Precambrian orthogneiss from Haag Nunataks with zircon U-Pb age of~1238 Ma, indicating the development of Mesoproterozoic arc magmatism in West Antarctica. The other four blocks preserve the geological records since~500 Ma. During the Paleozoic, the Ellsworth-Whitmore Mountains block was formed in a rapidly subsiding continental rift basin environment which was related to the back-arc extension caused by the Ross Orogeny, and the magmatic activity was rare. A set of convergence-related magmatism occurred in the middle to late Paleozoic in Mary Byrd Land block, which was formed in an active continental margin environment. The Antarctic Peninsula-Thurston Island blocks record the development of the Carboniferous-Permian arc during this time. During the Mesozoic, the tectonic setting of these blocks began to differentiate since the Jurassic. The Ellsworth-Whitmore Mountains block records Jurassic intra-plate magmatism, which may be associated with large igneous province. In Marie Byrd Land, the lithology changed from Ⅰ-type arc magmatic rocks to A-type alkaline magmatic rocks in the Jurassic-Early Cretaceous to the mid-Cretaceous period. This reflects a major change in tectonic setting from subduction to rifting during the mid-Cretaceous. The Jurassic-Cretaceous flare-up in arc magmatism record on the Antarctic Peninsula-Thurston Island blocks with a pulse of Jurassic large igneous provinces. These are the product of the interaction of continuous subduction and rifting. The Cenozoic magmatism was represented by the Antarctic Peninsula block with arc magmatism continuing until the Eocene. The temporal and spatial distribution of the arc magmatism was related to the subduction and collision of spreading ridge which was cut into several segments by sinistral transform faults.

A set of high-K and low-Al tholeiites intercalated with volcanic clastic rocks developed in King George Island (Western Antarctica), belonging to the island arc volcanic rock series. Moreover, the longest record of glacial deposition in Antarctica is preserved on the island, which provides the important evidence of the Antarctic Ice Sheet evolution. Fossils of plant leaves, sporopollen, stems, invertebrate animals and bird footprints which were abundantly found in the outcropped Cenozoic continental strata of King George Island, started to decrease from the Eocene to the early Miocene, showing an obvious downward trend of plant diversity, and the surviving sparse vegetation was only the tundra species around the glacier. The studies of ice marine strata and paleontology suggest that the late Oligocene marine strata mainly correspond to high-energy environment and the early Miocene marine strata correspond to low energy environment. This paper explores the Cenozoic paleontological characteristics and paleoenvironment of King George Island, and the investigations allow us to understand the trend of paleontological diversity and provide evidence for the reconstruction of the Antarctic paleoenvironment as well.

The Transantarctic Mountains across the central Antarctic continent are the Ross orogenic belt formed by westward subduction of the Paleo-Pacific underneath the East Gondwana active continent margin in the early Paleozoic. The sedimentary, deformation and metamorphism, and granitic magmatic intrusion in this stage represent the process of the Ross Orogeny. Due to the significant difference in age among the three elements mentioned above, there is no precise time defined on the Ross Orogeny. In this paper, detrital zircon U-Pb dating of gravel and sand samples from moraines and coastal sediments in the Inexpressible Island of Northern Victoria Land was carried out. The ages of four samples with different gravel diameters range from 2443 to 323 Ma and are mainly concentrated between 530~450 Ma, with a peak age of~485 Ma. Most of the zircons show oscillatory zoning in CL images and have Th/U ratios great than 0.1 (mainly>0.4), with REE characteristics indicating a magmatic origin. Therefore, these ages reflect the timing of magmatic activity in the provenance of the loose sediment samples. The age composition of detrital zircons is consistent with the age of magmatic intrusion, intracontinental deformation and depositional stratigraphy in the surrounding areas, suggesting that the magmatic activity in the Northern Victoria Land and its surrounding areas might have lasted up to 450 Ma in the intracontinental deformation stage, which may represent the end time of the Ross Orogeny. These results provide a new constraint for the tectonic evolution of the Ross Orogeny on the Gondwana continental margin.

There is still no consensus among researchers about whether intergranular pores in oil-bearing sandstone are primary pores or secondary pores. Distinguishing between cementation and dissolution of dotted calcite can effectively identify intergranular pore types. In this paper, taking the diagenetic environment evolution and diagenesis sequence as the thread, we carefully observed the casting slices from the Xinhe Formation sandstones in the Yabrai Basin and finely dissected the microphenomenon by focusing on the calcite cements in its relation between the origins of substance and dissolution fluids and the occurrence mode. The genesis of the dotted calcite was clarified thus, and then the intergranular pore types and reservoir space types in the sandstones were identified. The study results show that the dotted calcite in the intergranular pore is the dissolution residue of the disseminated calcite formed in the early diagenetic stage, and the dissolution type is the consistent dissolution. The dissolution fluid, organic acid fluid formed during the middle diagenetic stage, caused the secondary pores. Therefore, it is concluded that the reservoir space in the Xinhe Formation sandstones in the Yabrai Basin consists of the secondary intergranular pores and the secondary intragranular pores such as dissolution pores of cements of feldspar, lithoclast, lithoclast.

At present, the mechanism of earthquake is still based on elastic rebound theory—Earthquake is caused by the release of elastic energy of rock strata due to fault dislocation. But more and more scholars began to question whether the elastic energy after fault faulting can really reach the huge energy released by the actual earthquake. Therefore, it is necessary to study the nature of destructive strong earthquake and its real energy source after the initial movement. According to the characteristics of the reservoir and its pressure in the sedimentary strata, it is concluded that there are a lot of high-pressure fluid in the reservoir, and its pressure can be released under certain conditions, resulting in fluid physical explosion, which may be an important part of strong earthquake energy. The calculation results show that when the fault ruptures and penetrates the reservoir with large area, the elastic energy produced by the pressure release can reach the energy released by the earthquake with magnitude above 8.0; Artificial engineering activities can also lead to the release of small-scale fluid pressure, such as blowout during drilling, earthquake induced by hydraulic fracturing, etc. At the same time, according to the analysis of the waveforms and propagation ray paths of the seismic stations close to the epicenter, it is considered that the strong earthquake wave may not be S-wave, but P-wave. Therefore, it cannot be ruled out that the strong earthquake might be caused by explosion. A large number of direct or indirect evidence, such as the time domain and frequency domain characteristics of seismic waves recorded by several stations during the Wenchuan earthquake, the explosion phenomena observed on the ground, and the cores obtained by scientific drilling after the earthquake, indicate the possibility of the release of this kind of fluid explosion energy. Finally, this paper proposes that the seismicity can be divided into three stages: The stage Ⅰ of micro rupture, in which there is fluid activity and electrokinetic effect, but the initial earthquake motion is not triggered; The stage Ⅱ of fault rupture after the initial earthquake motion; The strong earthquake stage Ⅲ, which is caused by the release of fluid pressure.

Strategic rare metals have irreplaceable important use to emerging industry development. Granitic pegmatite is the main source of rare metals, and their fluid characteristics and metallogenic mechanism are hot topics. This paper mainly focuses on fluid properties and metallogenic mechanism of granitic pegmatite-type rare metal deposits. Ore-forming fluids of the granitic pegmatite-type rare metal deposits are generally enriched in volatile (B, P, F and H2O) and ore-forming elements, with low viscosity, low nucleation rate, but strong element solubility and mobility. The ore-forming fluids of the granitic pegmatite-type rare metal deposit were argued to be captured under the condition of high temperature and high pressure, or the temperature of as low as 350℃ under the condition of supercooling. The high crystallization differentiation evolution of granitic magma and the small proportion of crustal material rich in ore-forming elements are the two main mechanisms for the formation of ore-forming granitic pegmatite. Fluid immiscibility and constitutional zone refining are important means for further enrichment of rare metals in the process of magmatic hydrothermal evolution. The largest Jiajika granitic pegmatite-type lithium deposit in China is an ideal laboratory to study this kind of deposit.