2024 Vol. 49, No. 12
Display Method:
2024, 49(12): 4265-4277.
doi: 10.3799/dqkx.2024.059
PDF 8192KB
Abstract:
Xingfengshan is a representative gold-tungsten deposit in the Xiangzhong metallogenic belt. The age of gold mineralization, the source of ore-forming metals and the genesis of the deposit are still controversial. Based on detailed petrographic observation and LA-(MC)-ICP-MS analysis, in situ U-Pb dating of hydrothermal apatite and in situ S-isotope analysis of arsenopyrite in the auriferous quartz veins are carried out in this paper to constrain the age of gold mineralization, trace the source of ore-forming metals, and deepen the understanding of the genesis of the deposit. The U-Pb age of hydrothermal apatite in gold-bearing quartz veins is 215.1±7.5 Ma, which is consistent with the intrusion age of the Baimashan complex. The δ34S values of arsenopyrite are centrally distributed between -9.2‰ to -7.7‰, indicating that the ore-forming metal is derived from a mixture of magmatic-hydrothermal fluids and host rocks.. The study shows that the W mineralization and Au mineralization of the Xingfengshan deposit occurred in the Late Triassic, and both may be the products of magmatic activities of the Baimashan igneous complex, and the Xingfengshan deposit should belong to the intrusion-related gold deposit.
Xingfengshan is a representative gold-tungsten deposit in the Xiangzhong metallogenic belt. The age of gold mineralization, the source of ore-forming metals and the genesis of the deposit are still controversial. Based on detailed petrographic observation and LA-(MC)-ICP-MS analysis, in situ U-Pb dating of hydrothermal apatite and in situ S-isotope analysis of arsenopyrite in the auriferous quartz veins are carried out in this paper to constrain the age of gold mineralization, trace the source of ore-forming metals, and deepen the understanding of the genesis of the deposit. The U-Pb age of hydrothermal apatite in gold-bearing quartz veins is 215.1±7.5 Ma, which is consistent with the intrusion age of the Baimashan complex. The δ34S values of arsenopyrite are centrally distributed between -9.2‰ to -7.7‰, indicating that the ore-forming metal is derived from a mixture of magmatic-hydrothermal fluids and host rocks.. The study shows that the W mineralization and Au mineralization of the Xingfengshan deposit occurred in the Late Triassic, and both may be the products of magmatic activities of the Baimashan igneous complex, and the Xingfengshan deposit should belong to the intrusion-related gold deposit.
2024, 49(12): 4278-4302.
doi: 10.3799/dqkx.2024.024
Abstract:
The East Kunlun orogenic belt is located in the northeast of the Qinghai-Tibet Plateau. It experienced the early tectonic evolution of the Proto-Tethys Ocean and formed a series of marine sedimentary manganese deposits . However, there are still different understandings on the specific details of the evolution of the Proto-Tethys Ocean in East Kunlun, such as expansion and subduction, active and passive continental margins, island arc and back-arc basin. There are also controversies regarding the timing of ocean closure during the Middle-Late Ordovician or Early Silurian periods. Based on the geological and geochemical research of sandstone and siliceous rock in marine sedimentary manganese deposits in East Kunlun, it was indicated that Hongshuihe ferromanganese and Langmuri manganese deposits formed in the Mesoproterozoic, as well as Ordovician-Early Silurian Santonggou north manganese deposit, show geochemical characteristics of active continental margin, but Santonggou Ⅵ-Ⅶ manganese ore belt formed in the Neoproterozoic shows the tectonic attribute of passive continental margins. Comprehensive research indicates that the minddle and south Kunlun belts in Proto-Tethys tectonic domain has undergone an evolution processes from Mesoproterozoic active continental margin to Neoproterozoic passive continental margin, and Ordovician-Early Silurian Nachitai Group was formed in the stage of island arc accretion or back-arc basin in the Proto-Tethys Ocean.
The East Kunlun orogenic belt is located in the northeast of the Qinghai-Tibet Plateau. It experienced the early tectonic evolution of the Proto-Tethys Ocean and formed a series of marine sedimentary manganese deposits . However, there are still different understandings on the specific details of the evolution of the Proto-Tethys Ocean in East Kunlun, such as expansion and subduction, active and passive continental margins, island arc and back-arc basin. There are also controversies regarding the timing of ocean closure during the Middle-Late Ordovician or Early Silurian periods. Based on the geological and geochemical research of sandstone and siliceous rock in marine sedimentary manganese deposits in East Kunlun, it was indicated that Hongshuihe ferromanganese and Langmuri manganese deposits formed in the Mesoproterozoic, as well as Ordovician-Early Silurian Santonggou north manganese deposit, show geochemical characteristics of active continental margin, but Santonggou Ⅵ-Ⅶ manganese ore belt formed in the Neoproterozoic shows the tectonic attribute of passive continental margins. Comprehensive research indicates that the minddle and south Kunlun belts in Proto-Tethys tectonic domain has undergone an evolution processes from Mesoproterozoic active continental margin to Neoproterozoic passive continental margin, and Ordovician-Early Silurian Nachitai Group was formed in the stage of island arc accretion or back-arc basin in the Proto-Tethys Ocean.
2024, 49(12): 4303-4317.
doi: 10.3799/dqkx.2023.173
Abstract:
In order to study whether chlorite trace elements can effectively classify different genetic deposit types, in this paper, 2 928 trace element data of chlorite from 13 different deposits were collected, which belong to three distinct genetic types, including porphyry, skarn and epithermal deposits.Three different machine learning algorithms, including random forest, support vector machine (SVM) and artificial neural network, were used to establish classification models for the genetic types of deposits and analyze the importance of characteristics.The results show that the SVM model based on Ni, Cr, Co, Sr, V and Zn, 6 trace elements have the best classification effect, the highest Kappa coefficient is 0.89, the weighted average score of precision, recall and F1 value reach 0.96, and Ni, V and Co are the three most critical discriminant elements. In this paper it fully confirms that the machine learning classification model based on chlorite mineral trace elements can discriminate deposit types and provide an important indicator for the rapid evaluation of regional scale prospecting.
In order to study whether chlorite trace elements can effectively classify different genetic deposit types, in this paper, 2 928 trace element data of chlorite from 13 different deposits were collected, which belong to three distinct genetic types, including porphyry, skarn and epithermal deposits.Three different machine learning algorithms, including random forest, support vector machine (SVM) and artificial neural network, were used to establish classification models for the genetic types of deposits and analyze the importance of characteristics.The results show that the SVM model based on Ni, Cr, Co, Sr, V and Zn, 6 trace elements have the best classification effect, the highest Kappa coefficient is 0.89, the weighted average score of precision, recall and F1 value reach 0.96, and Ni, V and Co are the three most critical discriminant elements. In this paper it fully confirms that the machine learning classification model based on chlorite mineral trace elements can discriminate deposit types and provide an important indicator for the rapid evaluation of regional scale prospecting.
2024, 49(12): 4318-4334.
doi: 10.3799/dqkx.2024.054
Abstract:
Three main types of ore bdies are well developed in the Weilasituo deposit, including alkaline granite type Sn-Rb ore body, cryptoexplosive breccia-type Li-Rb ore body, and quartz vein type Sn ore body. The cryptoexplosive breccia-type ore body was located between the other two types of ore bodies and was assumed as the key point to understand the process and genesis of the cryptoexplosive breccia-type ore body. This contribution mainly focuses on quartz crystals and fluid inclusions therein from the cryptoexplosive breccia-type ore body. Through quartz cathodoluminescence imaging, fluid inclusion microthermometry, laser Raman spectroscopy, and in situ oxygen isotope analysis, it tries to address the relationship between fluid evolution and Li-Rb mineralization. Three stages (Q1, Q2, and Q3) of crystallization have been identified based on quartz CL imaging, while Q1 and Q2 are well-developed and closely related to Li-Rb mineralization. Fluid inclusions in Q2 exhibit similar salinity but lower homogeneous temperatures than those in Q1.The oxygen isotope composition of Q2 is lighter than that of Q1. Combined with previous and our study results, it is assumed that the cryptoexplosive breccia-type mineralization of Weilasituo should be formed by cryptoexplosion of volatile which converges on the top of mineralized porphyry, and the mixing of magmatic-hydrothermal fluid and meteoric water might control the precipitation process of zinnwaldite, and eventually form the cryptoexplosive breccia-type Li-Rb mineralization of Weilasituo.
Three main types of ore bdies are well developed in the Weilasituo deposit, including alkaline granite type Sn-Rb ore body, cryptoexplosive breccia-type Li-Rb ore body, and quartz vein type Sn ore body. The cryptoexplosive breccia-type ore body was located between the other two types of ore bodies and was assumed as the key point to understand the process and genesis of the cryptoexplosive breccia-type ore body. This contribution mainly focuses on quartz crystals and fluid inclusions therein from the cryptoexplosive breccia-type ore body. Through quartz cathodoluminescence imaging, fluid inclusion microthermometry, laser Raman spectroscopy, and in situ oxygen isotope analysis, it tries to address the relationship between fluid evolution and Li-Rb mineralization. Three stages (Q1, Q2, and Q3) of crystallization have been identified based on quartz CL imaging, while Q1 and Q2 are well-developed and closely related to Li-Rb mineralization. Fluid inclusions in Q2 exhibit similar salinity but lower homogeneous temperatures than those in Q1.The oxygen isotope composition of Q2 is lighter than that of Q1. Combined with previous and our study results, it is assumed that the cryptoexplosive breccia-type mineralization of Weilasituo should be formed by cryptoexplosion of volatile which converges on the top of mineralized porphyry, and the mixing of magmatic-hydrothermal fluid and meteoric water might control the precipitation process of zinnwaldite, and eventually form the cryptoexplosive breccia-type Li-Rb mineralization of Weilasituo.
2024, 49(12): 4335-4350.
doi: 10.3799/dqkx.2023.191
Abstract:
Danchi metallogenic belt is one of the most important nonferrous metal industry bases. It is to be the research focus owing to the large scale of Sn and Sb metal budget. The genesis of Sn-polymetallic mineralization during the Late Cretaceous and the relationship between Zn-Sn and Sb mineralization in the belt remain unclear. The Bawang deposit, a recently discovered paleokarst infilled type deposit, occurs in the west limb of the Wuxu anticline. Basing on the earlier study of structural analysis, mineralogy, and cassiterite U-Pb ages, in this study it presents element mapping of ores by micro-XRF (μ-XRF) analysis, and in situ U-Pb laser ablation-magnetic sectorfield-inductively coupled plasma mass spectrometer (LA-SF-ICP-MS) ages of calcite during the antimony mineralization stage. Micro-XRF analysis revealed that the sphalerite, cassiterite-quartz, and arsenopyrite mineralization have taken place in order in the Bawang deposit. Calcite U-Pb dating provides a lower intercept ages of 62.8±1.1 Ma (MSWD = 2.6; 2σ). Combined with previous ages of Zn-Sn mineralization, mineralogy, and μ-XRF analysis, the Zn-Sn mineralization is 30 Ma earlier than Sb mineralization. The pressure contrast existed between the fluid pressure at the site of ore deposition and the fluid pressure within the concealed intrusion is the key dynamics of fluid flow for the tin mineralization.
Danchi metallogenic belt is one of the most important nonferrous metal industry bases. It is to be the research focus owing to the large scale of Sn and Sb metal budget. The genesis of Sn-polymetallic mineralization during the Late Cretaceous and the relationship between Zn-Sn and Sb mineralization in the belt remain unclear. The Bawang deposit, a recently discovered paleokarst infilled type deposit, occurs in the west limb of the Wuxu anticline. Basing on the earlier study of structural analysis, mineralogy, and cassiterite U-Pb ages, in this study it presents element mapping of ores by micro-XRF (μ-XRF) analysis, and in situ U-Pb laser ablation-magnetic sectorfield-inductively coupled plasma mass spectrometer (LA-SF-ICP-MS) ages of calcite during the antimony mineralization stage. Micro-XRF analysis revealed that the sphalerite, cassiterite-quartz, and arsenopyrite mineralization have taken place in order in the Bawang deposit. Calcite U-Pb dating provides a lower intercept ages of 62.8±1.1 Ma (MSWD = 2.6; 2σ). Combined with previous ages of Zn-Sn mineralization, mineralogy, and μ-XRF analysis, the Zn-Sn mineralization is 30 Ma earlier than Sb mineralization. The pressure contrast existed between the fluid pressure at the site of ore deposition and the fluid pressure within the concealed intrusion is the key dynamics of fluid flow for the tin mineralization.
2024, 49(12): 4351-4368.
doi: 10.3799/dqkx.2023.180
Abstract:
The Haidewula uranium deposit is located in the South Kunlun Belt of the East Kunlun orogenic belt and represents the first independent volcanic-related uranium deposit in the Qinghai-Tibet plateau of China. While previous studies have examined the mineralization characteristics of the deposits, there has been preliminarily studied by predecessors, but the ore-forming fluid and gangue minerals of the deposit have been poorly limited research on the ore-forming fluids and gangue minerals. Hematite, which is commonly found in various uranium deposits, is closely associated with uranium mineralization. This research focuses on studying the petrographic and mineral chemical characteristics of hematite in the Haidewula uranium deposit to investigate its implications for the source and nature of the ore-forming fluid. The aim is to provide a theoretical foundation for understanding the genesis of the Haidewula deposit and guide future prospecting and exploration efforts. The findings reveal that fissure-filled hematite in the early stage of mineralization is formed through alkali alteration and cavitation effect. The mineralization clumpy hematite in the metallogenic period is a result of the reaction between strongly oxidized metallogenic hydrothermal fluids and Fe2+ in pyrite and surrounding rock. This reaction restricts the oxidation of the mineralizing environment, reduces the oxidation of the mineralizing fluid, and leads to the precipitation of pitchblende. The ore-forming fluid during the formation of hematite in the Haidewula uranium deposit exhibits characteristics of a mixing of meteoric water and mantle-derived fluid. The mantle-derived fluid may have a connection with Triassic diabase magmatic activity. The fluid during the hematite formation is a high oxygen fugacity Cl- rich fluid, which gradually changes from a Cl- rich acidic fluid to an alkaline fluid through reactions with the surrounding rock. The simultaneous enrichment of U-Mo-W in Haidewula hematite suggests that the ore-forming materials in the deposit may primarily originate from the host felsic volcanic rock.
The Haidewula uranium deposit is located in the South Kunlun Belt of the East Kunlun orogenic belt and represents the first independent volcanic-related uranium deposit in the Qinghai-Tibet plateau of China. While previous studies have examined the mineralization characteristics of the deposits, there has been preliminarily studied by predecessors, but the ore-forming fluid and gangue minerals of the deposit have been poorly limited research on the ore-forming fluids and gangue minerals. Hematite, which is commonly found in various uranium deposits, is closely associated with uranium mineralization. This research focuses on studying the petrographic and mineral chemical characteristics of hematite in the Haidewula uranium deposit to investigate its implications for the source and nature of the ore-forming fluid. The aim is to provide a theoretical foundation for understanding the genesis of the Haidewula deposit and guide future prospecting and exploration efforts. The findings reveal that fissure-filled hematite in the early stage of mineralization is formed through alkali alteration and cavitation effect. The mineralization clumpy hematite in the metallogenic period is a result of the reaction between strongly oxidized metallogenic hydrothermal fluids and Fe2+ in pyrite and surrounding rock. This reaction restricts the oxidation of the mineralizing environment, reduces the oxidation of the mineralizing fluid, and leads to the precipitation of pitchblende. The ore-forming fluid during the formation of hematite in the Haidewula uranium deposit exhibits characteristics of a mixing of meteoric water and mantle-derived fluid. The mantle-derived fluid may have a connection with Triassic diabase magmatic activity. The fluid during the hematite formation is a high oxygen fugacity Cl- rich fluid, which gradually changes from a Cl- rich acidic fluid to an alkaline fluid through reactions with the surrounding rock. The simultaneous enrichment of U-Mo-W in Haidewula hematite suggests that the ore-forming materials in the deposit may primarily originate from the host felsic volcanic rock.
2024, 49(12): 4369-4384.
doi: 10.3799/dqkx.2024.105
Abstract:
In this paper, systematic analysis of the Yujingshan monzogranite is conducted to investigate its petrogenesis and source. The results show that the crystallization age of the monzogranite is 125 ± 1 Ma. The εHf (t) values of zircons are between -6.5 and -2.0 and the two-stage model ages (tDM2(Hf)) are 1.6-1.3 Ga, which suggests that the magma was derived by partial melting of Mesoproterozoic crust. Geochemically, the Yujingshan pluton belongs to peraluminous and high K calc-alkaline series with A/CNK=1.10-1.15 and K2O/Na2O=1.01-1.45. The ΣREE of the Yujingshan pluton is relatively low (ΣREE=48.54×10-6~80.32×10-6). LREE and HREE fractionation is not significant ((La/Yb)N=2.91-4.32), but there is a negative Eu anomaly (σEu=0.19-0.28). The samples are enriched with large ion lithophilic elements (Rb, Sr, Th, U, K) and depleted in high field strength elements (Nb and Ti). The enriched Sm-Nd isotopic composition [εNd(t=125) of -10.1 to -8.9] indicates that the magma originated from remelting of ancient crustal materials. Comprehensive analysis shows that the Yujingshan monzogranite was generated by the partial melting of Mesoproterozoic argillaceous rocks and experienced fractional crystallization. The magma belongs to highly differentiated S-type granites, which formed in a tectonic regime transformation process going from compression to extension during the northwest subduction of the paleo-Pacific plate. Subsequently, ductile shearing occurred during the Late Cretaceous, resulting in mylonitization of the Yujingshan pluton. This research, combined with regional magmatic and structural geology data, suggests that the tectonic regime transformation in the South China block occurred at Late Mesozoic, and that regional extension continued until the late Early Cretaceous.
In this paper, systematic analysis of the Yujingshan monzogranite is conducted to investigate its petrogenesis and source. The results show that the crystallization age of the monzogranite is 125 ± 1 Ma. The εHf (t) values of zircons are between -6.5 and -2.0 and the two-stage model ages (tDM2(Hf)) are 1.6-1.3 Ga, which suggests that the magma was derived by partial melting of Mesoproterozoic crust. Geochemically, the Yujingshan pluton belongs to peraluminous and high K calc-alkaline series with A/CNK=1.10-1.15 and K2O/Na2O=1.01-1.45. The ΣREE of the Yujingshan pluton is relatively low (ΣREE=48.54×10-6~80.32×10-6). LREE and HREE fractionation is not significant ((La/Yb)N=2.91-4.32), but there is a negative Eu anomaly (σEu=0.19-0.28). The samples are enriched with large ion lithophilic elements (Rb, Sr, Th, U, K) and depleted in high field strength elements (Nb and Ti). The enriched Sm-Nd isotopic composition [εNd(t=125) of -10.1 to -8.9] indicates that the magma originated from remelting of ancient crustal materials. Comprehensive analysis shows that the Yujingshan monzogranite was generated by the partial melting of Mesoproterozoic argillaceous rocks and experienced fractional crystallization. The magma belongs to highly differentiated S-type granites, which formed in a tectonic regime transformation process going from compression to extension during the northwest subduction of the paleo-Pacific plate. Subsequently, ductile shearing occurred during the Late Cretaceous, resulting in mylonitization of the Yujingshan pluton. This research, combined with regional magmatic and structural geology data, suggests that the tectonic regime transformation in the South China block occurred at Late Mesozoic, and that regional extension continued until the late Early Cretaceous.
2024, 49(12): 4385-4403.
doi: 10.3799/dqkx.2023.164
Abstract:
Zaozigou is a representative gold deposit in West Qinling orogenic belt. The source of ore-forming materials and the genetic type of the deposit are still in debate. The microstructure, trace elements and sulfur isotopes of gold-bearing pyrite were analyzed by LA-ICP-MS to constrain the source of ore-forming materials and ore genesis. Pyrite can be divided into at least three generations (Py1, Py2 and Py3), of which Py2 and Py3 are the main gold-bearing minerals. Py1 is characterized by high Pb and low Ag, Au, W, and Tl contents. The δ34S values of Py1 range from -7.4‰ to -5.8‰. The Au, As, Ag, and W contents of Py2 are relatively high, while the Tl content is relatively low. The δ34S values of Py2 range from -16.6‰ to -4.2 ‰, and Au mainly exists in the form of solid solution (Au+). Py3 has high contents of Sb and Tl, and low contents of W and Bi. The δ34S values of Py3 vary from -25.2‰ to -20.1‰. The gold occurs as structurally bound gold and nanoparticles. The study indicates that the precipitation and enrichment of gold in the Zaozigou gold deposit may be related to water-rock interactions and fluid boiling. The Zaozigou gold deposit should be classified as an orogenic type gold deposit.
Zaozigou is a representative gold deposit in West Qinling orogenic belt. The source of ore-forming materials and the genetic type of the deposit are still in debate. The microstructure, trace elements and sulfur isotopes of gold-bearing pyrite were analyzed by LA-ICP-MS to constrain the source of ore-forming materials and ore genesis. Pyrite can be divided into at least three generations (Py1, Py2 and Py3), of which Py2 and Py3 are the main gold-bearing minerals. Py1 is characterized by high Pb and low Ag, Au, W, and Tl contents. The δ34S values of Py1 range from -7.4‰ to -5.8‰. The Au, As, Ag, and W contents of Py2 are relatively high, while the Tl content is relatively low. The δ34S values of Py2 range from -16.6‰ to -4.2 ‰, and Au mainly exists in the form of solid solution (Au+). Py3 has high contents of Sb and Tl, and low contents of W and Bi. The δ34S values of Py3 vary from -25.2‰ to -20.1‰. The gold occurs as structurally bound gold and nanoparticles. The study indicates that the precipitation and enrichment of gold in the Zaozigou gold deposit may be related to water-rock interactions and fluid boiling. The Zaozigou gold deposit should be classified as an orogenic type gold deposit.
2024, 49(12): 4404-4417.
doi: 10.3799/dqkx.2024.072
Abstract:
Understanding the evolution of continental crust is crucial for comprehending the Earth's structure and exploring the development of plate tectonics and orogenic belts. In convergent plate margins, large-scale igneous rocks are generated, and their geochemical features are closely related to their formation depth. Consequently, these rocks are widely used in reconstructing crustal thickness and interpreting paleoaltitudes in orogenic belts. In this paper it reviews the establishment and development of methods that utilize geochemical information to investigate crustal thickness. It evaluates the advantages, disadvantages, and applications of various methods, and summarizes their use in different orogenic belts and their role in paleoaltitude reconstruction. As a complement to quantitative paleoaltimetric techniques, the geochemical approach provides more continuous reflections of crustal thickness over time. Combined with rapidly accumulating geochemical databases, this method can offer deeper insights into paleoaltitude estimates, and the tectonic evolution of orogenic belts, and effectively promote the development of Earth system science.
Understanding the evolution of continental crust is crucial for comprehending the Earth's structure and exploring the development of plate tectonics and orogenic belts. In convergent plate margins, large-scale igneous rocks are generated, and their geochemical features are closely related to their formation depth. Consequently, these rocks are widely used in reconstructing crustal thickness and interpreting paleoaltitudes in orogenic belts. In this paper it reviews the establishment and development of methods that utilize geochemical information to investigate crustal thickness. It evaluates the advantages, disadvantages, and applications of various methods, and summarizes their use in different orogenic belts and their role in paleoaltitude reconstruction. As a complement to quantitative paleoaltimetric techniques, the geochemical approach provides more continuous reflections of crustal thickness over time. Combined with rapidly accumulating geochemical databases, this method can offer deeper insights into paleoaltitude estimates, and the tectonic evolution of orogenic belts, and effectively promote the development of Earth system science.
2024, 49(12): 4418-4433.
doi: 10.3799/dqkx.2023.171
Abstract:
The polarity of Early Paleozoic ocean-continent transformation in South Altun has been an issue recently. However, detailed petrological evidence for the exhumation of the deep subducted continental crust is still lacking. In this paper, it researches petrological, geochemical, zircon U-Pb chronological and Lu-Hf isotopic characteristics of the northern Manya complex, to discuss its source and tectonic environment, and reveal magmatic response to the Early Paleozoic tectonic evolution. The 458-420 Ma granites have similar material source and magmatic source, resulting from the similar ranges of εHf (t) and tDM2 values, and shoshonitic characteristics such as rich in alkali and K, and lack of Ti and Fe. The 458-453 Ma granites were formed by decompression melting of deep-subducted continental crust, which were transported to the upper crust by exhumation. The 451-420 Ma granites were product of partial melting of lower crustal materials triggered by underplating of mantle-derived magma in a post-collisional extensional environment. Thus, exhumation of the deep-subducted continental crust completed at < 453 Ma, and the orogenic belt were in late orogenic post-collisional environment at < 451 Ma.
The polarity of Early Paleozoic ocean-continent transformation in South Altun has been an issue recently. However, detailed petrological evidence for the exhumation of the deep subducted continental crust is still lacking. In this paper, it researches petrological, geochemical, zircon U-Pb chronological and Lu-Hf isotopic characteristics of the northern Manya complex, to discuss its source and tectonic environment, and reveal magmatic response to the Early Paleozoic tectonic evolution. The 458-420 Ma granites have similar material source and magmatic source, resulting from the similar ranges of εHf (t) and tDM2 values, and shoshonitic characteristics such as rich in alkali and K, and lack of Ti and Fe. The 458-453 Ma granites were formed by decompression melting of deep-subducted continental crust, which were transported to the upper crust by exhumation. The 451-420 Ma granites were product of partial melting of lower crustal materials triggered by underplating of mantle-derived magma in a post-collisional extensional environment. Thus, exhumation of the deep-subducted continental crust completed at < 453 Ma, and the orogenic belt were in late orogenic post-collisional environment at < 451 Ma.
2024, 49(12): 4434-4449.
doi: 10.3799/dqkx.2024.062
Abstract:
The Diancangshan-Ailaoshan tectonic belt in the West Yunnan has developed numerous Precambrian rocks and thus provides an ideal window for revealing the Precambrian tectonic history of the southwestern margin of the Yangtze block. In this study, elemental geochemistry and isotopic geochronology of gabbro in the Diancangshan area are presented. The results show that the intrusion age of the gabbro is 771-769 Ma, indicating that Neoproterozoic mafic magmatic activity developed in the Diancangshan area. The gabbro of the Diancangshan area exhibits a variation in total alkali content (K2O+Na2O) of 4.40%-4.49%, with low Na2O/K2O ratios (2.30-2.34), and thus belongs to the calc-alkaline series. The samples have relatively high contents of Fe2O3t (7.36%-7.50%), MgO (7.15%-7.30%), and Mg# (69.46-69.52). They are characterized by enrichment in large ion lithophile elements (LILE) such as Rb, Ba, and Sr, and depletion in high field strength elements (HFSE) such as Nb, Ta, and Ti. The samples display a relative enrichment of light rare earth elements with a pronounced fractionation between light and heavy rare earth elements, and have slightly positive anomalies of Eu (Eu/Eu*=1.17-1.29), They have depleted zircon Hf isotopic compositions with positive εHf(t) values of 6.72-10.84.Comprehensive data show that the gabbro formed in back-arc basin environment and is the product of partial melting of mantle wedge peridotite that was metasomated by subducted fluid. During the Neoproterozoic, arc-basin system was developed at the southwestern Yangtze Block, and the South China located at the margin of the Rodinia Supercontinent during this period.
The Diancangshan-Ailaoshan tectonic belt in the West Yunnan has developed numerous Precambrian rocks and thus provides an ideal window for revealing the Precambrian tectonic history of the southwestern margin of the Yangtze block. In this study, elemental geochemistry and isotopic geochronology of gabbro in the Diancangshan area are presented. The results show that the intrusion age of the gabbro is 771-769 Ma, indicating that Neoproterozoic mafic magmatic activity developed in the Diancangshan area. The gabbro of the Diancangshan area exhibits a variation in total alkali content (K2O+Na2O) of 4.40%-4.49%, with low Na2O/K2O ratios (2.30-2.34), and thus belongs to the calc-alkaline series. The samples have relatively high contents of Fe2O3t (7.36%-7.50%), MgO (7.15%-7.30%), and Mg# (69.46-69.52). They are characterized by enrichment in large ion lithophile elements (LILE) such as Rb, Ba, and Sr, and depletion in high field strength elements (HFSE) such as Nb, Ta, and Ti. The samples display a relative enrichment of light rare earth elements with a pronounced fractionation between light and heavy rare earth elements, and have slightly positive anomalies of Eu (Eu/Eu*=1.17-1.29), They have depleted zircon Hf isotopic compositions with positive εHf(t) values of 6.72-10.84.Comprehensive data show that the gabbro formed in back-arc basin environment and is the product of partial melting of mantle wedge peridotite that was metasomated by subducted fluid. During the Neoproterozoic, arc-basin system was developed at the southwestern Yangtze Block, and the South China located at the margin of the Rodinia Supercontinent during this period.
2024, 49(12): 4450-4464.
doi: 10.3799/dqkx.2024.084
Abstract:
To unravel the difference of rift evolution between the sub- and supra-T85 horizon, and illustrate the formation mechanism of the tectonic transition, the rift architecture, fault activity and spatio-temporal variations of subsidence were investigated by using high-quality seismic data and borehole data. Dividing by the T85 angular unconformity, the Lishui depression exhibits two distinct rift architecture: the underlying fault-controlled, wedge-shaped packages and the overlying saucer-shaped packages. Subsidence within the Lishui depression migrated westward during the faulting stage, while it progressively migrated eastward during the subsequent faulting and sagging stage. Together with the regional geodynamic context and advances in rift research, the study proposes that either the thermal subsidence caused by tectonic migration or the shallow response to the ductile deformation of lower crust resulted in the tectonic transition within the Lishui depression. The study significantly improves the understanding of rift evolution and its controlling factors.
To unravel the difference of rift evolution between the sub- and supra-T85 horizon, and illustrate the formation mechanism of the tectonic transition, the rift architecture, fault activity and spatio-temporal variations of subsidence were investigated by using high-quality seismic data and borehole data. Dividing by the T85 angular unconformity, the Lishui depression exhibits two distinct rift architecture: the underlying fault-controlled, wedge-shaped packages and the overlying saucer-shaped packages. Subsidence within the Lishui depression migrated westward during the faulting stage, while it progressively migrated eastward during the subsequent faulting and sagging stage. Together with the regional geodynamic context and advances in rift research, the study proposes that either the thermal subsidence caused by tectonic migration or the shallow response to the ductile deformation of lower crust resulted in the tectonic transition within the Lishui depression. The study significantly improves the understanding of rift evolution and its controlling factors.
2024, 49(12): 4465-4482.
doi: 10.3799/dqkx.2024.028
Abstract:
The field of energy geology mainly focuses on geological porous materials (such as minerals, rocks, and soil) as research targets which are applied to conventional and unconventional oil and gas exploration and development, traditional and critical mineral exploitation, geothermal energy utilization, carbon dioxide capture and storage, radioactive nuclear waste storage, and hydrogen energy storage and utilization. However, with the routine research methods to study the properties of porous media materials entering the bottleneck period in theory and technology, the high-flux large scientific devices represented by X-ray scattering have gradually emerged, opening up a new method for non-destructive characterization of geological porous media materials from nm to cm size structure two-dimensional and three-dimensional characterization. Since X-ray scattering has not been widely used in the field of energy geology, in this paper it introduces the basic principle of X-ray scattering, its application history, examples in the field of energy geology, and synchrotron radiation stations in China and abroad for energy geologists. Besides, in this paper it proposes the prospect of X-ray scattering in the field of geological porous media characterization to promote the research of X-ray scattering in the field of energy geology and its wide application.
The field of energy geology mainly focuses on geological porous materials (such as minerals, rocks, and soil) as research targets which are applied to conventional and unconventional oil and gas exploration and development, traditional and critical mineral exploitation, geothermal energy utilization, carbon dioxide capture and storage, radioactive nuclear waste storage, and hydrogen energy storage and utilization. However, with the routine research methods to study the properties of porous media materials entering the bottleneck period in theory and technology, the high-flux large scientific devices represented by X-ray scattering have gradually emerged, opening up a new method for non-destructive characterization of geological porous media materials from nm to cm size structure two-dimensional and three-dimensional characterization. Since X-ray scattering has not been widely used in the field of energy geology, in this paper it introduces the basic principle of X-ray scattering, its application history, examples in the field of energy geology, and synchrotron radiation stations in China and abroad for energy geologists. Besides, in this paper it proposes the prospect of X-ray scattering in the field of geological porous media characterization to promote the research of X-ray scattering in the field of energy geology and its wide application.
2024, 49(12): 4483-4500.
doi: 10.3799/dqkx.2024.910
Abstract:
In 2020, the Ping'an 1 well in the northeastern part of Sichuan Basin tested 112.8 m3/d in the Jurassic Lianggaoshan Formation shale, making a breakthrough in shale oil exploration. However, the daily oil production of other Wells deployed in succession is very different, and the exploration and development effect are not ideal, which restricts the selection of shale oil rich areas. In response, in this paper, the oil sweet spot parameter (free oil amount) is obtained based on the improved ΔlogR method and the formation free oil recovery model, the physical property sweet spot parameter (porosity) is obtained by multiple linear regression analysis, the elastic energy sweet spot parameter (formation pressure coefficient) is predicted by Bowers method, the brittleness index predicted by comprehensive random forest algorithm and the Young's modulus obtained by mathematical model. By adopting an improved analytic hierarchy method, the comprehensive evaluation index of the sweet spot is obtained and applied to key shale oil exploration wells. It is considered that the potential favorable intervals of PY1 and PA1 wells are distributed in the bottom of Liangshang1, the bottom of Liangshang2 and the middle of Liangshang3, and the YQ1 well is distributed in the middle bottom of Liangshang1, the bottom and the top of Liangshang3. The target areas of plane optimization are mainly concentrated in the north of PY1 and PA1 wells and near YQ1 wells.
In 2020, the Ping'an 1 well in the northeastern part of Sichuan Basin tested 112.8 m3/d in the Jurassic Lianggaoshan Formation shale, making a breakthrough in shale oil exploration. However, the daily oil production of other Wells deployed in succession is very different, and the exploration and development effect are not ideal, which restricts the selection of shale oil rich areas. In response, in this paper, the oil sweet spot parameter (free oil amount) is obtained based on the improved ΔlogR method and the formation free oil recovery model, the physical property sweet spot parameter (porosity) is obtained by multiple linear regression analysis, the elastic energy sweet spot parameter (formation pressure coefficient) is predicted by Bowers method, the brittleness index predicted by comprehensive random forest algorithm and the Young's modulus obtained by mathematical model. By adopting an improved analytic hierarchy method, the comprehensive evaluation index of the sweet spot is obtained and applied to key shale oil exploration wells. It is considered that the potential favorable intervals of PY1 and PA1 wells are distributed in the bottom of Liangshang1, the bottom of Liangshang2 and the middle of Liangshang3, and the YQ1 well is distributed in the middle bottom of Liangshang1, the bottom and the top of Liangshang3. The target areas of plane optimization are mainly concentrated in the north of PY1 and PA1 wells and near YQ1 wells.
2024, 49(12): 4501-4517.
doi: 10.3799/dqkx.2024.079
Abstract:
With the ongoing advancement of research on the coupling effect of unconventional oil and gas enrichment with multi-geological (biological) events, it has increasingly been confirmed that the deposition process of unconventional oil and gas "sweet spots" in black shale formations is frequently accompanied by volcanic eruptions, hydrothermal activities, ocean anoxia, climate change, biological prosperity, and extinctions, among various global or regional geological (biological) events. The Carboniferous-Permian transition in the eastern margin of the Ordos basin is endowed with multiple sets of marine-continental shale formations, which are significant targets for the exploration and development of shale gas in the country. In this paper it provides a review of the major geological events during the Carboniferous-Permian transition in order to discuss their potential impact on shale gas enrichment in the eastern margin of the Ordos basin. The Study shows that the changes in the glacial sea-level, paleoclimate during the Carboniferous-Permian transition have impacted on the surface primary productivity of organic matter and the bottom redox conditions in different degrees. Given the positive correlation between gas content and total organic carbon (TOC) content in the Carboniferous Jinci Section (Zhaoxian Shale) and Permian Shan23 Subsection shale formations in the eastern margin of the Ordos basin, it discusses the potential influence of paleoproductivity and paleoenvironment on the enrichment of marine-continental transition shale gas deposits: vegetation flourished organic matter, and with the relative rise in sea level, a hypoxic-anoxic water environment is easily formed, conducive to the deposition and enrichment of organic matter, thereby ultimately facilitating the formation of the "sweet spots" for shale gas in the region.
With the ongoing advancement of research on the coupling effect of unconventional oil and gas enrichment with multi-geological (biological) events, it has increasingly been confirmed that the deposition process of unconventional oil and gas "sweet spots" in black shale formations is frequently accompanied by volcanic eruptions, hydrothermal activities, ocean anoxia, climate change, biological prosperity, and extinctions, among various global or regional geological (biological) events. The Carboniferous-Permian transition in the eastern margin of the Ordos basin is endowed with multiple sets of marine-continental shale formations, which are significant targets for the exploration and development of shale gas in the country. In this paper it provides a review of the major geological events during the Carboniferous-Permian transition in order to discuss their potential impact on shale gas enrichment in the eastern margin of the Ordos basin. The Study shows that the changes in the glacial sea-level, paleoclimate during the Carboniferous-Permian transition have impacted on the surface primary productivity of organic matter and the bottom redox conditions in different degrees. Given the positive correlation between gas content and total organic carbon (TOC) content in the Carboniferous Jinci Section (Zhaoxian Shale) and Permian Shan23 Subsection shale formations in the eastern margin of the Ordos basin, it discusses the potential influence of paleoproductivity and paleoenvironment on the enrichment of marine-continental transition shale gas deposits: vegetation flourished organic matter, and with the relative rise in sea level, a hypoxic-anoxic water environment is easily formed, conducive to the deposition and enrichment of organic matter, thereby ultimately facilitating the formation of the "sweet spots" for shale gas in the region.
2024, 49(12): 4518-4529.
doi: 10.3799/dqkx.2024.065
Abstract:
Tight gas reservoir heterogeneity is strong and the effective reservoir prediction is difficult. In this paper, the main gas-producing layers within Carboniferous-Permian Formation in the southern Shenfu area were taken as the research object. The effective characteristics and the main controlling factors of effective reservoirs were studied by means of thin section observation, physical property test, mercury injection experiment and productivity analysis. The results show that the reservoirs are mainly composed of lithic sandstone and feldspar lithic sandstone with low porosity and permeability. Combined with productivity, the lower limit of reservoir physical properties can be manifest as 7% porosity and 0.1 mD permeability. Mercury intrusion-fractal characterization shows that the effective reservoir pores are mainly distributed in the range of 750-3 900 nm, accounting for more than 50%, corresponding to the dissolution pores. However, the tight reservoir pores are concentrated in the range of 0-80 nm, accounting for more than 80%, corresponding to the clay intercrystalline pores. The effectiveness of underwater distributary channel accounts for more than 70%, which is a high-energy facies belt for effective reservoir development, and can be proven by sorting and particle size analysis. The pore type is mainly the dissolution pore with secondary origin, accounting for more than 85%. Generally, the dissolution pore formed after the dissolution of feldspar by organic acids in the late diagenesis stage. The larger the amount of feldspar dissolution, the higher the porosity and permeability. Based on the above analysis, the coupling of high-energy microfacies and secondary dissolution is the main controlling factor of effective reservoir development.
Tight gas reservoir heterogeneity is strong and the effective reservoir prediction is difficult. In this paper, the main gas-producing layers within Carboniferous-Permian Formation in the southern Shenfu area were taken as the research object. The effective characteristics and the main controlling factors of effective reservoirs were studied by means of thin section observation, physical property test, mercury injection experiment and productivity analysis. The results show that the reservoirs are mainly composed of lithic sandstone and feldspar lithic sandstone with low porosity and permeability. Combined with productivity, the lower limit of reservoir physical properties can be manifest as 7% porosity and 0.1 mD permeability. Mercury intrusion-fractal characterization shows that the effective reservoir pores are mainly distributed in the range of 750-3 900 nm, accounting for more than 50%, corresponding to the dissolution pores. However, the tight reservoir pores are concentrated in the range of 0-80 nm, accounting for more than 80%, corresponding to the clay intercrystalline pores. The effectiveness of underwater distributary channel accounts for more than 70%, which is a high-energy facies belt for effective reservoir development, and can be proven by sorting and particle size analysis. The pore type is mainly the dissolution pore with secondary origin, accounting for more than 85%. Generally, the dissolution pore formed after the dissolution of feldspar by organic acids in the late diagenesis stage. The larger the amount of feldspar dissolution, the higher the porosity and permeability. Based on the above analysis, the coupling of high-energy microfacies and secondary dissolution is the main controlling factor of effective reservoir development.
2024, 49(12): 4530-4545.
doi: 10.3799/dqkx.2024.095
Abstract:
The role of cementing in the secure and steady exploitation of natural gas hydrates and other deepwater hydrocarbon resources is of paramount importance. In addressing the distinctive challenges posed by deepwater gas hydrate formations, such as low temperatures, minimal fracture pressures, the inclination towards hydrate dissociation, high-pressure shallow gas zones, and aqueous migration, a spectrum of cement slurry systems has been developed with innovation both domestically and internationally. This scholarly work presents an exhaustive overview of the contemporary research status concerning four pivotal cementing slurry technologies that are specifically adapted for hydrate formations. It conducts a rigorous analysis of the merits and limitations of cementing slurry systems characterized by low-temperature early-strength, low-density early-strength, low-heat generation, and anti-migration properties. Furthermore, it thoroughly investigates the applicability and promise of nascent cementing slurry technologies, which encompass insulating and thermal barrier cementing slurries, microbially induced self-healing cementing slurries, and salt-tolerant cementing slurries, for their utilization in hydrate formations. This contribution aims to furnish the latest understanding and insights into the progressive trajectory of cementing slurry technologies within natural gas hydrate formations, benefiting both researchers and professionals, and catalyzing the advancement of cementing technology in marine natural gas hydrate formations and contiguous scientific fields.
The role of cementing in the secure and steady exploitation of natural gas hydrates and other deepwater hydrocarbon resources is of paramount importance. In addressing the distinctive challenges posed by deepwater gas hydrate formations, such as low temperatures, minimal fracture pressures, the inclination towards hydrate dissociation, high-pressure shallow gas zones, and aqueous migration, a spectrum of cement slurry systems has been developed with innovation both domestically and internationally. This scholarly work presents an exhaustive overview of the contemporary research status concerning four pivotal cementing slurry technologies that are specifically adapted for hydrate formations. It conducts a rigorous analysis of the merits and limitations of cementing slurry systems characterized by low-temperature early-strength, low-density early-strength, low-heat generation, and anti-migration properties. Furthermore, it thoroughly investigates the applicability and promise of nascent cementing slurry technologies, which encompass insulating and thermal barrier cementing slurries, microbially induced self-healing cementing slurries, and salt-tolerant cementing slurries, for their utilization in hydrate formations. This contribution aims to furnish the latest understanding and insights into the progressive trajectory of cementing slurry technologies within natural gas hydrate formations, benefiting both researchers and professionals, and catalyzing the advancement of cementing technology in marine natural gas hydrate formations and contiguous scientific fields.
2024, 49(12): 4546-4563.
doi: 10.3799/dqkx.2024.003
Abstract:
Widespread development of microbiolites or microbial-associated deposits is a common sedimentological response to the aftermath of mass extinctions. Recent studies have suggested that the end-Middle Permian extinction was the sixth largest extinction event in geological history, but the record of microbial deposition after the extinction is still lacking. In this study, the oncoidal limestone at the bottom of Wujiaping Formation of Permian in Well HY3, Hongxing area, East Sichuan, was investigated in detail, and the sedimentary facies evolution of its related strata was also analyzed. From the top of Maokou Formation to the bottom of Changxing Formation in Well HY3, 5 sedimentary facies (assemblages) and 11 sedimentary microfacies are identified. The vertical evolution of sedimentary facies in Wujiaping Formation indicates three third-order sea level change cycles where the overall water depth gradually increases. The oncolite is only found in the mid-late transgression stage of the first sedimentary cycle of Wujiaping stage. Based on the characteristics of core and lamination, the oncoids of Wujiaping Formation can be divided into four types. With the increase of sedimentary water depth, the type parameters, diameter and density of oncoids present three distinct development stages from the bottom upward. The changes of these parameters indicate that suitable hydrodynamic conditions are one of the key factors for the development of oncoids. In addition, the development of oncoids may have been influenced by biological extinction and terrigenous inputs. The oncoidal horizon corresponds to the late Middle Permian extinction period, and the sharp decline of epigenetic biodiversity provides sufficient ecological space for the development of oncolite induced by microbes. In the adjacent strata above the oncoidal limestone or in similar water depth conditions, the terrigenous input may be enhanced due to the closer proximity to coal, resulting in the disappearance of oncolite.
Widespread development of microbiolites or microbial-associated deposits is a common sedimentological response to the aftermath of mass extinctions. Recent studies have suggested that the end-Middle Permian extinction was the sixth largest extinction event in geological history, but the record of microbial deposition after the extinction is still lacking. In this study, the oncoidal limestone at the bottom of Wujiaping Formation of Permian in Well HY3, Hongxing area, East Sichuan, was investigated in detail, and the sedimentary facies evolution of its related strata was also analyzed. From the top of Maokou Formation to the bottom of Changxing Formation in Well HY3, 5 sedimentary facies (assemblages) and 11 sedimentary microfacies are identified. The vertical evolution of sedimentary facies in Wujiaping Formation indicates three third-order sea level change cycles where the overall water depth gradually increases. The oncolite is only found in the mid-late transgression stage of the first sedimentary cycle of Wujiaping stage. Based on the characteristics of core and lamination, the oncoids of Wujiaping Formation can be divided into four types. With the increase of sedimentary water depth, the type parameters, diameter and density of oncoids present three distinct development stages from the bottom upward. The changes of these parameters indicate that suitable hydrodynamic conditions are one of the key factors for the development of oncoids. In addition, the development of oncoids may have been influenced by biological extinction and terrigenous inputs. The oncoidal horizon corresponds to the late Middle Permian extinction period, and the sharp decline of epigenetic biodiversity provides sufficient ecological space for the development of oncolite induced by microbes. In the adjacent strata above the oncoidal limestone or in similar water depth conditions, the terrigenous input may be enhanced due to the closer proximity to coal, resulting in the disappearance of oncolite.
2024, 49(12): 4564-4575.
doi: 10.3799/dqkx.2024.042
Abstract:
Valley road is an artistic treasure that integrates natural resources, cultural history, and leisure and recreation, carrying multiple functions such as the ecological foundation, economic pillar, and social need. However, the analysis of the individual characteristics of valley road is not comprehensive, and the positioning of its service functions is not clear, which seriously affects the scientific management of valley road and restricts the sustainable development of the Qinling Mountains. On the basis of elucidating the definition and connotation of valley road, in this paper it elaborates on the three major meanings of facilitating interdisciplinary integration and development, assisting in the construction of a livable environment for humans, and promoting the implementation of regional strategies in the study of valley road typology, and summarizes the research progress of valley road classification. Focusing on the three major service functions of ecology, economy, and society of the valley road, a hierarchical model based on the concept of Ecological-Economic-Social Collaborative Development (EESCD) is constructed. An evaluation procedure for the major function of valley road is designed, and its main service function is determined. Combining the upper level planning, a reasonable type, orderly division of labor, and distinctive feature classification system for valley road has been established, and its naming form based on "protection zone type-main service function-management measure" has been determined, which assists in the diversified management of valley road and the deep exploration of its natural resources and cultural connotations in the northern foothills of Qinling Mountains, thereby, provides reference and guidance for the development, utilization, and protection of valley road.
Valley road is an artistic treasure that integrates natural resources, cultural history, and leisure and recreation, carrying multiple functions such as the ecological foundation, economic pillar, and social need. However, the analysis of the individual characteristics of valley road is not comprehensive, and the positioning of its service functions is not clear, which seriously affects the scientific management of valley road and restricts the sustainable development of the Qinling Mountains. On the basis of elucidating the definition and connotation of valley road, in this paper it elaborates on the three major meanings of facilitating interdisciplinary integration and development, assisting in the construction of a livable environment for humans, and promoting the implementation of regional strategies in the study of valley road typology, and summarizes the research progress of valley road classification. Focusing on the three major service functions of ecology, economy, and society of the valley road, a hierarchical model based on the concept of Ecological-Economic-Social Collaborative Development (EESCD) is constructed. An evaluation procedure for the major function of valley road is designed, and its main service function is determined. Combining the upper level planning, a reasonable type, orderly division of labor, and distinctive feature classification system for valley road has been established, and its naming form based on "protection zone type-main service function-management measure" has been determined, which assists in the diversified management of valley road and the deep exploration of its natural resources and cultural connotations in the northern foothills of Qinling Mountains, thereby, provides reference and guidance for the development, utilization, and protection of valley road.
2024, 49(12): 4576-4593.
doi: 10.3799/dqkx.2023.196
Abstract:
Identifying geothermal property characteristics and accurately assessing geothermal resource potential are crucial foundations for achieving precise zoning and large-scale, efficient development and utilization of geothermal energy. Xiong'an New Area, one of the typical low-temperature geothermal systems in the North China plain, is selected as the study area. The study aims to obtain the thermal reservoir properties of the Wumishan Formation, predict the three-dimensional temperature distribution, improve the resource assessment algorithm, and evaluate the geothermal resource potential under heterogeneous conditions for various thermal properties and stratigraphic parameters. The research results indicate that the geothermal resource quantity of the Wumishan Formation above 5 000 m is equivalent to 3.219 5×105 million tons of standard coal. Using the balanced injection and production method, the calculated extractable geothermal fluid resource quantity is 436.64×106 m3 per year, equivalent to 508.217 4 thousand tons of standard coal in extractable heat. The extractable resource quantity and heat calculated by the balanced injection and production method are 48.7 times and 50.3 times greater, respectively, than those calculated using the extraction coefficient method. The geothermal resource per unit area and the geothermal fluid resource per unit area are the largest in the Rongcheng area. The calculated resource indicators under heterogeneous conditions are 2.29 to 2.95 times higher than those under homogeneous conditions.
Identifying geothermal property characteristics and accurately assessing geothermal resource potential are crucial foundations for achieving precise zoning and large-scale, efficient development and utilization of geothermal energy. Xiong'an New Area, one of the typical low-temperature geothermal systems in the North China plain, is selected as the study area. The study aims to obtain the thermal reservoir properties of the Wumishan Formation, predict the three-dimensional temperature distribution, improve the resource assessment algorithm, and evaluate the geothermal resource potential under heterogeneous conditions for various thermal properties and stratigraphic parameters. The research results indicate that the geothermal resource quantity of the Wumishan Formation above 5 000 m is equivalent to 3.219 5×105 million tons of standard coal. Using the balanced injection and production method, the calculated extractable geothermal fluid resource quantity is 436.64×106 m3 per year, equivalent to 508.217 4 thousand tons of standard coal in extractable heat. The extractable resource quantity and heat calculated by the balanced injection and production method are 48.7 times and 50.3 times greater, respectively, than those calculated using the extraction coefficient method. The geothermal resource per unit area and the geothermal fluid resource per unit area are the largest in the Rongcheng area. The calculated resource indicators under heterogeneous conditions are 2.29 to 2.95 times higher than those under homogeneous conditions.
2024, 49(12): 4594-4607.
doi: 10.3799/dqkx.2024.081
Abstract:
As one of the largest carbon "reservoirs" in the world, the role of mines in the global carbon cycle has attracted much attention. In this study it aims to systematically sort out and deeply analyze the roles and mechanisms of mine ecological restoration in carbon sequestration and carbon neutrality. At the same time, it concludes the methods for assessing carbon sequestration potentials, to provide a scientific basis for formulating mine ecological restoration measures aimed at ecological restoration and carbon sequestration, and help to accelerate the achievement of the "dual-carbon" goal. In this study establishes a conceptual model of the carbon cycle in the mining ecosystem. Based on the principles of mine ecological restoration, it discusses three major restoration measures, including topographic and geomorphic remodeling, soil reconstruction and revegetation, and their carbon sequestration mechanisms, as well as the keys in their implementation. Besides, this study summarizes the carbon sequestration potential assessment model and method. The next step of the study should be to optimize the restoration measures and improve the accuracy of carbon sequestration assessment based on sustainable development, to prolong the maintenance time of the ecological benefits of mine restoration and contribute to the sustainable development of carbon sequestration capacity of mine ecosystems.
As one of the largest carbon "reservoirs" in the world, the role of mines in the global carbon cycle has attracted much attention. In this study it aims to systematically sort out and deeply analyze the roles and mechanisms of mine ecological restoration in carbon sequestration and carbon neutrality. At the same time, it concludes the methods for assessing carbon sequestration potentials, to provide a scientific basis for formulating mine ecological restoration measures aimed at ecological restoration and carbon sequestration, and help to accelerate the achievement of the "dual-carbon" goal. In this study establishes a conceptual model of the carbon cycle in the mining ecosystem. Based on the principles of mine ecological restoration, it discusses three major restoration measures, including topographic and geomorphic remodeling, soil reconstruction and revegetation, and their carbon sequestration mechanisms, as well as the keys in their implementation. Besides, this study summarizes the carbon sequestration potential assessment model and method. The next step of the study should be to optimize the restoration measures and improve the accuracy of carbon sequestration assessment based on sustainable development, to prolong the maintenance time of the ecological benefits of mine restoration and contribute to the sustainable development of carbon sequestration capacity of mine ecosystems.
2024, 49(12): 4608-4621.
doi: 10.3799/dqkx.2023.197
Abstract:
Global warming is expanding the frequency, scope, duration, and severity of severe drought and heavy rainfall events. Extreme climate events such as high temperatures, droughts, and heavy rainfall have significantly changed the rate and intensity of soil organic carbon mineralization and inorganic carbon release. The release of soil CO2, as an important component of the carbon cycle in terrestrial ecosystems, is highly sensitive to climate change. Exploring the relationship and response mechanism between soil CO2 release and climate change can provide theoretical support for in-depth understanding of soil carbon cycling and source sink mechanisms in the context of global warming. In this paper systematically it analyzes the previous studies on the effects of warming and precipitation changes on soil respiration (Rs) and soil carbonate mineral dissolution, and analyzed the impact of warming and precipitation changes on soil CO2 release from the aspects of Rs and soil carbonate mineral dissolution. In the future, efforts should be done to strengthen research on the coupling effects of climate change and other factors such as soil properties, nutrient content and availability, and microbial biomass and activity on Rs. Constructing an Rs rate model with multivariate factor coupling under extreme climate conditions. Deeply explore the response thresholds of Rs and carbonate mineral dissolution in carbonate bedrock soil areas to extreme heavy precipitation events. Accurately quantify the carbon migration and transformation flux between Rs and carbonate mineral dissolution under extreme heavy rainfall conditions.
Global warming is expanding the frequency, scope, duration, and severity of severe drought and heavy rainfall events. Extreme climate events such as high temperatures, droughts, and heavy rainfall have significantly changed the rate and intensity of soil organic carbon mineralization and inorganic carbon release. The release of soil CO2, as an important component of the carbon cycle in terrestrial ecosystems, is highly sensitive to climate change. Exploring the relationship and response mechanism between soil CO2 release and climate change can provide theoretical support for in-depth understanding of soil carbon cycling and source sink mechanisms in the context of global warming. In this paper systematically it analyzes the previous studies on the effects of warming and precipitation changes on soil respiration (Rs) and soil carbonate mineral dissolution, and analyzed the impact of warming and precipitation changes on soil CO2 release from the aspects of Rs and soil carbonate mineral dissolution. In the future, efforts should be done to strengthen research on the coupling effects of climate change and other factors such as soil properties, nutrient content and availability, and microbial biomass and activity on Rs. Constructing an Rs rate model with multivariate factor coupling under extreme climate conditions. Deeply explore the response thresholds of Rs and carbonate mineral dissolution in carbonate bedrock soil areas to extreme heavy precipitation events. Accurately quantify the carbon migration and transformation flux between Rs and carbonate mineral dissolution under extreme heavy rainfall conditions.
2024, 49(12): 4622-4634.
doi: 10.3799/dqkx.2023.204
Abstract:
The water cycle in the tropical regions is the important driving force for the evolution of the global climate system, and Hainan Province is the only tropical island province in China, which is an ideal area for the study of tropical water vapor cycle. Hydrogen and oxygen stable isotopes in water are important method for water cycle research. In this study, the transport path and source of water vapor in Hainan Island are studied through the spatial distribution of stable isotopes of major rivers in Hainan Island. The isotopes of the river water of Hainan Island are gradually positive from west to east in the latitude direction, and are symmetrically distributed in the longitude direction. The isotopes of the southeastern river of Hainan Island show the "altitude effect", while the isotopes of the Changhua River in southwestern Hainan Island show the "anti-altitude effect". The spatial distribution of river water isotopes in Hainan Island shows that topography is the most important factor controlling the spatial distribution of river water isotopes, and the eastern part of Hainan Island is the windward slope of water vapor transport, while the west is in the "rain shadow area", and water vapor is transported from east to west.
The water cycle in the tropical regions is the important driving force for the evolution of the global climate system, and Hainan Province is the only tropical island province in China, which is an ideal area for the study of tropical water vapor cycle. Hydrogen and oxygen stable isotopes in water are important method for water cycle research. In this study, the transport path and source of water vapor in Hainan Island are studied through the spatial distribution of stable isotopes of major rivers in Hainan Island. The isotopes of the river water of Hainan Island are gradually positive from west to east in the latitude direction, and are symmetrically distributed in the longitude direction. The isotopes of the southeastern river of Hainan Island show the "altitude effect", while the isotopes of the Changhua River in southwestern Hainan Island show the "anti-altitude effect". The spatial distribution of river water isotopes in Hainan Island shows that topography is the most important factor controlling the spatial distribution of river water isotopes, and the eastern part of Hainan Island is the windward slope of water vapor transport, while the west is in the "rain shadow area", and water vapor is transported from east to west.
2024, 49(12): 4635-4658.
doi: 10.3799/dqkx.2024.124
Abstract:
Large and extremely large landslides along the active tectonic zones are complex and hazardous. Previous researches on these landslides development characteristics, disaster backgrounds, and formation mechanisms have primarily focused on factors such as rainfall, stratigraphic lithology, and seismic activity. However, studies on the endogenic dynamic control of disaster backgrounds and formation mechanisms have remained challenging for both the academic and engineering communities. Based on remote sensing interpretation, data collection, field investigations, and analysis of typical landslide cases, this study established a geological hazard database for the eastern Tibetan Plateau along the Sichuan-Xizang transportation corridor and proposes a regional crustal stability assessment method that considers terrain relief. The study reveals that about 62% of geological hazards occur in the unstable crustal areas and relatively unstable crustal areas, where endogenous geological conditions significantly influence the spatial and temporal distribution of geological hazards. The development and distribution of large landslides are significantly controlled by active tectonic zones, displaying four characteristics: complex geological structures fostering large landslides, specific geotechnical structures controlling large landslides, strong seismic activities inducing large landslides, and continuous fault creep promoting catastrophic landslides. These characteristics contribute to a complex disaster evolution process that includes disaster fostering, control, induction, and promotion within active tectonic zones. The research findings are vitally important for understanding the formation mechanisms of large and extremely large landslides on the Tibetan Plateau and enhancing research on risk prevention for these landslides.
Large and extremely large landslides along the active tectonic zones are complex and hazardous. Previous researches on these landslides development characteristics, disaster backgrounds, and formation mechanisms have primarily focused on factors such as rainfall, stratigraphic lithology, and seismic activity. However, studies on the endogenic dynamic control of disaster backgrounds and formation mechanisms have remained challenging for both the academic and engineering communities. Based on remote sensing interpretation, data collection, field investigations, and analysis of typical landslide cases, this study established a geological hazard database for the eastern Tibetan Plateau along the Sichuan-Xizang transportation corridor and proposes a regional crustal stability assessment method that considers terrain relief. The study reveals that about 62% of geological hazards occur in the unstable crustal areas and relatively unstable crustal areas, where endogenous geological conditions significantly influence the spatial and temporal distribution of geological hazards. The development and distribution of large landslides are significantly controlled by active tectonic zones, displaying four characteristics: complex geological structures fostering large landslides, specific geotechnical structures controlling large landslides, strong seismic activities inducing large landslides, and continuous fault creep promoting catastrophic landslides. These characteristics contribute to a complex disaster evolution process that includes disaster fostering, control, induction, and promotion within active tectonic zones. The research findings are vitally important for understanding the formation mechanisms of large and extremely large landslides on the Tibetan Plateau and enhancing research on risk prevention for these landslides.
2024, 49(12): 4659-4672.
doi: 10.3799/dqkx.2024.040
Abstract:
High-altitude and long-runout landslides exhibit typical characteristics including slip initiation at high altitudes, rapid sliding speeds, and intense dynamic shearing. These landslides exhibit differences in their long runout mechanisms due to variations in saturation characteristics of loose layers along their sliding path during high-speed sliding. This study examines the Luanshibao landslide in Litang County, Sichuan Province, which has a runout zone composed of saturated deposit. After a comprehensive investigation and analysis of the landslide characteristics, it conducted high-speed undrained ring shear tests at various normal stress levels of 200 kPa, 400 kPa, and 600 kPa using an ICL-2 high-speed ring shear apparatus. The test shearing speed was maintained at 50 cm/s, with a shearing distance of 300 m. The experimental findings indicate that the formation of the sliding zone can be divided into four stages: initial dilation, dilation-negative dilation, unreal dilation, and compression drainage. The pore water pressure increases nonlinearly and has a positive correlation with the normal displacement. When the shear distance reaches 100 m, the pore water pressure increases to more than 50% of the total normal stress. Sliding zone liquefaction caused by particle breakage is the main reason for the reduction in shear strength, leading to shear strength decreases by more than 50% and the pore water pressure increases to more than 70% of the total normal stress. The formation process of the Luanshibao landslide can be summarized as follows: seismic activity triggered high-speed sliding initiation, landslide body fragmentation formed a debris flow, sliding zone liquefaction facilitated long runout movement, and debris flow slowed and accumulated. The research findings could provide a reference for the analysis of the mechanisms of high-altitude and long-runout landslides with water saturated loose layers in their movement paths.
High-altitude and long-runout landslides exhibit typical characteristics including slip initiation at high altitudes, rapid sliding speeds, and intense dynamic shearing. These landslides exhibit differences in their long runout mechanisms due to variations in saturation characteristics of loose layers along their sliding path during high-speed sliding. This study examines the Luanshibao landslide in Litang County, Sichuan Province, which has a runout zone composed of saturated deposit. After a comprehensive investigation and analysis of the landslide characteristics, it conducted high-speed undrained ring shear tests at various normal stress levels of 200 kPa, 400 kPa, and 600 kPa using an ICL-2 high-speed ring shear apparatus. The test shearing speed was maintained at 50 cm/s, with a shearing distance of 300 m. The experimental findings indicate that the formation of the sliding zone can be divided into four stages: initial dilation, dilation-negative dilation, unreal dilation, and compression drainage. The pore water pressure increases nonlinearly and has a positive correlation with the normal displacement. When the shear distance reaches 100 m, the pore water pressure increases to more than 50% of the total normal stress. Sliding zone liquefaction caused by particle breakage is the main reason for the reduction in shear strength, leading to shear strength decreases by more than 50% and the pore water pressure increases to more than 70% of the total normal stress. The formation process of the Luanshibao landslide can be summarized as follows: seismic activity triggered high-speed sliding initiation, landslide body fragmentation formed a debris flow, sliding zone liquefaction facilitated long runout movement, and debris flow slowed and accumulated. The research findings could provide a reference for the analysis of the mechanisms of high-altitude and long-runout landslides with water saturated loose layers in their movement paths.
2024, 49(12): 4673-4689.
doi: 10.3799/dqkx.2023.075
Abstract:
In order to study the influence of the dynamic response of the soil around the tunnel under the train load in the small radius curve section, the pore water pressure and water level were measured in the field, and the numerical analysis was performed using the finite element software MIDAS. The results show that the vibration load is the important reason for the change of pore water pressure during the operation of the tunnel, the deeper the hole pressure gradually decreases; the closer to the tunnel, the more sensitive is the response to the train vibration dynamic response, the change amplitude and rate of pore water pressure and vertical deformation peak of the water in the soil are larger; the dynamic response of the soil at the bottom of the small radius curve tunnel increases with the train speed; the superpore water pressure generated by the soil is gradually dissipated, it can be predicted that the deformation damage to the surrounding soil with the train vibration.
In order to study the influence of the dynamic response of the soil around the tunnel under the train load in the small radius curve section, the pore water pressure and water level were measured in the field, and the numerical analysis was performed using the finite element software MIDAS. The results show that the vibration load is the important reason for the change of pore water pressure during the operation of the tunnel, the deeper the hole pressure gradually decreases; the closer to the tunnel, the more sensitive is the response to the train vibration dynamic response, the change amplitude and rate of pore water pressure and vertical deformation peak of the water in the soil are larger; the dynamic response of the soil at the bottom of the small radius curve tunnel increases with the train speed; the superpore water pressure generated by the soil is gradually dissipated, it can be predicted that the deformation damage to the surrounding soil with the train vibration.
2024, 49(12): 4690-4700.
doi: 10.3799/dqkx.2023.157
Abstract:
During the water level fluctuation period of the Three Gorges reservoir area, the seepage stress coupling characteristics of the geotechnical body in the landslide have a great influence on the stability of the landslide. In this paper, a one-dimensional seepage test was conducted on the sliding-zone soil of Majiagou landslide. It tested the relationship between the seepage velocity of the soil and the hydraulic gradient and found the seepage characteristics of the seepage pressure p loading and unloading process. It also performed triaxial consolidation tests under steady-state and cyclical p and analyzed the effects of the confining pressure σ3, the amplitude of the p, and the loading process on the permeability coefficient k and the volume strain. The following conclusions were drawn. (1) During the loading process, the seepage flow in the soil conforms to Darcy's law when the p was less than a certain threshold value, and the seepage flow shows nonlinearity when the p exceeds the threshold. The seepage flow conforms to Darcy's law when the p was unloaded. (2) When under a steady p, the k of soil is linear to the logarithm of the σ3. Its instantaneous modulus influence coefficient decreases exponentially when the p increases. (3) When under a cyclical p, the k of soil decreased exponentially as the number of fluctuations increases. And a rebound effect of expansion and then compression appears in the specimens in each cycle. The rebound of accumulated deformation occurs at a certain time point, which is almost consistent with the threshold value in the fitting function of the k and the number of cycles under the same conditions.
During the water level fluctuation period of the Three Gorges reservoir area, the seepage stress coupling characteristics of the geotechnical body in the landslide have a great influence on the stability of the landslide. In this paper, a one-dimensional seepage test was conducted on the sliding-zone soil of Majiagou landslide. It tested the relationship between the seepage velocity of the soil and the hydraulic gradient and found the seepage characteristics of the seepage pressure p loading and unloading process. It also performed triaxial consolidation tests under steady-state and cyclical p and analyzed the effects of the confining pressure σ3, the amplitude of the p, and the loading process on the permeability coefficient k and the volume strain. The following conclusions were drawn. (1) During the loading process, the seepage flow in the soil conforms to Darcy's law when the p was less than a certain threshold value, and the seepage flow shows nonlinearity when the p exceeds the threshold. The seepage flow conforms to Darcy's law when the p was unloaded. (2) When under a steady p, the k of soil is linear to the logarithm of the σ3. Its instantaneous modulus influence coefficient decreases exponentially when the p increases. (3) When under a cyclical p, the k of soil decreased exponentially as the number of fluctuations increases. And a rebound effect of expansion and then compression appears in the specimens in each cycle. The rebound of accumulated deformation occurs at a certain time point, which is almost consistent with the threshold value in the fitting function of the k and the number of cycles under the same conditions.
