Pub Date : 2024-04-30DOI: 10.2113/2024/lithosphere_2024_137
Chuanqin Yao, Huaqiao Zhong, Zhehao Zhu
This article highlights the development of a large shaking table test for sand liquefaction analysis. Two soil containers of different sizes were fabricated. The first one was small (0.87 m × 0.87 m × 1.20 m) in which the reconstitution and saturation methods could be easily tested. The dry tamping (DT) method was used to fabricate a model specimen. The subsequent field measurements suggested that the DT method provided a good distribution of sand grains in different cross sections. Before supplying the model specimen with water, carbon dioxide was flushed to replace air bubbles. This helped in obtaining a good degree of saturation, later verified by a digital moisture meter. For a given inlet water flux, the recorded pore water pressure displayed a quasi-linear trend, suggesting a good internal void system. This reconfirms the effectiveness of the DT method to yield homogeneous model specimens. The second soil container was huge (4 m × 4 m × 2 m) and used to explore liquefaction behavior in real engineering dimensions. Flexible foams were mounted on the side walls to mitigate the boundary effect. Although the boundary effect still manifested itself near the edges of the container during base shaking, half of the model specimen underwent a correct simple shear condition. For further analysis, vane shear tests were carried out before and after the liquefaction test. It was found that the intermediate layer, in general, suffered from the most severe liquefaction failure.Research activities into sand liquefaction have been conducted since the 1964 Niigata earthquake in Japan [1, 2]. In the laboratory, monotonic and cyclic triaxial tests are widely adopted to investigate liquefaction responses. As for laboratory element tests, the state parameter (considering both relative density and consolidation stress [3, 4]) and degree of saturation are two decisive indicators [5, 6] for examining the liquefaction potential. Besides, the soil fabric [7, 8] formed in different specimen reconstitution methods [9-11] has recently been proven to be another influential factor in controlling liquefaction triggering.Although triaxial tests certainly provide valuable insights into the mechanism of sand liquefaction, the understanding based on these tests is still limited by the size effect and thus only represents the liquefaction behavior of a unit soil element. This is far from representing a natural soil extent subjected to seismic loading in a semi-infinite space. Therefore, shaking table tests play an increasingly important role in the context of geotechnical earthquake engineering and contribute to improving the understanding of the liquefaction phenomenon. Many successful configurations have been presented in the literature [12-17]. Teparaksa and Koseki [18] performed a series of liquefaction tests on a shaking table to assess the effect of liquefaction history on liquefaction resistance of level ground. Ko and Chen [19] investigated the evolution of mechanical p
{"title":"Development of a Large Shaking Table Test for Sand Liquefaction Analysis","authors":"Chuanqin Yao, Huaqiao Zhong, Zhehao Zhu","doi":"10.2113/2024/lithosphere_2024_137","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2024_137","url":null,"abstract":"This article highlights the development of a large shaking table test for sand liquefaction analysis. Two soil containers of different sizes were fabricated. The first one was small (0.87 m × 0.87 m × 1.20 m) in which the reconstitution and saturation methods could be easily tested. The dry tamping (DT) method was used to fabricate a model specimen. The subsequent field measurements suggested that the DT method provided a good distribution of sand grains in different cross sections. Before supplying the model specimen with water, carbon dioxide was flushed to replace air bubbles. This helped in obtaining a good degree of saturation, later verified by a digital moisture meter. For a given inlet water flux, the recorded pore water pressure displayed a quasi-linear trend, suggesting a good internal void system. This reconfirms the effectiveness of the DT method to yield homogeneous model specimens. The second soil container was huge (4 m × 4 m × 2 m) and used to explore liquefaction behavior in real engineering dimensions. Flexible foams were mounted on the side walls to mitigate the boundary effect. Although the boundary effect still manifested itself near the edges of the container during base shaking, half of the model specimen underwent a correct simple shear condition. For further analysis, vane shear tests were carried out before and after the liquefaction test. It was found that the intermediate layer, in general, suffered from the most severe liquefaction failure.Research activities into sand liquefaction have been conducted since the 1964 Niigata earthquake in Japan [1, 2]. In the laboratory, monotonic and cyclic triaxial tests are widely adopted to investigate liquefaction responses. As for laboratory element tests, the state parameter (considering both relative density and consolidation stress [3, 4]) and degree of saturation are two decisive indicators [5, 6] for examining the liquefaction potential. Besides, the soil fabric [7, 8] formed in different specimen reconstitution methods [9-11] has recently been proven to be another influential factor in controlling liquefaction triggering.Although triaxial tests certainly provide valuable insights into the mechanism of sand liquefaction, the understanding based on these tests is still limited by the size effect and thus only represents the liquefaction behavior of a unit soil element. This is far from representing a natural soil extent subjected to seismic loading in a semi-infinite space. Therefore, shaking table tests play an increasingly important role in the context of geotechnical earthquake engineering and contribute to improving the understanding of the liquefaction phenomenon. Many successful configurations have been presented in the literature [12-17]. Teparaksa and Koseki [18] performed a series of liquefaction tests on a shaking table to assess the effect of liquefaction history on liquefaction resistance of level ground. Ko and Chen [19] investigated the evolution of mechanical p","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"41 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.2113/2024/lithosphere_2023_129
Ziran Jiang, Jian Jiao, Qiaomu Qi, Xingyu Deng
After multistage tectonic movement and evolution, large superimposed oil and gas basins generally developed many igneous rocks in the early rifting stages. The lithology and lithofacies of igneous rocks are complex, which is easy to lead to the distortion of the underlying migration velocity field and thus the response of seismic pseudofaults. Also, because of the obvious shielding and absorption effect of igneous rocks on seismic waves, the waveform quality of underlying strata is poor and the seismic response characteristics of faults are fuzzy. Currently, relevant studies have shown that the influence of igneous rock can be eliminated by the prestack depth migration with an accurate igneous rock velocity model. However, improving the accuracy of the velocity model needs to be corrected by well-logging data, resulting in poor applicability of the existing velocity modeling technology underlying igneous rocks without well, which is an obvious technical bottleneck. In this paper, the secondary strike-slip fault in Shuntuoguole low uplift of Tarim Basin, which has great oil and gas exploration potential but a very low degree of drilling, is selected as the research object. Aiming at difficult fault detection underlying igneous rocks caused by lack of drilling, the accuracy of fault seismic identification is improved by “interpretative fault preprocessing” and “fault sensitive attribute optimization.” In addition, through the “extreme hypothesis method” to maximize the complex migration velocity and simulate the underlying target layer distortion maximization, we realize the quantitative elimination of seismic pseudofaults. The practical application shows that this technology can determine the true and fake underlying faults quantitatively without establishing an accurate igneous rock velocity model. It is crucial not only for exploring oil and gas in the Tarim Basin’s secondary strike-slip faults but also for offering a method and technical guide for identifying faults in other basins affected by igneous rocks.Large superimposed oil and gas basins have undergone multiple periods of tectonic movement and evolution and generally experienced multiple periods of strong magmatic activity in the early stages of rifts or rifts, preserving numerous igneous rocks. As a high-velocity rock mass, igneous rock has two major impacts on the precise structural imaging of its underlying strata [1]. First, igneous rocks strongly shield and absorb seismic waves, leading to the blurring of seismic response characteristics of small structures and faults in the underlying strata. Second, the uneven distribution of thickness, the lateral and vertical variability of lithology, and the significant velocity differences between different lithologies of igneous rock bodies make it difficult to accurately describe the areal distribution, thickness, and velocity of high-velocity igneous rocks before migration imaging. This reduces the accuracy of the migration velocity field a
{"title":"Quantitative Elimination of Seismic Pseudofaults and Fine Analysis of True Faults Underlying Igneous Rocks of No-Well Areas: A Case Study of Shuntuoguole Uplift in Tarim Basin","authors":"Ziran Jiang, Jian Jiao, Qiaomu Qi, Xingyu Deng","doi":"10.2113/2024/lithosphere_2023_129","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_129","url":null,"abstract":"After multistage tectonic movement and evolution, large superimposed oil and gas basins generally developed many igneous rocks in the early rifting stages. The lithology and lithofacies of igneous rocks are complex, which is easy to lead to the distortion of the underlying migration velocity field and thus the response of seismic pseudofaults. Also, because of the obvious shielding and absorption effect of igneous rocks on seismic waves, the waveform quality of underlying strata is poor and the seismic response characteristics of faults are fuzzy. Currently, relevant studies have shown that the influence of igneous rock can be eliminated by the prestack depth migration with an accurate igneous rock velocity model. However, improving the accuracy of the velocity model needs to be corrected by well-logging data, resulting in poor applicability of the existing velocity modeling technology underlying igneous rocks without well, which is an obvious technical bottleneck. In this paper, the secondary strike-slip fault in Shuntuoguole low uplift of Tarim Basin, which has great oil and gas exploration potential but a very low degree of drilling, is selected as the research object. Aiming at difficult fault detection underlying igneous rocks caused by lack of drilling, the accuracy of fault seismic identification is improved by “interpretative fault preprocessing” and “fault sensitive attribute optimization.” In addition, through the “extreme hypothesis method” to maximize the complex migration velocity and simulate the underlying target layer distortion maximization, we realize the quantitative elimination of seismic pseudofaults. The practical application shows that this technology can determine the true and fake underlying faults quantitatively without establishing an accurate igneous rock velocity model. It is crucial not only for exploring oil and gas in the Tarim Basin’s secondary strike-slip faults but also for offering a method and technical guide for identifying faults in other basins affected by igneous rocks.Large superimposed oil and gas basins have undergone multiple periods of tectonic movement and evolution and generally experienced multiple periods of strong magmatic activity in the early stages of rifts or rifts, preserving numerous igneous rocks. As a high-velocity rock mass, igneous rock has two major impacts on the precise structural imaging of its underlying strata [1]. First, igneous rocks strongly shield and absorb seismic waves, leading to the blurring of seismic response characteristics of small structures and faults in the underlying strata. Second, the uneven distribution of thickness, the lateral and vertical variability of lithology, and the significant velocity differences between different lithologies of igneous rock bodies make it difficult to accurately describe the areal distribution, thickness, and velocity of high-velocity igneous rocks before migration imaging. This reduces the accuracy of the migration velocity field a","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"21 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.2113/2024/lithosphere_2023_354
Yinyu Li, Li Qing, Yongshui Kang, Rui Zhang, Xiang Li, Bin Liu, Zhi Geng
With the increase in the mining depth of coal mines in China, the problem of large deformation of roadways owing to high-ground pressure has become prominent even under enhanced support systems. To reduce the high pressure on the surrounding rock, this study investigates a pressure-relief method for deep roadways using drilling borehole groups. Based on a deep roadway in the Huainan mining area of China, the influences of drilling parameters, such as borehole diameter, length, and arrangement were investigated. The results indicate that the fan-shaped arrangement of the borehole group can compensate for the dilatancy deformation of the surrounding rock. The peak stress of the surrounding rock is reduced and transferred to the inner part of the surrounding rock. Furthermore, a field experiment was conducted on an experimental roadway. The deformation of the roadway was monitored and compared with that of an adjacent roadway that did not apply the pressure-relief method. The monitoring results indicated that the deformation of the experimental roadway was significantly reduced.In China, coal is a major energy resource, which plays a dominant role in energy systems. China’s coal reserves are approximately 597 trillion tons, out of which approximately 53% are buried in the deep stratum (exceeding the depth of 1000 m) [1-3]. With the increase in the coal mining depth in recent years, an increasing number of roadways suffer from high geo-stress, which induces large deformation and failure and poses serious threats to mining safety [4-6]. Therefore, preventing large deformations of deep roadways with high geo-stress has become an important issue in coal mining. To prevent large deformation problems in deep roadways, engineers usually enhance the support system. For example, the use of high-strength and super-long bolts [6, 7], a method of bolting and shotcreting, U-steel support, grouting and floor bolting casting [3-5], and the reduction of the interval spacing of the supporting structures [4, 5]. Although some development has been achieved, large roadway deformations still frequently occur under high-ground pressure. The resistance offered by the supporting structure is extremely limited. Repeated repair is difficult and results in significant economic losses. Another approach to prevent large deformations of roadways is to release the high-ground pressure around the roadway using special measures. For example, floor grooving releases the high stress that accumulates on the floor, which is conducive to treating floor heaves [7, 8]. The rock mass within the range of pressure relief is destroyed by using high-pressure water injection softening and blasting pressure-relief methods, which reduces the elastic modulus and strength of the rock mass [5-7]. Drilling boreholes [6-9] in coal seams is beneficial for preventing coal and gas outburst accidents. Consequently, the accumulated energy on the surrounding rock surface decreases, leading to the release of
{"title":"Method for Pressure Relief in Deep Coal Mine Roadways Using Borehole Groups and Its Application to Guqiao Coal Mine","authors":"Yinyu Li, Li Qing, Yongshui Kang, Rui Zhang, Xiang Li, Bin Liu, Zhi Geng","doi":"10.2113/2024/lithosphere_2023_354","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_354","url":null,"abstract":"With the increase in the mining depth of coal mines in China, the problem of large deformation of roadways owing to high-ground pressure has become prominent even under enhanced support systems. To reduce the high pressure on the surrounding rock, this study investigates a pressure-relief method for deep roadways using drilling borehole groups. Based on a deep roadway in the Huainan mining area of China, the influences of drilling parameters, such as borehole diameter, length, and arrangement were investigated. The results indicate that the fan-shaped arrangement of the borehole group can compensate for the dilatancy deformation of the surrounding rock. The peak stress of the surrounding rock is reduced and transferred to the inner part of the surrounding rock. Furthermore, a field experiment was conducted on an experimental roadway. The deformation of the roadway was monitored and compared with that of an adjacent roadway that did not apply the pressure-relief method. The monitoring results indicated that the deformation of the experimental roadway was significantly reduced.In China, coal is a major energy resource, which plays a dominant role in energy systems. China’s coal reserves are approximately 597 trillion tons, out of which approximately 53% are buried in the deep stratum (exceeding the depth of 1000 m) [1-3]. With the increase in the coal mining depth in recent years, an increasing number of roadways suffer from high geo-stress, which induces large deformation and failure and poses serious threats to mining safety [4-6]. Therefore, preventing large deformations of deep roadways with high geo-stress has become an important issue in coal mining. To prevent large deformation problems in deep roadways, engineers usually enhance the support system. For example, the use of high-strength and super-long bolts [6, 7], a method of bolting and shotcreting, U-steel support, grouting and floor bolting casting [3-5], and the reduction of the interval spacing of the supporting structures [4, 5]. Although some development has been achieved, large roadway deformations still frequently occur under high-ground pressure. The resistance offered by the supporting structure is extremely limited. Repeated repair is difficult and results in significant economic losses. Another approach to prevent large deformations of roadways is to release the high-ground pressure around the roadway using special measures. For example, floor grooving releases the high stress that accumulates on the floor, which is conducive to treating floor heaves [7, 8]. The rock mass within the range of pressure relief is destroyed by using high-pressure water injection softening and blasting pressure-relief methods, which reduces the elastic modulus and strength of the rock mass [5-7]. Drilling boreholes [6-9] in coal seams is beneficial for preventing coal and gas outburst accidents. Consequently, the accumulated energy on the surrounding rock surface decreases, leading to the release of","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"51 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.2113/2024/lithosphere_2023_338
Yu Ma, Suping Yao, Ning Zhu, Huimin Liu, Junliang Li, Weiqing Wang
The physical properties of shale oil reservoirs under overburden pressure are of great significance for reservoir prediction and evaluation during exploration and development. Based on core, thin section, and SEM observations, as well as test data such as XRD, TOC, and porosity and permeability under pressure conditions, this study systematically analyzes the variation of physical properties of different lithofacies shales in the Jiyang depression and the influence of rock fabric on the physical variation under pressure. The porosity and permeability of shale samples significantly decrease under pressure. According to the phased reduction in porosity and permeability, the pressurization process is divided into three pressure stages: low pressure (<8 MPa), medium pressure (8–15 MPa), and high pressure (>15 MPa). The reduction of porosity is fastest in the low-pressure stage and slowest in the medium-pressure stage. The reduction of permeability is fastest in the low-pressure stage and the slowest in the high-pressure stage. The rock fabric has a significant impact on porosity and permeability under pressure conditions. The permeability of laminated shale and bedded shale is higher than that of massive shale under pressure, and the permeability loss rate is lower than that of massive shales. Especially under lower pressure, the difference can be 10–20 times. In addition, the reduction rate of porosity and permeability under pressure is negatively correlated with felsic minerals content, which is positively correlated with carbonate minerals content and clay minerals content. The contribution of clay minerals to the porosity reduction rate is dominant, followed by carbonate minerals. The contribution of carbonate minerals to the permeability reduction rate is dominant, followed by clay minerals. The TOC content has no significant impact on the porosity and permeability of shales under pressure in the study due to the low maturity.With the change in global energy structure, shale oil and gas has become the core growth point of China’s oil and gas resources [1-4]. In the past decade, a series of important progresses have been made in the exploration and development of shale oil and gas in China, including breakthroughs in the exploration of shale oil in Junggar Basin, Ordos Basin, Jianghan Basin, Songliao Basin, and Bohai Bay Basin [5-8]. However, due to the heterogeneity of shales and the complexity of geological conditions in China, the prediction and evaluation of shale oil reservoirs still face many challenges [3, 9, 10].Many studies have shown that rock fabric, such as laminated structure and mineral composition, has a significant influence on the pore development and physical properties of shale oil reservoirs [10-14]. However, most of these studies were conducted under unpressurized conditions, and there are some errors with the formation conditions, which affect the prediction and evaluation of shale oil desserts. To recover the real physical
{"title":"Influence of Rock Fabric on Physical Properties of Shale Oil Reservoir Under Effective Pressure Conditions","authors":"Yu Ma, Suping Yao, Ning Zhu, Huimin Liu, Junliang Li, Weiqing Wang","doi":"10.2113/2024/lithosphere_2023_338","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_338","url":null,"abstract":"The physical properties of shale oil reservoirs under overburden pressure are of great significance for reservoir prediction and evaluation during exploration and development. Based on core, thin section, and SEM observations, as well as test data such as XRD, TOC, and porosity and permeability under pressure conditions, this study systematically analyzes the variation of physical properties of different lithofacies shales in the Jiyang depression and the influence of rock fabric on the physical variation under pressure. The porosity and permeability of shale samples significantly decrease under pressure. According to the phased reduction in porosity and permeability, the pressurization process is divided into three pressure stages: low pressure (<8 MPa), medium pressure (8–15 MPa), and high pressure (>15 MPa). The reduction of porosity is fastest in the low-pressure stage and slowest in the medium-pressure stage. The reduction of permeability is fastest in the low-pressure stage and the slowest in the high-pressure stage. The rock fabric has a significant impact on porosity and permeability under pressure conditions. The permeability of laminated shale and bedded shale is higher than that of massive shale under pressure, and the permeability loss rate is lower than that of massive shales. Especially under lower pressure, the difference can be 10–20 times. In addition, the reduction rate of porosity and permeability under pressure is negatively correlated with felsic minerals content, which is positively correlated with carbonate minerals content and clay minerals content. The contribution of clay minerals to the porosity reduction rate is dominant, followed by carbonate minerals. The contribution of carbonate minerals to the permeability reduction rate is dominant, followed by clay minerals. The TOC content has no significant impact on the porosity and permeability of shales under pressure in the study due to the low maturity.With the change in global energy structure, shale oil and gas has become the core growth point of China’s oil and gas resources [1-4]. In the past decade, a series of important progresses have been made in the exploration and development of shale oil and gas in China, including breakthroughs in the exploration of shale oil in Junggar Basin, Ordos Basin, Jianghan Basin, Songliao Basin, and Bohai Bay Basin [5-8]. However, due to the heterogeneity of shales and the complexity of geological conditions in China, the prediction and evaluation of shale oil reservoirs still face many challenges [3, 9, 10].Many studies have shown that rock fabric, such as laminated structure and mineral composition, has a significant influence on the pore development and physical properties of shale oil reservoirs [10-14]. However, most of these studies were conducted under unpressurized conditions, and there are some errors with the formation conditions, which affect the prediction and evaluation of shale oil desserts. To recover the real physical ","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"23 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.2113/2024/lithosphere_2023_361
Kai Zhang, Yipeng Xu, Zhenchun Li, Zilin He, Yiming Pan
Joint Waveform inversion (JWI) uses the results of reflection waveform inversion (RWI) as the initial model for full waveform inversion (FWI). Compared with the FWI, the JWI method can obtain more information about the structure of the subsurface medium. The reason is that the reflected waveform inversion can invert the long wavelength component in the middle and deep areas. In JWI, reflected waveform inversion is used to obtain the reflected wave information in the simulation record by demigration, which is computationally more expensive than FWI; the least squares reverse time migration (LSRTM) also obtains the reflected wave information in the simulated record by demigration. In order to effectively use the reflected wave information brought by the high computational amount of reverse migration in JWI, this paper proposes a simultaneous inversion method of JWI and LSRTM (JWI-LSRTM). This method can simultaneously perform an iterative update of the subsurface medium velocity of JWI and the migration imaging of LSRTM, which improves the calculation data utilization rate of each forward and inversion process. In the model test, the effectiveness of the method is proved.Reflected waveform inversion (RWI) is a technique that obtains reflected wave information from simulated records through reverse migration. It can invert long wavelength components in the middle and deep layers [1-3], but its computational cost is higher than full waveform inversion (FWI). FWI is a high-precision inversion method [4-6] with the potential to provide accurate models of subsurface media parameters. Joint waveform inversion (JWI) [7] leverages the results of reflection waveform inversion (RWI) as an initial model for FWI. Compared to FWI, JWI can retrieve more information about the subsurface media structure [8]. This is because RWI can obtain long wavelength components in the middle and deep layers [9, 10]. Ren (2019) proposed an adaptive JWI method that automatically switches between RWI and FWI by adjusting the weight factor with the number of iterations and allowable errors, without manually pausing the switch [11]. This approach addresses the limitations of traditional waveform inversion methods and improves the efficiency and accuracy of subsurface media modeling.The LSRTM [12, 13] is based on the Born approximation, and the reflection coefficient is solved by many iterations with the known background velocity. LSRTM is also used to obtain the reflected wave information from simulated records.In the above three methods, the simulated data and observed data are inverted using the generalized least squares method to obtain the corresponding gradient. However, the computational cost of forward modeling the wave equation and reverse migration is substantial, accounting for at least 90% of the total computation time in these three methods. As a result, the inversion cycle is often prolonged [14, 15]. Now there are a variety of programming techniques (MPI, Openmp, Open
{"title":"Optimal Inversion Method Based on Joint Waveform Inversion and Least Squares Reverse Time Migration","authors":"Kai Zhang, Yipeng Xu, Zhenchun Li, Zilin He, Yiming Pan","doi":"10.2113/2024/lithosphere_2023_361","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_361","url":null,"abstract":"Joint Waveform inversion (JWI) uses the results of reflection waveform inversion (RWI) as the initial model for full waveform inversion (FWI). Compared with the FWI, the JWI method can obtain more information about the structure of the subsurface medium. The reason is that the reflected waveform inversion can invert the long wavelength component in the middle and deep areas. In JWI, reflected waveform inversion is used to obtain the reflected wave information in the simulation record by demigration, which is computationally more expensive than FWI; the least squares reverse time migration (LSRTM) also obtains the reflected wave information in the simulated record by demigration. In order to effectively use the reflected wave information brought by the high computational amount of reverse migration in JWI, this paper proposes a simultaneous inversion method of JWI and LSRTM (JWI-LSRTM). This method can simultaneously perform an iterative update of the subsurface medium velocity of JWI and the migration imaging of LSRTM, which improves the calculation data utilization rate of each forward and inversion process. In the model test, the effectiveness of the method is proved.Reflected waveform inversion (RWI) is a technique that obtains reflected wave information from simulated records through reverse migration. It can invert long wavelength components in the middle and deep layers [1-3], but its computational cost is higher than full waveform inversion (FWI). FWI is a high-precision inversion method [4-6] with the potential to provide accurate models of subsurface media parameters. Joint waveform inversion (JWI) [7] leverages the results of reflection waveform inversion (RWI) as an initial model for FWI. Compared to FWI, JWI can retrieve more information about the subsurface media structure [8]. This is because RWI can obtain long wavelength components in the middle and deep layers [9, 10]. Ren (2019) proposed an adaptive JWI method that automatically switches between RWI and FWI by adjusting the weight factor with the number of iterations and allowable errors, without manually pausing the switch [11]. This approach addresses the limitations of traditional waveform inversion methods and improves the efficiency and accuracy of subsurface media modeling.The LSRTM [12, 13] is based on the Born approximation, and the reflection coefficient is solved by many iterations with the known background velocity. LSRTM is also used to obtain the reflected wave information from simulated records.In the above three methods, the simulated data and observed data are inverted using the generalized least squares method to obtain the corresponding gradient. However, the computational cost of forward modeling the wave equation and reverse migration is substantial, accounting for at least 90% of the total computation time in these three methods. As a result, the inversion cycle is often prolonged [14, 15]. Now there are a variety of programming techniques (MPI, Openmp, Open","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"1 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141253434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-12DOI: 10.2113/2024/lithosphere_2023_197
Denghui He, Yaguang Qu, Guanglong Sheng, Bin Wang, Xu Yan, Zhen Tao, Meng Lei
The accurate forecasting of oil field production rate is a crucial indicator for each oil field’s successful development, but due to the complicated reservoir conditions and unknown underground environment, the high accuracy of production rate forecasting is a popular challenge. To find a low time consumption and high accuracy method for forecasting production rate, the current paper proposes a hybrid model, Simulated Annealing Long Short-Term Memory network (SA-LSTM), based on the daily oil production rate of tight reservoirs with the in situ data of injection and production rates in fractures. Furthermore, forecasting results are compared with the numerical simulation model output. The LSTM can effectively learn time-sequence problems, while SA can optimize the hyperparameters (learning rate, batch size, and decay rate) in LSTM to achieve higher accuracy. By conducting the optimized hyperparameters into the LSTM model, the daily oil production rate can be forecasted well. After training and predicting on existing production data, three different methods were used to forecast daily oil production for the next 300 days. The results were then validated using numerical simulations to compare the forecasting of LSTM and SA-LSTM. The results show that SA-LSTM can more efficiently and accurately predict daily oil production. The fitting accuracies of the three methods are as follows: numerical reservoir simulation (96.2%), LSTM (98.1%), and SA-LSTM (98.7%). The effectiveness of SA-LSTM in production rate is particularly outstanding. Using the same SA-LSTM model, we input the daily oil production data of twenty oil wells in the same block and make production prediction, and the effect is remarkable.The forecasting of the oil and gas production rate is one of the most important and effective evaluation indicators for measuring the success of reservoir development, and it plays a crucial role in dynamically predicting the oil and gas production rate during the development process. However, due to the geological factors of the reservoir and the construction factors during the development process, oil and gas production rate forecasting has become more complex, and the dynamic characteristics cannot be well described, resulting in the subsequent production rate forecasting being affected [1-4]. There are various methods for forecasting oil and gas production rate, including the Arps decline method explored by the production rate decline law, the analytical model method based on the permeability law and the material balance equation, and the numerical simulation method based on the geological model constructed using geological data [5, 6]. Conventional oil and gas production rate dynamic forecasting generally uses numerical simulation methods, which can comprehensively consider various geological factors, wellbore interference, and the impact of multiphase flow on oil and gas well production rate. However, for unconventional reservoirs such as tight oil res
{"title":"Oil Production Rate Forecasting by SA-LSTM Model in Tight Reservoirs","authors":"Denghui He, Yaguang Qu, Guanglong Sheng, Bin Wang, Xu Yan, Zhen Tao, Meng Lei","doi":"10.2113/2024/lithosphere_2023_197","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_197","url":null,"abstract":"The accurate forecasting of oil field production rate is a crucial indicator for each oil field’s successful development, but due to the complicated reservoir conditions and unknown underground environment, the high accuracy of production rate forecasting is a popular challenge. To find a low time consumption and high accuracy method for forecasting production rate, the current paper proposes a hybrid model, Simulated Annealing Long Short-Term Memory network (SA-LSTM), based on the daily oil production rate of tight reservoirs with the in situ data of injection and production rates in fractures. Furthermore, forecasting results are compared with the numerical simulation model output. The LSTM can effectively learn time-sequence problems, while SA can optimize the hyperparameters (learning rate, batch size, and decay rate) in LSTM to achieve higher accuracy. By conducting the optimized hyperparameters into the LSTM model, the daily oil production rate can be forecasted well. After training and predicting on existing production data, three different methods were used to forecast daily oil production for the next 300 days. The results were then validated using numerical simulations to compare the forecasting of LSTM and SA-LSTM. The results show that SA-LSTM can more efficiently and accurately predict daily oil production. The fitting accuracies of the three methods are as follows: numerical reservoir simulation (96.2%), LSTM (98.1%), and SA-LSTM (98.7%). The effectiveness of SA-LSTM in production rate is particularly outstanding. Using the same SA-LSTM model, we input the daily oil production data of twenty oil wells in the same block and make production prediction, and the effect is remarkable.The forecasting of the oil and gas production rate is one of the most important and effective evaluation indicators for measuring the success of reservoir development, and it plays a crucial role in dynamically predicting the oil and gas production rate during the development process. However, due to the geological factors of the reservoir and the construction factors during the development process, oil and gas production rate forecasting has become more complex, and the dynamic characteristics cannot be well described, resulting in the subsequent production rate forecasting being affected [1-4]. There are various methods for forecasting oil and gas production rate, including the Arps decline method explored by the production rate decline law, the analytical model method based on the permeability law and the material balance equation, and the numerical simulation method based on the geological model constructed using geological data [5, 6]. Conventional oil and gas production rate dynamic forecasting generally uses numerical simulation methods, which can comprehensively consider various geological factors, wellbore interference, and the impact of multiphase flow on oil and gas well production rate. However, for unconventional reservoirs such as tight oil res","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"21 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139462812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-12DOI: 10.2113/2024/lithosphere_2023_234
Heng Liu, Lei Liu, Dexian Zhang, Inkyeong Moon, M. Santosh, Yanyan Zhou, Tianyang Hu, Shisheng Kang
The 2.45–2.20 Ga period during the early Paleoproterozoic era is considered to have witnessed a global “Tectono-Magmatic Lull (TML)” and thus marks a relatively quiescent period. Our study unveils a 2.45–2.20 Ga magmatic suite from the Xiong’ershan area in the southern North China Craton, offering some key constraints on localized active tectonics during the TML. Zircon U-Pb dating shows Paleoproterozoic ages for the meta-basalt (2.31, 2.28 Ga), Na-rich meta-andesite (~2.33 Ga), tonalite-trondhjemite-granodiorite (TTG) gneisses (2.36, 2.30 Ga), K-rich granodiorite (~2.29 Ga), and monzogranite (2.33, 2.27 Ga). The meta-basalts geochemically and petrographically belong to calc-alkaline basalts and show distinctive Nb, Ta, and Ti contents and primitive mantle normalized patterns from different places in the Xiong’ershan area. Combined with their enriched εHf(t) values, the magmas were derived from subduction-related enriched mantle sources within a convergent plate boundary. The meta-andesites display high MgO content (average 4.5 wt%) and Mg# (44–57), strongly fractionated rare-earth pattern, calc-alkaline affinity, and negative Nb, Ta, and Ti anomalies. The TTG gneisses are of high SiO2 type (>62 wt%), high (La/Yb)N (17.5, 39.2), and Sr/Y (50.2, 104.3) and mostly display positive Eu anomalies and high-pressure type. Zircons from these rocks show a relatively narrow range of δ18O isotope values (5.35‰, 6.79‰) with εHf(t) isotope characteristics (−9.3, −3.3), suggesting derivation from partial melting of a thickened mafic lower crust. The youngest K-rich granodiorite and monzogranite show high K2O/Na2O ratios (0.65, 2.45). Variable molar ratio Al2O3/(CaO+Na2O+K2O) (A/CNK) and low zircon εHf(t) values suggest that the K-rich granitoids formed from the partial melting of different levels of crust. The presence of meta-basalt to andesite assemblages and diverse intermediate to felsic magmatic rocks implies magmatic activity within a convergent plate boundary tectonic environment with potential influence from plume-triggered extensional processes, supported by evidence of slab rollback and upwelling of mantle material.After 2.5 Ga, the globe has witnessed a relatively quiescent period for over 200 million years in terms of active plate tectonics, referred to as the “Tectono-Magmatic Lull (TML, 2.45–2.20 Ga),” with no significant continental crust growth or major orogenesis [1-6]. In this regard of the geological processes of TML, Silver and Behn [7] suggested stagnation of the global subduction system leading to a decrease in volcanic activity and continental growth, Condie et al. [1] referred to unusual period as a crustal age gap, while Spencer et al. [8] referred to it as a TML. At the Archean/Proterozoic boundary (2.50 Ga), the Earth underwent significant episodic evolution and transformation in the early Paleoproterozoic period [1, 9, 10].There are controversial opinions about the tectonic evolution of the Precambrian era. Cawood et al. [11], Palin
{"title":"Chronological, Petrogenetic, and Tectonic Significance of Paleoproterozoic Continental Crust within the North China Craton during the Global Tectono-Magmatic Lull","authors":"Heng Liu, Lei Liu, Dexian Zhang, Inkyeong Moon, M. Santosh, Yanyan Zhou, Tianyang Hu, Shisheng Kang","doi":"10.2113/2024/lithosphere_2023_234","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_234","url":null,"abstract":"The 2.45–2.20 Ga period during the early Paleoproterozoic era is considered to have witnessed a global “Tectono-Magmatic Lull (TML)” and thus marks a relatively quiescent period. Our study unveils a 2.45–2.20 Ga magmatic suite from the Xiong’ershan area in the southern North China Craton, offering some key constraints on localized active tectonics during the TML. Zircon U-Pb dating shows Paleoproterozoic ages for the meta-basalt (2.31, 2.28 Ga), Na-rich meta-andesite (~2.33 Ga), tonalite-trondhjemite-granodiorite (TTG) gneisses (2.36, 2.30 Ga), K-rich granodiorite (~2.29 Ga), and monzogranite (2.33, 2.27 Ga). The meta-basalts geochemically and petrographically belong to calc-alkaline basalts and show distinctive Nb, Ta, and Ti contents and primitive mantle normalized patterns from different places in the Xiong’ershan area. Combined with their enriched εHf(t) values, the magmas were derived from subduction-related enriched mantle sources within a convergent plate boundary. The meta-andesites display high MgO content (average 4.5 wt%) and Mg# (44–57), strongly fractionated rare-earth pattern, calc-alkaline affinity, and negative Nb, Ta, and Ti anomalies. The TTG gneisses are of high SiO2 type (>62 wt%), high (La/Yb)N (17.5, 39.2), and Sr/Y (50.2, 104.3) and mostly display positive Eu anomalies and high-pressure type. Zircons from these rocks show a relatively narrow range of δ18O isotope values (5.35‰, 6.79‰) with εHf(t) isotope characteristics (−9.3, −3.3), suggesting derivation from partial melting of a thickened mafic lower crust. The youngest K-rich granodiorite and monzogranite show high K2O/Na2O ratios (0.65, 2.45). Variable molar ratio Al2O3/(CaO+Na2O+K2O) (A/CNK) and low zircon εHf(t) values suggest that the K-rich granitoids formed from the partial melting of different levels of crust. The presence of meta-basalt to andesite assemblages and diverse intermediate to felsic magmatic rocks implies magmatic activity within a convergent plate boundary tectonic environment with potential influence from plume-triggered extensional processes, supported by evidence of slab rollback and upwelling of mantle material.After 2.5 Ga, the globe has witnessed a relatively quiescent period for over 200 million years in terms of active plate tectonics, referred to as the “Tectono-Magmatic Lull (TML, 2.45–2.20 Ga),” with no significant continental crust growth or major orogenesis [1-6]. In this regard of the geological processes of TML, Silver and Behn [7] suggested stagnation of the global subduction system leading to a decrease in volcanic activity and continental growth, Condie et al. [1] referred to unusual period as a crustal age gap, while Spencer et al. [8] referred to it as a TML. At the Archean/Proterozoic boundary (2.50 Ga), the Earth underwent significant episodic evolution and transformation in the early Paleoproterozoic period [1, 9, 10].There are controversial opinions about the tectonic evolution of the Precambrian era. Cawood et al. [11], Palin","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"41 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140072420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-12DOI: 10.2113/2024/lithosphere_2023_275
Mingtao Jia, Quan Jiang, Qi Xu, Xuebin Su
To investigate the impact of hydraulic conditions on the seepage characteristics of loose sandstone, this study employed optimized methods to prepare loose sandstone samples. Subsequently, seepage experiments were conducted under different injection pressures, flow rates, and flow volumes. The permeability, porosity, particle size distribution, and other parameters of the rock samples were obtained. By analyzing the response of seepage characteristics to pore and particle size characteristics, the influence of different hydraulic conditions on the seepage characteristics of loose sandstone was explored. The results indicated that improvements in the parameters of hydraulic conditions had different effects on various rock samples. For rock samples with developed seepage channels, increasing the value of each hydraulic condition parameter could expand the channels and discharge particles, and improve permeability. For rock samples with a larger number of small pores, increasing each hydraulic condition parameter caused particles to crack under pressure, drove particles to block holes, and thus reduced permeability. In this experiment, the permeability parameter had a significant positive response to the proportion of pores larger than 0.1 µm and a significant negative response to the proportion of particles smaller than 150 µm.In the fields of oil extraction and solution mining, loose sandstone is a common resource-bearing rock mass, and the seepage characteristics of this type of rock are directly related to the process design and efficiency of resource extraction [1-5]. During the processes of extraction and injection in rock formations, problems often occur, such as increased rock permeability leading to imbalanced extraction and injection or decreased permeability leading to low mining efficiency [6-8]. In the above situations, a common countermeasure in industrial practice is to use agents or equipment to adjust the permeability of rock strata to improve production. For example, in oil exploitation, dispersed gel particles with a certain particle size are used to temporarily plug the high permeability area to better drive the production of the reservoir [9, 10], and unblocking agents are used in situ to unblock clogged channels to improve the efficiency of uranium leaching [11-13]. Implementation of the above methods provides immediate improvement in the seepage effect, and the cost can be controlled, effectively solving problems related to abnormal seepage in rock formations. However, it is important to note that while the solutions for abnormal seepage are relatively effective, they are still confined to a reactive, postevent stage. The time and costs associated with these solutions continue to impede the enhancement of production efficiency. The objective of this study is to address these issues by starting from the mechanisms of permeability changes. It delves into the influence of hydraulic conditions on the seepage characteristics of loo
孔隙分布特征参数可以有效揭示岩石的孔隙发育与渗流情况，并据此推导出渗流特征的变化特征与机理[26-29]，而颗粒特征的分析则侧重于粒度分布对孔隙结构的影响以及游离颗粒对渗流通道的影响[29, 30]。研究表明，孔隙特征和颗粒特征基本上决定了岩石的渗透性，而且这两种特征是相互关联的[31]。因此，将对岩石孔隙分布和粒径分布特征的研究与从微观角度进行的渗流实验相结合，可以充分揭示松散砂岩的水力条件与渗流特征之间的关系。然而，在实验室中，由于松散砂岩独特的岩性特征，对其渗流特征的微观研究明显不足。松散砂岩的内聚力主要来自非饱和岩粒以及细粒土之间的毛细作用 [32，33]。这种作用力稳定性差，在饱和状态下就会失效，因此松散砂岩很难切割成型，岩石颗粒在水中容易崩解扩散，破坏渗水管道。此外，天然松散砂岩由于颗粒分布随机性大，容易产生较大的实验误差。因此，在实验室中对松散砂岩进行的渗流实验很少。一些学者采用数值模拟或大型岩样整体渗流的方法来获取渗流特性的变化[34-38]。但这类方法只能用于评价渗透率变化等参数，无法直观地获得实验前后的孔隙度、颗粒分布等关键参数，难以解释松散砂岩渗流特性变化的原理。近年来，一些研究采用侧向包裹或特殊固定装置保护松散砂岩样品[39-41]，成功实现了小规模渗流实验，其岩样保护方法值得借鉴。但从相关研究的数据来看，这些实验的成功得益于砂岩样品的良好完整性。但这些实验后，岩样的渗出端出现了明显的颗粒剥落现象，导致实验误差较大，难以进行更多的实验。为了研究不同水力条件影响松散砂岩孔隙度和颗粒特征，进而改变其渗流特性的规律和机理，设计了一种特殊的优化松散砂岩制备方法，用于制备岩石样品。在不同注入压力、流速和流量条件下，对岩石样本进行了渗流实验。实验前后通过渗流仪、核磁共振波谱仪、粒度分布仪等仪器获得了渗透率、孔隙度、粒度分布等关键参数，并综合分析了水力条件、渗流特征、孔隙度分布特征、粒度分布特征的响应和原理。最后，总结了不同水力条件对松散砂岩渗流特征的影响关系和影响原理，为工程实践提供了理论参考，有助于提高含松散砂岩资源渗流相关作业的效率。本实验中，松散砂岩样品 A 和 B 分别取自新疆 A 型铀矿地下 400 米地层和内蒙古 B 型铀矿地下 500 米地层。两种岩石样品的矿物相显微鉴定结果见表 1。样品 A 的干密度为 1.69 g/cm³，样品 B 的干密度为 1.62 g/cm³。渗流实验采用海安县石油科学研究仪器有限公司生产的 HKY-1 长芯渗流监测仪进行，如图 2（a）所示。
{"title":"Influence of Hydraulic Conditions on Seepage Characteristics of Loose Sandstone","authors":"Mingtao Jia, Quan Jiang, Qi Xu, Xuebin Su","doi":"10.2113/2024/lithosphere_2023_275","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_275","url":null,"abstract":"To investigate the impact of hydraulic conditions on the seepage characteristics of loose sandstone, this study employed optimized methods to prepare loose sandstone samples. Subsequently, seepage experiments were conducted under different injection pressures, flow rates, and flow volumes. The permeability, porosity, particle size distribution, and other parameters of the rock samples were obtained. By analyzing the response of seepage characteristics to pore and particle size characteristics, the influence of different hydraulic conditions on the seepage characteristics of loose sandstone was explored. The results indicated that improvements in the parameters of hydraulic conditions had different effects on various rock samples. For rock samples with developed seepage channels, increasing the value of each hydraulic condition parameter could expand the channels and discharge particles, and improve permeability. For rock samples with a larger number of small pores, increasing each hydraulic condition parameter caused particles to crack under pressure, drove particles to block holes, and thus reduced permeability. In this experiment, the permeability parameter had a significant positive response to the proportion of pores larger than 0.1 µm and a significant negative response to the proportion of particles smaller than 150 µm.In the fields of oil extraction and solution mining, loose sandstone is a common resource-bearing rock mass, and the seepage characteristics of this type of rock are directly related to the process design and efficiency of resource extraction [1-5]. During the processes of extraction and injection in rock formations, problems often occur, such as increased rock permeability leading to imbalanced extraction and injection or decreased permeability leading to low mining efficiency [6-8]. In the above situations, a common countermeasure in industrial practice is to use agents or equipment to adjust the permeability of rock strata to improve production. For example, in oil exploitation, dispersed gel particles with a certain particle size are used to temporarily plug the high permeability area to better drive the production of the reservoir [9, 10], and unblocking agents are used in situ to unblock clogged channels to improve the efficiency of uranium leaching [11-13]. Implementation of the above methods provides immediate improvement in the seepage effect, and the cost can be controlled, effectively solving problems related to abnormal seepage in rock formations. However, it is important to note that while the solutions for abnormal seepage are relatively effective, they are still confined to a reactive, postevent stage. The time and costs associated with these solutions continue to impede the enhancement of production efficiency. The objective of this study is to address these issues by starting from the mechanisms of permeability changes. It delves into the influence of hydraulic conditions on the seepage characteristics of loo","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"174 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139589630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-12DOI: 10.2113/2024/lithosphere_2023_297
Fei Xue, Fan Yang, Weidong Ren, M. Santosh, Zesheng Qian, Yin Huang, Zijian Tan
The North Qilian Orogen witnessed the opening, subduction, and closure of the Proto-Tethys Qilian Ocean and the post-subduction of multiple exhumation events from Late Neoproterozoic to Early Paleozoic. The Early Paleozoic dioritic–granitic magmatic suites, prominently exposed in the eastern North Qilian Orogen, offer valuable insights into the evolution of the Proto-Tethys Ocean. However, their petrogenesis, magma source, and tectonic evolution remain controversial. Here, we investigate the Leigongshan, Zhigou, and Dalongcun intrusions and present geochronological, geochemical, and isotopic data, aiming to refine the comprehension of their timing and petrogenesis, which will contribute to understanding the tectonic evolution of the Proto-Tethys Ocean. Zircon U-Pb dating reveals mean ages of 471–427 Ma for these intrusions, consistent with compiled formation ages of dioritic–granitic intrusions in the eastern North Qilian Orogen, indicating close temporal links with the tectonic evolution of the Proto-Tethys Ocean during the Early Paleozoic. The studied magmatic rocks could be categorized into two major types: granitoids and diorites. The granitoids are majorly I-type granitoids that are generated through partial melting of the mafic lower crust and fractional crystallization at the middle-upper crust, with the involvement of mantle-derived materials. The diorites underwent limited crustal contamination and fractionation of hornblende, plagioclase, and some accessory minerals. They were derived mainly from the mixture of fertile mantle and reworked crustal components, with minor contributions from subduction-related slab fluids and sediment melts. In addition, all the studied Early Paleozoic dioritic–granitic intrusions (ca. 471–427 Ma) formed within subduction-related arc settings. Combined with the tectonic evolution of the Early Paleozoic Qilian orogenic system, we interpret these Cambrian to Silurian dioritic–granitic intrusions as tectonic responses to the subduction (ca. 520–460 Ma) and closure (~440 Ma) of the Proto-Tethys Ocean, whereas the Devonian Huangyanghe intrusion witnessed the final stage of extensional collapse of the Qilian orogenic system at ca. 400–360 Ma.The Tethyan orogenic belt, a significant continent–continent collisional belt in the world, preserves records of oceanic subduction, continental collision, and extensional collapse [1-3]. This belt is divided into the Proto-Tethys (Early Paleozoic), the Paleo-Tethys (Late Paleozoic-Early Mesozoic), and the Neo-Tethys (Late Mesozoic-Cenozoic) stages [4-6]. Originating from the breakup of the Rodinia supercontinent, the Proto-Tethys continued to expand in the Cambrian [3]. Subsequently, the Proto-Tethys started to shrink and closed during the assembly of North China and Siberia–Kazakhstan Cratons during the Late Silurian [7]. The Qilian orogenic belt is the pivotal segment of the Central China Orogen and witnessed the subduction and collision processes during the closure of the
{"title":"Petrogenesis of the Early Paleozoic Dioritic–Granitic Magmatism in the Eastern North Qilian Orogen, NW China: Implications for Tethyan Tectonic Evolution","authors":"Fei Xue, Fan Yang, Weidong Ren, M. Santosh, Zesheng Qian, Yin Huang, Zijian Tan","doi":"10.2113/2024/lithosphere_2023_297","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_297","url":null,"abstract":"The North Qilian Orogen witnessed the opening, subduction, and closure of the Proto-Tethys Qilian Ocean and the post-subduction of multiple exhumation events from Late Neoproterozoic to Early Paleozoic. The Early Paleozoic dioritic–granitic magmatic suites, prominently exposed in the eastern North Qilian Orogen, offer valuable insights into the evolution of the Proto-Tethys Ocean. However, their petrogenesis, magma source, and tectonic evolution remain controversial. Here, we investigate the Leigongshan, Zhigou, and Dalongcun intrusions and present geochronological, geochemical, and isotopic data, aiming to refine the comprehension of their timing and petrogenesis, which will contribute to understanding the tectonic evolution of the Proto-Tethys Ocean. Zircon U-Pb dating reveals mean ages of 471–427 Ma for these intrusions, consistent with compiled formation ages of dioritic–granitic intrusions in the eastern North Qilian Orogen, indicating close temporal links with the tectonic evolution of the Proto-Tethys Ocean during the Early Paleozoic. The studied magmatic rocks could be categorized into two major types: granitoids and diorites. The granitoids are majorly I-type granitoids that are generated through partial melting of the mafic lower crust and fractional crystallization at the middle-upper crust, with the involvement of mantle-derived materials. The diorites underwent limited crustal contamination and fractionation of hornblende, plagioclase, and some accessory minerals. They were derived mainly from the mixture of fertile mantle and reworked crustal components, with minor contributions from subduction-related slab fluids and sediment melts. In addition, all the studied Early Paleozoic dioritic–granitic intrusions (ca. 471–427 Ma) formed within subduction-related arc settings. Combined with the tectonic evolution of the Early Paleozoic Qilian orogenic system, we interpret these Cambrian to Silurian dioritic–granitic intrusions as tectonic responses to the subduction (ca. 520–460 Ma) and closure (~440 Ma) of the Proto-Tethys Ocean, whereas the Devonian Huangyanghe intrusion witnessed the final stage of extensional collapse of the Qilian orogenic system at ca. 400–360 Ma.The Tethyan orogenic belt, a significant continent–continent collisional belt in the world, preserves records of oceanic subduction, continental collision, and extensional collapse [1-3]. This belt is divided into the Proto-Tethys (Early Paleozoic), the Paleo-Tethys (Late Paleozoic-Early Mesozoic), and the Neo-Tethys (Late Mesozoic-Cenozoic) stages [4-6]. Originating from the breakup of the Rodinia supercontinent, the Proto-Tethys continued to expand in the Cambrian [3]. Subsequently, the Proto-Tethys started to shrink and closed during the assembly of North China and Siberia–Kazakhstan Cratons during the Late Silurian [7]. The Qilian orogenic belt is the pivotal segment of the Central China Orogen and witnessed the subduction and collision processes during the closure of the","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":"13 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139951432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-12DOI: 10.2113/2024/lithosphere_2023_211
Shida Song, Zhiyuan He, Wenbo Su, Linglin Zhong, Kanghui Zhong, Stijn Glorie, Yifan Song, Johan De Grave
The Tibetan Plateau is currently the widest and highest elevation orogenic plateau on Earth. It formed as a response to the Cenozoic and is still ongoing collision between the Indian and Eurasian plates. The Xigaze fore-arc basin distributed along the Indus–Yarlung suture zone in southern Tibet preserves important information related to the late Cenozoic tectonic and topographic evolution of the plateau. In this study, apatite fission track (AFT) thermochronology was carried out on twelve sandstone samples from the middle segment of the Xigaze basin and additionally on four sedimentary rocks from the neighboring Dazhuka (Kailas) and Liuqu Formations. Inverse thermal history modeling results reveal that the fore-arc basin rocks experienced episodic late Oligocene to Miocene enhanced cooling. Taking into account regional geological data, it is suggested that the late Oligocene-early Miocene (~27–18 Ma) cooling recognized in the northern part of the basin was promoted by fault activity along the Great Counter thrust, while mid-to-late Miocene-accelerated exhumation was facilitated by strong incision of the Yarlung and Buqu rivers, which probably resulted from enhanced East Asian summer monsoon precipitation. Sandstone and conglomerate samples from the Dazhuka and Liuqu Formations yielded comparable Miocene AFT apparent ages to those of the Xigaze basin sediments, indicative of (mid-to-late Miocene) exhumation soon after their early Miocene burial (> ~3–4 km). Additionally, our new and published low-temperature thermochronological data indicate that enhanced basement cooling during the Miocene prevailed in vast areas of central southern Tibet when regional exhumation was triggered by both tectonic and climatic contributing factors. This recent and widespread regional exhumation also led to the formation of the high-relief topography of the external drainage area in southern Tibet, including the Xigaze fore-arc basin.Orogenic belts are dominant topographic features on Earth and are characterized by high tectonic activity and high elevations. They provide the best natural laboratory to study the coupling between tectonics, erosion, and climate [1-4]. In these regions, negative feedback between fast denudation and high elevation causes enhanced erosion that, in turn, tends to reduce the topography. The collision between India and Asia led to the formation of the Tibetan Plateau, which stands ~4–5 km high over a region of ~3 million km2 (Figures 1(a) and (b)). The southern Tibetan Plateau (i.e., the southern Lhasa terrane—Tethyan Himalaya) is characterized by a high-elevation and low-relief landscape (i.e., “flat” highland) [5]. Structurally, several ~E–W trending large-scale thrust faults and a series of ~N–S striking normal faults are well developed in the southern Lhasa terrane [6-8]. Furthermore, the west-to-east flowing Yarlung river runs through the southern Tibetan Plateau, its source is high in western Tibet, and it cuts through the Namche Barwa
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