Pub Date : 2024-02-14DOI: 10.2113/2023/lithosphere_2023_279
Fangbin Liu, Fan Yang, D. Zheng, Haiyang Ding, Caopeng Li, G. Jepson
Taishan Mountain in the eastern China is a normal-fault-controlled range that formed during the Meso-Cenozoic, in response to large-scale extension and lithospheric thinning of the North China Craton. However, constraints on the timing of the polyphase extensional events which formed the Taishan edifice remain poorly resolved, hindering a detailed understanding of the landscape evolution of this prominent mountain. Here, we conducted apatite (U-Th)/He dating on sixteen samples from three profiles perpendicular in the Taishan Mountain, with a major view to control structures in Taishan Mountain and to resolve the Meso-Cenozoic landscape evolution. The newly determined apatite (U-Th)/He ages show a wide variation range of ~113 to 30 Ma, indicating a slow and protracted cooling history. The inverse thermal history modeling results reveal two pulses of enhanced cooling at ~80 to 60 and 55 to 50 Ma, which we interpret as exhumation related to normal fault activity. Furthermore, one-dimensional modeling indicates that the magnitude of tectonic exhumation is constrained at ≥15 m/Myr across the Yunbuqiao, Zhongtianmen, and Taishan Piedmont faults. Integrating this study and published studies, we suggest that Taishan Mountain underwent four-stage evolution since 100 Ma: (1) the whole Taishan Mountain commenced a continuous and slow exhumation under a weaker tensional environment at ~100 to 80 Ma, (2) the joint growth and interactions within a normal fault system resulted in rapid uplift and promoted the formation of the Proto-Taishan Mountain at ~80 to 60 Ma, (3) the Taishan Mountain underwent exhumation at ~55 to 50 Ma, interpreted as a tectonic response to the Taishan Piedmont Fault, and (4) the last stage (~50 to 0 Ma), the Taishan Mountain experienced protracted exhumation related to normal faulting until now. We attribute the extensive normal faulting to the subduction and slab rollback of the Izanagi-Pacific Plates, which shaped the present-day geomorphology of Taishan Mountain.
{"title":"Apatite (U-Th)/He Thermochronological Constraints on the Landscape Evolution Linked to the Normal Faulting in Taishan Mountain, Eastern China","authors":"Fangbin Liu, Fan Yang, D. Zheng, Haiyang Ding, Caopeng Li, G. Jepson","doi":"10.2113/2023/lithosphere_2023_279","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_279","url":null,"abstract":"\u0000 Taishan Mountain in the eastern China is a normal-fault-controlled range that formed during the Meso-Cenozoic, in response to large-scale extension and lithospheric thinning of the North China Craton. However, constraints on the timing of the polyphase extensional events which formed the Taishan edifice remain poorly resolved, hindering a detailed understanding of the landscape evolution of this prominent mountain. Here, we conducted apatite (U-Th)/He dating on sixteen samples from three profiles perpendicular in the Taishan Mountain, with a major view to control structures in Taishan Mountain and to resolve the Meso-Cenozoic landscape evolution. The newly determined apatite (U-Th)/He ages show a wide variation range of ~113 to 30 Ma, indicating a slow and protracted cooling history. The inverse thermal history modeling results reveal two pulses of enhanced cooling at ~80 to 60 and 55 to 50 Ma, which we interpret as exhumation related to normal fault activity. Furthermore, one-dimensional modeling indicates that the magnitude of tectonic exhumation is constrained at ≥15 m/Myr across the Yunbuqiao, Zhongtianmen, and Taishan Piedmont faults. Integrating this study and published studies, we suggest that Taishan Mountain underwent four-stage evolution since 100 Ma: (1) the whole Taishan Mountain commenced a continuous and slow exhumation under a weaker tensional environment at ~100 to 80 Ma, (2) the joint growth and interactions within a normal fault system resulted in rapid uplift and promoted the formation of the Proto-Taishan Mountain at ~80 to 60 Ma, (3) the Taishan Mountain underwent exhumation at ~55 to 50 Ma, interpreted as a tectonic response to the Taishan Piedmont Fault, and (4) the last stage (~50 to 0 Ma), the Taishan Mountain experienced protracted exhumation related to normal faulting until now. We attribute the extensive normal faulting to the subduction and slab rollback of the Izanagi-Pacific Plates, which shaped the present-day geomorphology of Taishan Mountain.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139964007","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 : 2024-01-25DOI: 10.2113/2023/lithosphere_2023_259
Yuxiong Ma, Zhao Yang, Dengfeng He, Xiaohui Shi, Bo Zhou, Jiali You, Dali Ju, Yunpeng Dong
The East Kunlun Orogenic Belt (E-KOB) stands out as one of the most prominent basin-mountain geomorphic features in the northern interior of the Tibetan Plateau. It records a series of accretion-collision events from the Mesozoic to the Cenozoic. In particular, with the uplifting of the Tibetan Plateau, the E-KOB experienced intracontinental deformation and exhumation in the Cenozoic. Clarifying the exhumation history of the E-KOB is crucial to define the growth time and mechanism of the Tibetan Plateau. In this study, we apply detrital zircon fission-track (ZFT) and apatite fission-track (AFT) analyses on modern river sands in order to constrain the regional exhumation history of the eastern E-KOB. Four peak ages have been identified and interpreted as results of rapid exhumation correlated with intracontinental deformation. Two older peak ages at 144.7–141.0 and 114.6–82.1 Ma are in good accordance with the collision time of the north-south Lhasa-Qiangtang Block along the Bangong-Nujiang suture zone and the subsequent progressive deformation stage toward the north. Peak age at 60.9–45.3 Ma is coeval with the initial timing of the India-Asia collision. The youngest peak age at 25.1–18.3 Ma matches well with the extensive outward and upward growth of the Tibetan Plateau during the Oligocene to Miocene time. The Cretaceous and early Cenozoic rapid exhumations suggest that the E-KOB has been involved in the intracontinental deformation induced by collisions of the Lhasa-Qiangtang and India-Asia from the south. It implies that the northern Tibetan Plateau likely has been elevated or was a structural high before the Eocene. In addition, some of our detrital samples show a younger ZFT peak age than the AFT peak age. We attributed this data bias to the contribution of hydrodynamic sorting and/or lithological difference. The combination of ZFT and AFT dating has advantages in eliminating interfering age signals in detrital thermochronology.
{"title":"Polyphase Exhumation of the East Kunlun Orogenic Belt: Evidence from Modern River Detrital Zircon and Apatite Fission Track Dating","authors":"Yuxiong Ma, Zhao Yang, Dengfeng He, Xiaohui Shi, Bo Zhou, Jiali You, Dali Ju, Yunpeng Dong","doi":"10.2113/2023/lithosphere_2023_259","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_259","url":null,"abstract":"\u0000 The East Kunlun Orogenic Belt (E-KOB) stands out as one of the most prominent basin-mountain geomorphic features in the northern interior of the Tibetan Plateau. It records a series of accretion-collision events from the Mesozoic to the Cenozoic. In particular, with the uplifting of the Tibetan Plateau, the E-KOB experienced intracontinental deformation and exhumation in the Cenozoic. Clarifying the exhumation history of the E-KOB is crucial to define the growth time and mechanism of the Tibetan Plateau. In this study, we apply detrital zircon fission-track (ZFT) and apatite fission-track (AFT) analyses on modern river sands in order to constrain the regional exhumation history of the eastern E-KOB. Four peak ages have been identified and interpreted as results of rapid exhumation correlated with intracontinental deformation. Two older peak ages at 144.7–141.0 and 114.6–82.1 Ma are in good accordance with the collision time of the north-south Lhasa-Qiangtang Block along the Bangong-Nujiang suture zone and the subsequent progressive deformation stage toward the north. Peak age at 60.9–45.3 Ma is coeval with the initial timing of the India-Asia collision. The youngest peak age at 25.1–18.3 Ma matches well with the extensive outward and upward growth of the Tibetan Plateau during the Oligocene to Miocene time. The Cretaceous and early Cenozoic rapid exhumations suggest that the E-KOB has been involved in the intracontinental deformation induced by collisions of the Lhasa-Qiangtang and India-Asia from the south. It implies that the northern Tibetan Plateau likely has been elevated or was a structural high before the Eocene. In addition, some of our detrital samples show a younger ZFT peak age than the AFT peak age. We attributed this data bias to the contribution of hydrodynamic sorting and/or lithological difference. The combination of ZFT and AFT dating has advantages in eliminating interfering age signals in detrital thermochronology.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139595831","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}
The Beishan orogen, a significant component of the southern Altaids, presents an opportunity for investigating the intracontinental deformation and exhumation history of the Altaids during the Mesozoic era. Although previous studies indicated that the Beishan orogen has experienced multiple reactivation since the late Mesozoic, the precise extent of these events remains poorly constrained. Here, we provide a comprehensive synthesis of field observations and apatite fission track (AFT) thermochronological dating throughout the Beishan orogen. Detailed field observations confirmed four major E-W trending thrusts in our study area. Based on the youngest truncated strata associated with the thrusts and previous dating results from neighboring regions, we propose that these thrust sheets likely developed in the late Middle Jurassic. AFT dating results from seven pre-Mesozoic granitoid samples and associated with thermal history modeling demonstrate that the Beishan orogen experienced a rapid basement cooling during the mid-Cretaceous (~115–80 Ma). Moreover, a compilation of previously published and newly gained AFT data reveals a comparable mid-Cretaceous cooling event in other parts of Central Asia, such as Qilian Shan, Eastern Tianshan, and Altai-Sayan. This observation suggests that the mid-Cretaceous cooling event is more likely to be regional rather than localized. This mid-Cretaceous cooling pulse is interpreted as a tectonic exhumation controlled by boundary faults and related to the rotation of the Junggar and Tarim basins. These processes are linked to distant plate-margin events along the Eurasian continent.
{"title":"Mid-Cretaceous Accelerated Cooling of the Beishan Orogen, NW China: Evidence from Apatite Fission Track Thermochronology","authors":"Fujun Wang, Meng Luo, Zhiyuan He, Yiqiong Wang, Bihai Zheng, Zhiyong Zhang, Xiao Hu, Wenbin Zhu","doi":"10.2113/2023/lithosphere_2023_239","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_239","url":null,"abstract":"\u0000 The Beishan orogen, a significant component of the southern Altaids, presents an opportunity for investigating the intracontinental deformation and exhumation history of the Altaids during the Mesozoic era. Although previous studies indicated that the Beishan orogen has experienced multiple reactivation since the late Mesozoic, the precise extent of these events remains poorly constrained. Here, we provide a comprehensive synthesis of field observations and apatite fission track (AFT) thermochronological dating throughout the Beishan orogen. Detailed field observations confirmed four major E-W trending thrusts in our study area. Based on the youngest truncated strata associated with the thrusts and previous dating results from neighboring regions, we propose that these thrust sheets likely developed in the late Middle Jurassic. AFT dating results from seven pre-Mesozoic granitoid samples and associated with thermal history modeling demonstrate that the Beishan orogen experienced a rapid basement cooling during the mid-Cretaceous (~115–80 Ma). Moreover, a compilation of previously published and newly gained AFT data reveals a comparable mid-Cretaceous cooling event in other parts of Central Asia, such as Qilian Shan, Eastern Tianshan, and Altai-Sayan. This observation suggests that the mid-Cretaceous cooling event is more likely to be regional rather than localized. This mid-Cretaceous cooling pulse is interpreted as a tectonic exhumation controlled by boundary faults and related to the rotation of the Junggar and Tarim basins. These processes are linked to distant plate-margin events along the Eurasian continent.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139595962","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}
The Proto-Tethys Ocean has played a significant role in the geological history of Earth. However, ongoing debates persist regarding the timing and polarity of its early subduction. Volcanic rocks associated with iron deposits in the Bulunkuole Complex, West Kunlun Orogen, offer insights into both the complex’s formation age and Proto-Tethys evolution. This study presents newly obtained zircon U–Pb age data (~536 Ma) along with comprehensive whole-rock major and trace element and Sr–Nd–Hf isotope analyses of these volcanic rocks. Our dataset implies that the Bulunkuole Complex partly formed in the early Paleozoic rather than entirely in the Paleoproterozoic, as previously suggested. Geochemically, the volcanic rocks exhibit enrichments in large ion lithophile elements and light rare earth elements, along with depletions in high-field strength elements. They also display elevated initial 87Sr/86Sr values (0.71093, 0.72025) and negative εNd(t) values (−5.13, −6.18), classifying them as continental arc volcanic rocks. These geochemical fingerprints, complemented by zircon εHf(t) values (−12.7 to −1.6), indicate that the parental magmas of the volcanic rocks were produced by partial melting of the lithospheric mantle wedge, which had been metasomatized by subducted sediment-derived melts. The available data, in conjunction with previously published findings, strongly suggest that the Proto-Tethys Ocean subducted southward prior to approximately 536 Ma due to the assembly of Gondwana. Subsequent slab rollback may have resulted in a crustal thinning of 9–25 km during 536–514 Ma. Further shifts in subduction dynamics led to the transition from high-angle subduction to either normal or low-angle subduction, facilitating the formation of a thicker crust ranging from 39 to 70 km between 514 and 448 Ma. This study, therefore, provides valuable insights into the early evolution of the Proto-Tethys Ocean and contributes significantly to our understanding of the tectonic history of the West Kunlun Orogen.
原特提斯洋在地球地质历史上发挥了重要作用。然而，关于其早期俯冲的时间和极性的争论一直存在。西昆仑造山带布伦郭勒复合体中与铁矿床相关的火山岩为了解该复合体的形成年代和原特提斯演化提供了线索。本研究提供了新获得的锆石U-Pb年龄数据（约536 Ma），以及对这些火山岩进行的全面的全岩主要元素、微量元素和Sr-Nd-Hf同位素分析。我们的数据集表明，布伦郭勒复合体部分形成于早古生代，而不是像以前认为的那样完全形成于古近代。从地球化学角度看，火山岩富含大离子亲岩元素和轻稀土元素，同时贫乏高场强元素。它们还显示出较高的 87Sr/86Sr 初始值（0.71093，0.72025）和负的 εNd(t)值（-5.13，-6.18），可将其归类为大陆弧火山岩。这些地球化学特征以及锆石的εHf(t)值（-12.7 至-1.6）表明，火山岩的母岩浆是由岩石圈地幔楔部分熔化产生的，而岩石圈地幔楔是由俯冲沉积物衍生的熔体变质而成的。现有数据以及之前公布的研究结果有力地表明，由于冈瓦纳的形成，原特提斯洋在大约 536 Ma 之前向南俯冲。随后的板块回滚可能导致地壳在 536-514 Ma 期间变薄了 9-25 km。俯冲动力学的进一步转变导致了从高角度俯冲向正常或低角度俯冲的过渡，促进了在 514 至 448 Ma 期间形成 39 至 70 km 厚的地壳。因此，这项研究为了解原特提斯洋的早期演化提供了宝贵的见解，并大大有助于我们了解西昆仑造山带的构造历史。
{"title":"New Insights on the Early Proto-Tethys Subduction History: Evidence from Ages and Petrogenesis of Volcanic Rocks in the Bulunkuole Complex, West Kunlun Orogen","authors":"Zhenju Zhou, Yanjing Chen, H. Tang, Yanshuang Wu, Qiugen Li, Zhengle Chen","doi":"10.2113/2024/lithosphere_2023_290","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_290","url":null,"abstract":"\u0000 The Proto-Tethys Ocean has played a significant role in the geological history of Earth. However, ongoing debates persist regarding the timing and polarity of its early subduction. Volcanic rocks associated with iron deposits in the Bulunkuole Complex, West Kunlun Orogen, offer insights into both the complex’s formation age and Proto-Tethys evolution. This study presents newly obtained zircon U–Pb age data (~536 Ma) along with comprehensive whole-rock major and trace element and Sr–Nd–Hf isotope analyses of these volcanic rocks. Our dataset implies that the Bulunkuole Complex partly formed in the early Paleozoic rather than entirely in the Paleoproterozoic, as previously suggested. Geochemically, the volcanic rocks exhibit enrichments in large ion lithophile elements and light rare earth elements, along with depletions in high-field strength elements. They also display elevated initial 87Sr/86Sr values (0.71093, 0.72025) and negative εNd(t) values (−5.13, −6.18), classifying them as continental arc volcanic rocks. These geochemical fingerprints, complemented by zircon εHf(t) values (−12.7 to −1.6), indicate that the parental magmas of the volcanic rocks were produced by partial melting of the lithospheric mantle wedge, which had been metasomatized by subducted sediment-derived melts. The available data, in conjunction with previously published findings, strongly suggest that the Proto-Tethys Ocean subducted southward prior to approximately 536 Ma due to the assembly of Gondwana. Subsequent slab rollback may have resulted in a crustal thinning of 9–25 km during 536–514 Ma. Further shifts in subduction dynamics led to the transition from high-angle subduction to either normal or low-angle subduction, facilitating the formation of a thicker crust ranging from 39 to 70 km between 514 and 448 Ma. This study, therefore, provides valuable insights into the early evolution of the Proto-Tethys Ocean and contributes significantly to our understanding of the tectonic history of the West Kunlun Orogen.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139607050","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":null,"pages":null},"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_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":null,"pages":null},"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_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":null,"pages":null},"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
{"title":"Late Cenozoic Cooling History of the Xigaze Fore-Arc Basin along the Yarlung–Zangbo Suture Zone (Southern Tibet): New Insights from Low-Temperature Thermochronology","authors":"Shida Song, Zhiyuan He, Wenbo Su, Linglin Zhong, Kanghui Zhong, Stijn Glorie, Yifan Song, Johan De Grave","doi":"10.2113/2024/lithosphere_2023_211","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_211","url":null,"abstract":"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 ","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139463005","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":null,"pages":null},"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_219
Li Danli, Dai Bing, Zhang Lei
Appropriate simulation set parameters are the precondition to obtain accurate results; while the simulation results are affected by multiple factors, it is thus crucial to investigate the sensibility of different factors. This paper first analyses the application situation of numerical simulation software in the field of geotechnical engineering and finds that Fast Lagrangian analysis of continua in three dimensions (FLAC3D) has been widely used on roadways or tunnels. Then, taking the roadway excavation process as the engineering background, FLAC3D was used to create 171 schemes of different simulation parameters and analyze the influence of different factors on the simulation results. The findings show that there is a considerable difference in the degree of effect of different parameters on the simulation results. Most of the factors have a remarkable effect on the numerical simulation results (displacement and stress), and only some factors (parameter uniformity and density) have almost no effect on the results. Meanwhile, the trend of displacement and stress is opposite in most cases. In addition, some neglected factors can also have a considerable effect on the simulation results, such as the zone amount; therefore, it is necessary to avoid the variation of nonstudy factors as possible when carrying out the numerical simulation. This study may significantly assist concerned engineers and technicians in developing a more organized and thorough grasp of the impacts of various parameters on simulation outcomes.The challenges of mining underground mineral resources have grown increasingly difficult and dangerous due to the increasing depth of mining. Numerous researchers have conducted studies to address these challenges that limit the safe and effective production of mines, from the appearance [1, 2] to the essence [3, 4], from the Macro [5, 6] to the Microscopic [7, 8] to the Micro [9, 10] structures, and from the single physical field [11, 12] to multiple physical coupling field [13, 14], and there have been many outcomes. Nevertheless, the complex and variable environment of underground roadways makes it difficult for traditional theoretical analyses [15, 16] to resolve a specific complex engineering problem, and it is laborious and time-consuming to conduct scaled physical simulation tests [17, 18], and it is difficult to reproduce overly complex scenarios, and the accuracy of the obtained results cannot be guaranteed. As the understanding of the properties of geotechnical materials grows and computers continue to develop, computational mechanics [19] is in a flourishing stage. Considering the mutual coupling relationship between various fields, computational mechanics, an emerging interdisciplinary discipline, has significant advantages in processing practice engineering problems. Numerical simulation code based on computational mechanics can simulate approximate object comprehensions for almost any complex operating conditions. At presen
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