Introduction: The early Jurassic granitoids in the Qinling Orogenic Belt (QOB) play a crucial role in understanding the tectonic implications for the geological evolution of China. To elucidate the early Jurassic tectonic setting of QOB, we performed a comprehensive analysis of zircon U-Pb ages, whole-rock geochemistry, and in situ zircon Lu-Hf isotopes from early Jurassic monzodiorite and Kfeldspar granite within the Baoji batholith in western QOB.Geochronology Method and Results: The intrusions yielded zircon U-Pb ages of 186 ± 2 Ma and 188 ± 2 Ma, respectively.Geochemistry Results: The monzodiorites are characterized by relatively high MgO, Rb, Th, U, and LREE contents, as well as low P, Ti, and HREE contents. They also exhibit high Nb/Ta ratios (20.6–23.4). The zircon εHf(t) values for the monzodiorite sample range from −4.36 to 6.47, indicating significant contributions from a fertile continental lithospheric mantle with the involvement of crustal components. The K-feldspar granites are enriched in K2O+ Na2O, Rb, Zr, Hf, and Nb, and lower Ba, Sr, Ti, and P. They exhibit high Nb/Ta and Ga/Al ratios but low Y/Nb and Yb/Ta ratios. Their geochemical characteristics reveal an A-type granite affinity with elevated zircon saturation temperatures (848°C–900 °C). Additionally, the K-feldspar granite exhibits REE and trace element patterns similar to those observed in the monzodiorite. However, a wide range of zircon εHf(t) values (−4.72 to 3.98), differing from those of the monzodiorite, indicate that the parental magma of the K-feldspar granite experienced magma mixing between a monzodioritic magma and a crustal-derived felsic magma.Discussion: These findings suggest that both A-type K-feldspar granite and monzodiorite likely formed during post-orogenic processes. Additionally, the QOB commenced its postorogenic evolution as an extensional tectonic environment during the early Jurassic period.
{"title":"Early Jurassic A-type granite and monzodiorite from the Baoji batholith: Implication for tectonic transition from post-collision to post-orogenic extension in the Qinling Orogenic Belt, China","authors":"Xiangkuan Gong, Nijiati Abuduxun, Xiaoliang Jia, Yuanfeng Cheng, Hongming Cai, Xueqian Wu, Haodong Yang","doi":"10.3389/feart.2024.1428055","DOIUrl":"https://doi.org/10.3389/feart.2024.1428055","url":null,"abstract":"Introduction: The early Jurassic granitoids in the Qinling Orogenic Belt (QOB) play a crucial role in understanding the tectonic implications for the geological evolution of China. To elucidate the early Jurassic tectonic setting of QOB, we performed a comprehensive analysis of zircon U-Pb ages, whole-rock geochemistry, and <jats:italic>in situ</jats:italic> zircon Lu-Hf isotopes from early Jurassic monzodiorite and Kfeldspar granite within the Baoji batholith in western QOB.Geochronology Method and Results: The intrusions yielded zircon U-Pb ages of 186 ± 2 Ma and 188 ± 2 Ma, respectively.Geochemistry Results: The monzodiorites are characterized by relatively high MgO, Rb, Th, U, and LREE contents, as well as low P, Ti, and HREE contents. They also exhibit high Nb/Ta ratios (20.6–23.4). The zircon <jats:italic>ε</jats:italic><jats:sub>Hf</jats:sub>(<jats:italic>t</jats:italic>) values for the monzodiorite sample range from −4.36 to 6.47, indicating significant contributions from a fertile continental lithospheric mantle with the involvement of crustal components. The K-feldspar granites are enriched in K<jats:sub>2</jats:sub>O+ Na<jats:sub>2</jats:sub>O, Rb, Zr, Hf, and Nb, and lower Ba, Sr, Ti, and P. They exhibit high Nb/Ta and Ga/Al ratios but low Y/Nb and Yb/Ta ratios. Their geochemical characteristics reveal an A-type granite affinity with elevated zircon saturation temperatures (848°C–900 °C). Additionally, the K-feldspar granite exhibits REE and trace element patterns similar to those observed in the monzodiorite. However, a wide range of zircon <jats:italic>ε</jats:italic><jats:sub>Hf</jats:sub>(<jats:italic>t</jats:italic>) values (−4.72 to 3.98), differing from those of the monzodiorite, indicate that the parental magma of the K-feldspar granite experienced magma mixing between a monzodioritic magma and a crustal-derived felsic magma.Discussion: These findings suggest that both A-type K-feldspar granite and monzodiorite likely formed during post-orogenic processes. Additionally, the QOB commenced its postorogenic evolution as an extensional tectonic environment during the early Jurassic period.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-03DOI: 10.3389/feart.2024.1277642
E. J. Biebesheimer, M. B. Suarez
Introduction: The Yucca Formation is a Lower Cretaceous sedimentary unit present in West Texas. Based on its relative stratigraphic position in the Cretaceous succession of West Texas, it is expected that the Yucca Formation is of Albian and/or Aptian age. It is also expected that the carbon isotope excursions associated with OAE 1a and OAE 1b should be identified in the Yucca Formation. The goals of this project are to 1. construct a carbon isotope chemostratigraphic record of the Yucca Formation, and 2. correlate the Yucca Formation with strata of similar age using chemostratigraphy.Methods: 163 samples were collected from Big Bend Ranch State Park (BBRSP) to determine the δ13C value of bulk sedimentary organic matter.Results: C-isotope values range from −27.02‰ to −18.42‰.Discussion: Carbon isotope excursions (CIEs) that are associated with the Aptian-Albian Boundary are identified as well as CIEs associated with Oceanic Anoxic Events (1a and 1b). This allows us to conclude that the Aptian-Albian boundary is recorded within the Yucca Formation strata at about 71 m above the base of the section exposed in the Lower Shutup of the Solitario in Big Bend Ranch State Park. Regional correlation of the Yucca Formation to other chemostratigraphic records from other Cretaceous strata suggests that the Yucca Formation in BBRSP is time equivalent to the Sligo, Pine Island, James, Bexar, and a portion of the lower Glen Rose Formation on the Comanche Platform and to a portion of the lower Glen Rose Formation in Big Bend National Park.
{"title":"Carbon isotope chemostratigraphy of the Yucca Formation from the Solitario, Big Bend Ranch State Park, Texas","authors":"E. J. Biebesheimer, M. B. Suarez","doi":"10.3389/feart.2024.1277642","DOIUrl":"https://doi.org/10.3389/feart.2024.1277642","url":null,"abstract":"Introduction: The Yucca Formation is a Lower Cretaceous sedimentary unit present in West Texas. Based on its relative stratigraphic position in the Cretaceous succession of West Texas, it is expected that the Yucca Formation is of Albian and/or Aptian age. It is also expected that the carbon isotope excursions associated with OAE 1a and OAE 1b should be identified in the Yucca Formation. The goals of this project are to 1. construct a carbon isotope chemostratigraphic record of the Yucca Formation, and 2. correlate the Yucca Formation with strata of similar age using chemostratigraphy.Methods: 163 samples were collected from Big Bend Ranch State Park (BBRSP) to determine the δ<jats:sup>13</jats:sup>C value of bulk sedimentary organic matter.Results: C-isotope values range from −27.02‰ to −18.42‰.Discussion: Carbon isotope excursions (CIEs) that are associated with the Aptian-Albian Boundary are identified as well as CIEs associated with Oceanic Anoxic Events (1a and 1b). This allows us to conclude that the Aptian-Albian boundary is recorded within the Yucca Formation strata at about 71 m above the base of the section exposed in the Lower Shutup of the Solitario in Big Bend Ranch State Park. Regional correlation of the Yucca Formation to other chemostratigraphic records from other Cretaceous strata suggests that the Yucca Formation in BBRSP is time equivalent to the Sligo, Pine Island, James, Bexar, and a portion of the lower Glen Rose Formation on the Comanche Platform and to a portion of the lower Glen Rose Formation in Big Bend National Park.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-02DOI: 10.3389/feart.2024.1415276
Lu Kaidong, Cui Tingting, Wang Yintang, Liu Yong
Precipitation and incoming water are the key contributing factors to local flooding events, and analyzing the intra-annual distribution and change characteristics of precipitation and incoming water will be beneficial to the understanding of flooding contributing factors in this region. In this paper, the characteristics of intra-annual distribution of precipitation and incoming water and the synchronization of their changes in the lower reaches of the Yangtze River Basin (LYRB) from 1980 to 2020 are studied using the concentration degree and concentration period as quantitative indicators. The results are as follows: 1) the maximum precipitation occurs earlier in the year, while maximum incoming water occurs with little variation in timing but significant variation in total volume; 2) the concentration degree of both precipitation and incoming water show a slowly decreasing trend. The concentration period of precipitation is slightly advanced, and that of incoming water is significantly delayed; 3) the occurrence time and concentration period of the incoming water peak during 2010–2020 lagged behind that of precipitation, which played a role in suppressing the occurrence of floods in the LYRB. This study can provide a scientific basis for the future supply and demand of water resources in the LYRB for safe use.
{"title":"Characteristics of intra-annual distribution of precipitation and incoming water and the synchronization analysis of their changes in the lower reaches of the Yangtze river basin","authors":"Lu Kaidong, Cui Tingting, Wang Yintang, Liu Yong","doi":"10.3389/feart.2024.1415276","DOIUrl":"https://doi.org/10.3389/feart.2024.1415276","url":null,"abstract":"Precipitation and incoming water are the key contributing factors to local flooding events, and analyzing the intra-annual distribution and change characteristics of precipitation and incoming water will be beneficial to the understanding of flooding contributing factors in this region. In this paper, the characteristics of intra-annual distribution of precipitation and incoming water and the synchronization of their changes in the lower reaches of the Yangtze River Basin (LYRB) from 1980 to 2020 are studied using the concentration degree and concentration period as quantitative indicators. The results are as follows: 1) the maximum precipitation occurs earlier in the year, while maximum incoming water occurs with little variation in timing but significant variation in total volume; 2) the concentration degree of both precipitation and incoming water show a slowly decreasing trend. The concentration period of precipitation is slightly advanced, and that of incoming water is significantly delayed; 3) the occurrence time and concentration period of the incoming water peak during 2010–2020 lagged behind that of precipitation, which played a role in suppressing the occurrence of floods in the LYRB. This study can provide a scientific basis for the future supply and demand of water resources in the LYRB for safe use.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-02DOI: 10.3389/feart.2024.1399095
Li-Ping Guo, Xin-Bao Gu
Accurate evaluation of surrounding rock quality grade can help guarantee the safety of tunnel design and construction; hence, it has great significance in the construction of mine shafts. Accordingly, the uniaxial saturated compressive strength of the rock block Rc, rock quality index RQD, rock softening coefficient kR, integrity coefficient of the rock mass kv, depth H, unit weight of the rock mass γ, coefficient of quantification of the angle between the principal structural plane and shaft axis k2, and weight of the groundwater k1 are first selected as the indexes of assessment to introduce the game gray target model. Then, the gray target model of the surrounding rocks in a mine shaft project is established. The weight coefficient of each index is next calculated using the combination weighting method based on game theory, and the synthetic target center distance of each sample is determined using the gray target model. Finally, the quality level of the asphalt pavement is determined. The suggested model can be used to mine a small data sample to the maximum extent possible, thereby minimizing the information shortage caused by the small sample to a certain extent, to evaluate the final quality grade of the surrounding rocks quantitatively. Thus, the proposed approach provides a new scheme for the future quality assessments of surrounding rocks.
{"title":"Quality evaluation of surrounding rocks in a mine shaft based on the game gray target model","authors":"Li-Ping Guo, Xin-Bao Gu","doi":"10.3389/feart.2024.1399095","DOIUrl":"https://doi.org/10.3389/feart.2024.1399095","url":null,"abstract":"Accurate evaluation of surrounding rock quality grade can help guarantee the safety of tunnel design and construction; hence, it has great significance in the construction of mine shafts. Accordingly, the uniaxial saturated compressive strength of the rock block <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>R</mml:mi><mml:mi mathvariant=\"normal\">c</mml:mi></mml:msub></mml:mrow></mml:math></jats:inline-formula>, rock quality index <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:mi>R</mml:mi><mml:mi>Q</mml:mi><mml:mi>D</mml:mi></mml:mrow></mml:math></jats:inline-formula>, rock softening coefficient <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mi>R</mml:mi></mml:msub></mml:mrow></mml:math></jats:inline-formula>, integrity coefficient of the rock mass <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mi>v</mml:mi></mml:msub></mml:mrow></mml:math></jats:inline-formula>, depth <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:mi>H</mml:mi></mml:mrow></mml:math></jats:inline-formula>, unit weight of the rock mass <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:mi>γ</mml:mi></mml:mrow></mml:math></jats:inline-formula>, coefficient of quantification of the angle between the principal structural plane and shaft axis <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math></jats:inline-formula>, and weight of the groundwater <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mn>1</mml:mn></mml:msub></mml:mrow></mml:math></jats:inline-formula> are first selected as the indexes of assessment to introduce the game gray target model. Then, the gray target model of the surrounding rocks in a mine shaft project is established. The weight coefficient of each index is next calculated using the combination weighting method based on game theory, and the synthetic target center distance of each sample is determined using the gray target model. Finally, the quality level of the asphalt pavement is determined. The suggested model can be used to mine a small data sample to the maximum extent possible, thereby minimizing the information shortage caused by the small sample to a certain extent, to evaluate the final quality grade of the surrounding rocks quantitatively. Thus, the proposed approach provides a new scheme for the future quality assessments of surrounding rocks.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction: The research is aimed to identify the vulnerable areas of quarry slopes through the creation of a stress-strain state model for the rock mass at the Vostochny quarry, East Saryoba field of the Zhi-landy Group of cupriferous sandstones, as well as their subsequent strengthening.Methods: The research is based on the development of a database containing information on mining-geological, geophysical, geodetic and aerospace surveys. The authors of the research use modern geodetic, aerospace and geophysical technologies for scientifically based predicting of technogenic disasters and the rock mass stress-strain state modeling to ensure safe and optimal mining of fields in difficult mining-geological conditions.Results: The results obtained show that the strengthening of weakened quarry slopes based on the rock mass stress-strain state modeling contributes to the scientific-practical profitability of field mining and provides safe mining in difficult mining-geological conditions.Discussion: Novelty is in the scientific substantiation of the method for strengthening quarry slopes, which is based on the rock mass stress-strain state modeling. The research is of great practical importance, as the rock mass stress-strain state modeling increases the reliability of predicting the rock mass state during its mining. Strengthening of quarry slopes using the proposed method reduces risks and increases safety and economic efficiency of mining the solid mineral deposits in difficult mining-geological conditions.
{"title":"Investigation of the rock mass state in the near-wall part of the quarry and its stability management","authors":"Pavlo Saik, Kanay Rysbekov, Khaini-Kamal Kassymkanova, Vasyl Lozynskyi, Guldana Kyrgizbayeva, Serik Moldabayev, Dmytro Babets, Arnat Salkynov","doi":"10.3389/feart.2024.1395418","DOIUrl":"https://doi.org/10.3389/feart.2024.1395418","url":null,"abstract":"Introduction: The research is aimed to identify the vulnerable areas of quarry slopes through the creation of a stress-strain state model for the rock mass at the Vostochny quarry, East Saryoba field of the Zhi-landy Group of cupriferous sandstones, as well as their subsequent strengthening.Methods: The research is based on the development of a database containing information on mining-geological, geophysical, geodetic and aerospace surveys. The authors of the research use modern geodetic, aerospace and geophysical technologies for scientifically based predicting of technogenic disasters and the rock mass stress-strain state modeling to ensure safe and optimal mining of fields in difficult mining-geological conditions.Results: The results obtained show that the strengthening of weakened quarry slopes based on the rock mass stress-strain state modeling contributes to the scientific-practical profitability of field mining and provides safe mining in difficult mining-geological conditions.Discussion: Novelty is in the scientific substantiation of the method for strengthening quarry slopes, which is based on the rock mass stress-strain state modeling. The research is of great practical importance, as the rock mass stress-strain state modeling increases the reliability of predicting the rock mass state during its mining. Strengthening of quarry slopes using the proposed method reduces risks and increases safety and economic efficiency of mining the solid mineral deposits in difficult mining-geological conditions.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-02DOI: 10.3389/feart.2024.1418821
Lin Zhao, Lijun Zhang, Yanchun Su, Xianhong Tan, CongCong Li, Shuoliang Wang
Using subterranean rock cores as samples, the impact of depletion exploitation and cyclic gas injection on the occurrence and dynamic utilization of condensate oil and the damage to reservoirs were studied. Initially, the internal pore structure of the rock core was analysed using computer tomography (CT), followed by depletion and cyclic gas injection experiments, with in-situ CT scanning of the samples. The results indicate that under different fracture apertures, condensate oil exhibits wave flow and slug flow states. The production effectiveness of cyclic gas injection is significantly superior to depletion exploitation production, with condensate oil saturation decreasing by over 30%. During cyclic gas injection, fractures serve as the main flow channels, with condensate oil being extracted first. In cyclic gas injection, the most significant effect is seen during the first injection, with a decrease in oil saturation of around 3%. Subsequent injections show decreases of approximately 1% and 0.5% in oil saturation respectively. As the gas injection volume increases, the extent of cumulative production rate improvement also gradually increases; however, once the injection volume reaches the reservoir pressure, the rate of cumulative production rate improvement will gradually decrease. These findings provide technical support for optimizing the development mode of condensate gas reservoirs, clarifying the seepage law of condensate oil and gas, and providing technical support for the efficient development of fractured condensate gas reservoirs.
{"title":"In-situ CT study on the effect of cyclic gas injection and depletion exploitation on the phase behavior of fractured condensate gas reservoirs","authors":"Lin Zhao, Lijun Zhang, Yanchun Su, Xianhong Tan, CongCong Li, Shuoliang Wang","doi":"10.3389/feart.2024.1418821","DOIUrl":"https://doi.org/10.3389/feart.2024.1418821","url":null,"abstract":"Using subterranean rock cores as samples, the impact of depletion exploitation and cyclic gas injection on the occurrence and dynamic utilization of condensate oil and the damage to reservoirs were studied. Initially, the internal pore structure of the rock core was analysed using computer tomography (CT), followed by depletion and cyclic gas injection experiments, with <jats:italic>in-situ</jats:italic> CT scanning of the samples. The results indicate that under different fracture apertures, condensate oil exhibits wave flow and slug flow states. The production effectiveness of cyclic gas injection is significantly superior to depletion exploitation production, with condensate oil saturation decreasing by over 30%. During cyclic gas injection, fractures serve as the main flow channels, with condensate oil being extracted first. In cyclic gas injection, the most significant effect is seen during the first injection, with a decrease in oil saturation of around 3%. Subsequent injections show decreases of approximately 1% and 0.5% in oil saturation respectively. As the gas injection volume increases, the extent of cumulative production rate improvement also gradually increases; however, once the injection volume reaches the reservoir pressure, the rate of cumulative production rate improvement will gradually decrease. These findings provide technical support for optimizing the development mode of condensate gas reservoirs, clarifying the seepage law of condensate oil and gas, and providing technical support for the efficient development of fractured condensate gas reservoirs.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-02DOI: 10.3389/feart.2024.1427426
Guanyu Zhang, Xuri Huang, Yungui Xu, Shuhang Tang, Kang Chen, Da Peng
Deep carbonate reservoirs are attractive targets for gas development. These reservoirs are deeply buried, and commonly possess strong heterogeneity and poor seismic data quality, making the identification of favorable production areas (“sweet spots”) challenging. Furthermore, sedimentary facies and fault systems markedly impact reservoir quality, and identifying these features in seismic data is also crucial for sweet spot identification. To solve these problems, we propose a dual-factor-controlled sweet spot identification method with two steps. First, sedimentary facies and faults are identified separately at different seismic scales using different attributes by the steerable pyramid (SP) method. The SP method decomposes the original seismic data into high-frequency and low-frequency data. The amplitude attributes from high-frequency data are used to identify sedimentary facies, and coherence attributes based on low-frequency data are used to characterize the fault systems. Second, after separately identifying the sedimentary facies and faults, the two attribute volumes are merged together to identify reservoir sweet spots. The results are verified by using well production data. The results of a field study in the Dengying Formation deep carbonate reservoir in the central Sichuan Basin, China, indicate that reservoir sweet spots are primarily developed in ideal sedimentary facies along strike-slip fault systems. Sedimentary facies generally control the type and distribution of reservoirs, whereas strike-slip fault systems control the migration and accumulation of gas. In addition, the fault systems serve as karst channels that further improve the reservoir properties. The proposed dual-factor method might help to maximize exploration potential in deep carbonate reservoirs with similar settings.
{"title":"Deep carbonate gas reservoir sweet spot identification with seismic data based on dual-factor control of sedimentary facies and fault system","authors":"Guanyu Zhang, Xuri Huang, Yungui Xu, Shuhang Tang, Kang Chen, Da Peng","doi":"10.3389/feart.2024.1427426","DOIUrl":"https://doi.org/10.3389/feart.2024.1427426","url":null,"abstract":"Deep carbonate reservoirs are attractive targets for gas development. These reservoirs are deeply buried, and commonly possess strong heterogeneity and poor seismic data quality, making the identification of favorable production areas (“sweet spots”) challenging. Furthermore, sedimentary facies and fault systems markedly impact reservoir quality, and identifying these features in seismic data is also crucial for sweet spot identification. To solve these problems, we propose a dual-factor-controlled sweet spot identification method with two steps. First, sedimentary facies and faults are identified separately at different seismic scales using different attributes by the steerable pyramid (SP) method. The SP method decomposes the original seismic data into high-frequency and low-frequency data. The amplitude attributes from high-frequency data are used to identify sedimentary facies, and coherence attributes based on low-frequency data are used to characterize the fault systems. Second, after separately identifying the sedimentary facies and faults, the two attribute volumes are merged together to identify reservoir sweet spots. The results are verified by using well production data. The results of a field study in the Dengying Formation deep carbonate reservoir in the central Sichuan Basin, China, indicate that reservoir sweet spots are primarily developed in ideal sedimentary facies along strike-slip fault systems. Sedimentary facies generally control the type and distribution of reservoirs, whereas strike-slip fault systems control the migration and accumulation of gas. In addition, the fault systems serve as karst channels that further improve the reservoir properties. The proposed dual-factor method might help to maximize exploration potential in deep carbonate reservoirs with similar settings.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-01DOI: 10.3389/feart.2024.1389308
Alexander S. Kshetrimayum, Pradeep K. Goswami, Chung-Pai Chang, Wu-Lung Chang, Lalit Mohan Joshi
The active tectonic aspects of the Indo-Myanmar Range (IMR) have not yet been studied in detail in spite of the fact that it’s seismically active. In the present study qualitative and quantitative geomorphic analyses have been carried out to understand the active tectonic evolution of Nungba, and Barak-Makru thrust sheets (NBTS and BMTS) in the central part of IMR. The focus of the study is on understanding the active spatial growth pattern of adjacent thrust sheets in an evolving mountain range and providing baseline data for further detailed seismotectonic and seismic hazard vulnerability analyses. Drainage characteristics, disposition of landforms and statistical analyses of Normalized Steepness Index (ksn), Hypsometric Integral (HI) and Transverse Topography Symmetry Factor (T), computed for a total of 164 4th-order drainage basins, reveal that both of these adjoining thrust sheets are actively uplifting. Higher values of ksn (mode = 111) and HI (mode = 0.46) in NBTS suggest its faster uplift than the BMTS, which has comparatively lower values of ksn (mode = 56) and HI (mode = 0.43). Moreover, the northern parts of the both the thrust sheets are uplifting faster than their southern parts due to along-strike variations in the movement on their basal thrusts, as a result of which the NBTS has been south-southeastwardly down-tilting and the BMTS is south-southwestwardly down-tilting. The study reveals that both the adjacently lying NBTS and BMTS have almost the same spatial growth patterns that are mainly controlled by the movements on their basal thrusts.
{"title":"Active tectonic evolution of two adjoining thrust sheets in the Indo-Myanmar fold-thrust belt, Northeast India","authors":"Alexander S. Kshetrimayum, Pradeep K. Goswami, Chung-Pai Chang, Wu-Lung Chang, Lalit Mohan Joshi","doi":"10.3389/feart.2024.1389308","DOIUrl":"https://doi.org/10.3389/feart.2024.1389308","url":null,"abstract":"The active tectonic aspects of the Indo-Myanmar Range (IMR) have not yet been studied in detail in spite of the fact that it’s seismically active. In the present study qualitative and quantitative geomorphic analyses have been carried out to understand the active tectonic evolution of Nungba, and Barak-Makru thrust sheets (NBTS and BMTS) in the central part of IMR. The focus of the study is on understanding the active spatial growth pattern of adjacent thrust sheets in an evolving mountain range and providing baseline data for further detailed seismotectonic and seismic hazard vulnerability analyses. Drainage characteristics, disposition of landforms and statistical analyses of Normalized Steepness Index (k<jats:sub>sn</jats:sub>), Hypsometric Integral (HI) and Transverse Topography Symmetry Factor (T), computed for a total of 164 4<jats:sup>th</jats:sup>-order drainage basins, reveal that both of these adjoining thrust sheets are actively uplifting. Higher values of k<jats:sub>sn</jats:sub> (mode = 111) and HI (mode = 0.46) in NBTS suggest its faster uplift than the BMTS, which has comparatively lower values of k<jats:sub>sn</jats:sub> (mode = 56) and HI (mode = 0.43). Moreover, the northern parts of the both the thrust sheets are uplifting faster than their southern parts due to along-strike variations in the movement on their basal thrusts, as a result of which the NBTS has been south-southeastwardly down-tilting and the BMTS is south-southwestwardly down-tilting. The study reveals that both the adjacently lying NBTS and BMTS have almost the same spatial growth patterns that are mainly controlled by the movements on their basal thrusts.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-07-01DOI: 10.3389/feart.2024.1426111
Lawrence C. Carter, Ben J. Williamson
Porphyry-type Cu ± Au ± Mo deposits form in the upper (ca. 2–5 km deep) parts of large, long-lived magmatic-hydrothermal systems in which mineralising fluids are thought to be derived from mid-to shallow-crustal magma chambers. Increasingly, however, magmatic systems are viewed as consisting of mush with minor and transient lenses of magma, with mush being a variably packed framework of crystals with interstitial melt and magmatic volatile phase (MVP). In this context, questions remain as to the source (mainly depth) and mechanisms of transport and focussing of the vast volumes of fluids required for shallow level porphyry-type mineralisation. Even more problematic is a paucity of first-order textural evidence for the presence of mush in magmatic-hydrothermal systems, including those which host porphyry-type deposits. To address this, we have studied the aplitic porphyry cupola of the Saginaw Hill magmatic system, Tuscon, Arizona, United States, where magmatic-hydrothermal features are exceptionally well exposed, including a massive silica cap, quartz unidirectional solidification textures (USTs), stockworks of multiple generations of variably mineralised quartz veins and mineralised miarolitic cavities. From field-to micro-scale textural and geochemical studies, particularly observations of vermiform quartz between earlier generations of magmatic quartz and feldspar, we evidence the development of fluid pathways through mush at the magmatic-hydrothermal transition. These are shown to connect and provide fluids and ore constituents to the mineralised miarolitic cavities and early quartz vein stockworks. We suggest that this process should be considered in all new genetic, exploration and numerical models for porphyry and similar types of magmatic-hydrothermal ore-deposits.
{"title":"Migration and focusing of porphyry deposit-forming fluids through aplitic mush of the Saginaw Hill cupola, Arizona, United States","authors":"Lawrence C. Carter, Ben J. Williamson","doi":"10.3389/feart.2024.1426111","DOIUrl":"https://doi.org/10.3389/feart.2024.1426111","url":null,"abstract":"Porphyry-type Cu ± Au ± Mo deposits form in the upper (ca. 2–5 km deep) parts of large, long-lived magmatic-hydrothermal systems in which mineralising fluids are thought to be derived from mid-to shallow-crustal magma chambers. Increasingly, however, magmatic systems are viewed as consisting of mush with minor and transient lenses of magma, with mush being a variably packed framework of crystals with interstitial melt and magmatic volatile phase (MVP). In this context, questions remain as to the source (mainly depth) and mechanisms of transport and focussing of the vast volumes of fluids required for shallow level porphyry-type mineralisation. Even more problematic is a paucity of first-order textural evidence for the presence of mush in magmatic-hydrothermal systems, including those which host porphyry-type deposits. To address this, we have studied the aplitic porphyry cupola of the Saginaw Hill magmatic system, Tuscon, Arizona, United States, where magmatic-hydrothermal features are exceptionally well exposed, including a massive silica cap, quartz unidirectional solidification textures (USTs), stockworks of multiple generations of variably mineralised quartz veins and mineralised miarolitic cavities. From field-to micro-scale textural and geochemical studies, particularly observations of vermiform quartz between earlier generations of magmatic quartz and feldspar, we evidence the development of fluid pathways through mush at the magmatic-hydrothermal transition. These are shown to connect and provide fluids and ore constituents to the mineralised miarolitic cavities and early quartz vein stockworks. We suggest that this process should be considered in all new genetic, exploration and numerical models for porphyry and similar types of magmatic-hydrothermal ore-deposits.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surface waves are widely used in the study of underground structures at various scales because of their dispersion characteristics in layered media. Whether in natural seismology or engineering seismology, surface wave analysis methods have matured and developed for their respective fields. However, in oil and gas exploration, many data processors still tend to consider surface waves as noise that needs to be removed. To make more people pay attention to the application of surface waves and widely utilize surface waves carrying the near surface information in oil and gas exploration, this paper takes the data processing of LH site in Qinghai, China as an example to apply surface wave analysis methods to oil and gas exploration. We first preprocess and perform dispersion imaging method on the seismic record in the LH site to obtain frequency-phase velocity spectrum with good resolution and signal-to-noise ratio. Then, utilizing clustering algorithms, it automatically identifies and picks dispersion curves. Finally, through a simultaneous inversion algorithm of velocity and thickness, it inverts the dispersion curves and obtain S-wave velocity profiles in the depth range of 0–200 m. The near surface is divided into four zones based on velocity ranges and depth ranges. Additionally, we apply the surface waves inversion results as constraints to first-arrival tomography and obtain objectively accurate P-wave velocity profiles and Poisson’s ratio profiles. The results indicate that by applying surface wave analysis methods, the near surface velocity information carried by surface waves can be extracted, providing near surface velocity models for static correction and migration. At the same time, compared with the surface wave application in engineering seismology, the scale of oil and gas exploration is larger, so that the data processing of surface waves is particularly important, otherwise it will affect the picking of the dispersion curve and inversion.
由于面波在层状介质中的弥散特性，面波被广泛应用于各种尺度的地下结构研究中。无论是自然地震学还是工程地震学，面波分析方法在各自的领域中都得到了成熟和发展。然而，在油气勘探领域，许多数据处理人员仍倾向于将面波视为需要去除的噪声。为了让更多的人关注面波的应用，将携带近地表信息的面波广泛应用于油气勘探，本文以中国青海 LH 站点的数据处理为例，将面波分析方法应用于油气勘探。我们首先对LH站点的地震记录进行预处理，并采用频散成像方法获得分辨率和信噪比较好的频相速度谱。然后，利用聚类算法自动识别和挑选频散曲线。最后，通过速度和厚度同步反演算法，对频散曲线进行反演，得到 0-200 米深度范围内的 S 波速度剖面。此外，我们还将面波反演结果作为初至层析成像的约束条件，获得了客观准确的 P 波速度剖面和泊松比剖面。结果表明，通过应用面波分析方法，可以提取面波携带的近地表速度信息，为静力校正和迁移提供近地表速度模型。同时，与工程地震学中的面波应用相比，油气勘探的规模更大，因此面波的数据处理尤为重要，否则会影响频散曲线的选取和反演。
{"title":"Near-surface velocity inversion and modeling method based on surface waves in petroleum exploration: a case study from Qaidam Basin, China","authors":"Xingrong Xu, Yancan Tian, Dunshi Wu, Junfa Xie, Zedan Wang, Tao Zhang","doi":"10.3389/feart.2024.1379668","DOIUrl":"https://doi.org/10.3389/feart.2024.1379668","url":null,"abstract":"Surface waves are widely used in the study of underground structures at various scales because of their dispersion characteristics in layered media. Whether in natural seismology or engineering seismology, surface wave analysis methods have matured and developed for their respective fields. However, in oil and gas exploration, many data processors still tend to consider surface waves as noise that needs to be removed. To make more people pay attention to the application of surface waves and widely utilize surface waves carrying the near surface information in oil and gas exploration, this paper takes the data processing of LH site in Qinghai, China as an example to apply surface wave analysis methods to oil and gas exploration. We first preprocess and perform dispersion imaging method on the seismic record in the LH site to obtain frequency-phase velocity spectrum with good resolution and signal-to-noise ratio. Then, utilizing clustering algorithms, it automatically identifies and picks dispersion curves. Finally, through a simultaneous inversion algorithm of velocity and thickness, it inverts the dispersion curves and obtain S-wave velocity profiles in the depth range of 0–200 m. The near surface is divided into four zones based on velocity ranges and depth ranges. Additionally, we apply the surface waves inversion results as constraints to first-arrival tomography and obtain objectively accurate P-wave velocity profiles and Poisson’s ratio profiles. The results indicate that by applying surface wave analysis methods, the near surface velocity information carried by surface waves can be extracted, providing near surface velocity models for static correction and migration. At the same time, compared with the surface wave application in engineering seismology, the scale of oil and gas exploration is larger, so that the data processing of surface waves is particularly important, otherwise it will affect the picking of the dispersion curve and inversion.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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