2025 Vol. 50, No. 6
Display Method:
2025, 50(6): 2083-2106.
doi: 10.3799/dqkx.2024.157
PDF 11226KB
Abstract:
Dispersed metals such as gallium (Ga), germanium (Ge) and indium (In) play significant roles in high-tech development and national defense construction and have been classified as strategic and critical metals in China, USA and Europe. Pb-Zn deposits are not only the primary source of lead and zinc non-ferrous metals, but also rich in dispersed metal resources. The Qinling orogenic belt is an important Pb-Zn resource-producing area in China. Research on dispersed metals in the Pb-Zn deposits of this area is relatively weak, and there is a lack of systematic evaluation of dispersed metal resources. This study selected 19 representative Pb-Zn deposits in the West Qinling and East Qinling districts as the research objects. The trace element composition of sphalerite from different deposits determined using LA-ICP-MS with previous analytical data were summarized to reveal the contents and occurrences of dispersed metals Ga, Ge, In, and Cd. The research results indicate that the contents of Ga and Ge in sphalerite from Pb-Zn deposits in the West Qinling district are slightly higher than those in the East Qinling district. Among them, the Ga content in the Lengshuibeigou deposit is the highest (ave. ~210×10-6), and the Ge content in the Xitonggou deposit is the highest (ave. ~145×10-6) The contents of In and Cd in sphalerite from Pb-Zn deposits in the East Qinling district were significantly higher than those in the West Qinling district. Among them, the Luotuoshan deposit contains the highest In (ave. ~304×10-6) while the Poshan deposit contains the highest Cd (ave. ~7 186×10-6). With the exception of a few deposits that contained a small amount of independent Ge minerals, the dispersed metals Ga, Ge, In, and Cd in the Pb-Zn deposits of the Qinling orogenic belt mainly entered the sphalerite lattice in the form of isomorphism with Cu ions replacing Zn ions. Based on the results of this study and the zinc resource data of the deposits, the evaluation of dispersed metal resources in the Qinling orogenic belt was carried out using the mineral calculation method. The evaluation results demonstrate that the distribution of Ga resources in the Qinling orogenic belt is uneven. Among them, the Lengshuibeigou deposit in the East Qinling district has the highest Ga resources (~479 t). Ge resources are mainly distributed in the West Qinling district, with the Ge resource of the Luoba deposit being the highest (~190 t). In resources are concentrated in the East Qinling district, with the In resources of the Luotuoshan deposit being the highest (~450 t). The Cd resource in the Qinling orogenic belt is relatively abundant, with the Cd resources of the Changba-Lijiagou deposit reaching as high as 21 000 t. This study systematically identified the distribution patterns of dispersed metals Ga, Ge, In, and Cd in Pb-Zn deposits in the Qinling orogenic belt and conducted a preliminary resource evaluation, which holds significant guiding significance for the comprehensive utilization of associated dispersed metals in Pb-Zn deposits in the area.
Dispersed metals such as gallium (Ga), germanium (Ge) and indium (In) play significant roles in high-tech development and national defense construction and have been classified as strategic and critical metals in China, USA and Europe. Pb-Zn deposits are not only the primary source of lead and zinc non-ferrous metals, but also rich in dispersed metal resources. The Qinling orogenic belt is an important Pb-Zn resource-producing area in China. Research on dispersed metals in the Pb-Zn deposits of this area is relatively weak, and there is a lack of systematic evaluation of dispersed metal resources. This study selected 19 representative Pb-Zn deposits in the West Qinling and East Qinling districts as the research objects. The trace element composition of sphalerite from different deposits determined using LA-ICP-MS with previous analytical data were summarized to reveal the contents and occurrences of dispersed metals Ga, Ge, In, and Cd. The research results indicate that the contents of Ga and Ge in sphalerite from Pb-Zn deposits in the West Qinling district are slightly higher than those in the East Qinling district. Among them, the Ga content in the Lengshuibeigou deposit is the highest (ave. ~210×10-6), and the Ge content in the Xitonggou deposit is the highest (ave. ~145×10-6) The contents of In and Cd in sphalerite from Pb-Zn deposits in the East Qinling district were significantly higher than those in the West Qinling district. Among them, the Luotuoshan deposit contains the highest In (ave. ~304×10-6) while the Poshan deposit contains the highest Cd (ave. ~7 186×10-6). With the exception of a few deposits that contained a small amount of independent Ge minerals, the dispersed metals Ga, Ge, In, and Cd in the Pb-Zn deposits of the Qinling orogenic belt mainly entered the sphalerite lattice in the form of isomorphism with Cu ions replacing Zn ions. Based on the results of this study and the zinc resource data of the deposits, the evaluation of dispersed metal resources in the Qinling orogenic belt was carried out using the mineral calculation method. The evaluation results demonstrate that the distribution of Ga resources in the Qinling orogenic belt is uneven. Among them, the Lengshuibeigou deposit in the East Qinling district has the highest Ga resources (~479 t). Ge resources are mainly distributed in the West Qinling district, with the Ge resource of the Luoba deposit being the highest (~190 t). In resources are concentrated in the East Qinling district, with the In resources of the Luotuoshan deposit being the highest (~450 t). The Cd resource in the Qinling orogenic belt is relatively abundant, with the Cd resources of the Changba-Lijiagou deposit reaching as high as 21 000 t. This study systematically identified the distribution patterns of dispersed metals Ga, Ge, In, and Cd in Pb-Zn deposits in the Qinling orogenic belt and conducted a preliminary resource evaluation, which holds significant guiding significance for the comprehensive utilization of associated dispersed metals in Pb-Zn deposits in the area.
2025, 50(6): 2107-2123.
doi: 10.3799/dqkx.2025.046
Abstract:
To reveal the tectonic evolution of the Proto-Tethys and Paleo-Tethys Oceans and their genetic links to gold-polymetallic mineralization in the East Kunlun orogenic belt (EKOB), this study conducted petrographic, geochemical, and LA-ICP-MS zircon U-Pb geochronological analyses on monzogranite and granodiorite from the Mailong gold deposit. The results show that the monzogranite and granodiorite crystallized at 421±11 Ma (Late Silurian) and 228±4 Ma (Late Triassic), respectively, exhibiting metaluminous, high-potassium calc-alkaline characteristics. Trace element analyses reveal enrichment in light rare earth elements (LREE), large-ion lithophile elements (LILE: Rb, K), and incompatible elements (U, Th, Pb), with depletion in high-field-strength elements (HFSE: Nb, Ta, P, Ti) and weak negative Eu anomalies, indicating an island arc granite affinity. Combined with regional geological evidence, these rocks formed through crust-mantle interaction during the post-orogenic extensional stage. The Mailong gold deposit, primarily hosted in the granodiorite, is likely associated with tectonic-magmatic activities during the post-orogenic extension of the Paleo-Tethys evolution. This study provides critical age constraints and geochemical insights into the tectonic evolution and gold mineralization in the EKOB, offering valuable guidance for regional mineral exploration.
To reveal the tectonic evolution of the Proto-Tethys and Paleo-Tethys Oceans and their genetic links to gold-polymetallic mineralization in the East Kunlun orogenic belt (EKOB), this study conducted petrographic, geochemical, and LA-ICP-MS zircon U-Pb geochronological analyses on monzogranite and granodiorite from the Mailong gold deposit. The results show that the monzogranite and granodiorite crystallized at 421±11 Ma (Late Silurian) and 228±4 Ma (Late Triassic), respectively, exhibiting metaluminous, high-potassium calc-alkaline characteristics. Trace element analyses reveal enrichment in light rare earth elements (LREE), large-ion lithophile elements (LILE: Rb, K), and incompatible elements (U, Th, Pb), with depletion in high-field-strength elements (HFSE: Nb, Ta, P, Ti) and weak negative Eu anomalies, indicating an island arc granite affinity. Combined with regional geological evidence, these rocks formed through crust-mantle interaction during the post-orogenic extensional stage. The Mailong gold deposit, primarily hosted in the granodiorite, is likely associated with tectonic-magmatic activities during the post-orogenic extension of the Paleo-Tethys evolution. This study provides critical age constraints and geochemical insights into the tectonic evolution and gold mineralization in the EKOB, offering valuable guidance for regional mineral exploration.
2025, 50(6): 2124-2143.
doi: 10.3799/dqkx.2025.051
Abstract:
To further study the evolution process of the Songnan Low Uplift granite buried hill, the basement monzogranite in well Y8-A are analysed by chronology, major and trace, Sr-Nd-Pb-Hf isotopes, apatite fission track, and zircon (U-Th)/He methods. LA-ICP-MS zircon U-Pb dating is 235.6±4.8 Ma. The mafic dikes 40Ar/39Ar flateau age is 141.57±0.63 Ma. These granites belong to high potassium calc alkaline and peraluminous S-type granite. Their (87Sr/86Sr)i, εNd(t), and εHf(t) values are 0.707 93-0.709 44, -4.45 to -6.39, and --5.6 to 1.5, respectively. The apatite fission track age is 66.3±5.6 Ma, and the single zircon (U-Th) /He particle age ranges from (82.05±1.99) to (45.93±1.14) Ma. The comprehensive study shows that the monzogranite was formed in the post-collision background after the collision between Indochina and South China. The thermal history inversion results show that the evolution of granite buried hill can be divided into five stages: emplacement, slow cooling, fast cooling, near-surface denudation and sediments burial.
To further study the evolution process of the Songnan Low Uplift granite buried hill, the basement monzogranite in well Y8-A are analysed by chronology, major and trace, Sr-Nd-Pb-Hf isotopes, apatite fission track, and zircon (U-Th)/He methods. LA-ICP-MS zircon U-Pb dating is 235.6±4.8 Ma. The mafic dikes 40Ar/39Ar flateau age is 141.57±0.63 Ma. These granites belong to high potassium calc alkaline and peraluminous S-type granite. Their (87Sr/86Sr)i, εNd(t), and εHf(t) values are 0.707 93-0.709 44, -4.45 to -6.39, and --5.6 to 1.5, respectively. The apatite fission track age is 66.3±5.6 Ma, and the single zircon (U-Th) /He particle age ranges from (82.05±1.99) to (45.93±1.14) Ma. The comprehensive study shows that the monzogranite was formed in the post-collision background after the collision between Indochina and South China. The thermal history inversion results show that the evolution of granite buried hill can be divided into five stages: emplacement, slow cooling, fast cooling, near-surface denudation and sediments burial.
2025, 50(6): 2144-2162.
doi: 10.3799/dqkx.2024.112
Abstract:
Thailand is located in the core region of the East Paleotethyan Domain, preserves numerous tectonic-magmatic belts related to the subduction-collision-closure evolution of the Paleotethyan Ocean. However, the study on the Early-Middle Mesozoic volcanic rocks in the Loei zone remains unclear and the related petrogenesis and tectonic setting have not been constrained. Therefore, this study carries out detailed petrographic, zircon U-Pb geochronology, geochemistry and Sr-Nd-Hf isotopic studies on the Late Triassic volcanic rocks along the Loei zone in southeastern Thailand. Our study along with regional comparisins comprehensively analyze the Late Triassic magmatism and geodynamics process in the East Paleotethyan Domain. The study samples include basalts, rhyolites and dacites, with Late Triassic zircon U-Pb ages of 204-200 Ma. The basalts exhibit characteristics of Nb-enriched basalts, with (87Sr/86Sr)i=0.703 98-0.704 00, εNd(t)=+5.0 - +5.3, εHf(t)=+0.3 - +15.5. The felsic volcanic samples exhibit A-type characteristics and share similar isotopic compositions with the basalt samples, with (87Sr/86Sr)i = 0.702 71-0.704 72, εNd(t)=+4.0 - +4.2, εHf(t)=+6.8 - +16.0. Geochemical characteristics indicate that these basalts originated from a depleted OIB-like asthenospheric mantle source, while the felsic volcanic rocks possibly originated from the low level partial melting of these newly underplated mafic rocks. Regional comparisons indicate that these Late Triassic volcanic rocks were formed in a post-collisional extensional setting, representing the latest magmatism after the collision and closure of the East Paleotethyan Ocean. Comparison of chronological data shows that the Loei zone and the Chiang Khong-Lampang-Tak zones share similar Triassic age-spectra pattern, confirming that the Loei zone also recorded the collisional and post-collisional magmatism related to the Eastern Paleotethyan evolution during the Middle-Late Triassic.
Thailand is located in the core region of the East Paleotethyan Domain, preserves numerous tectonic-magmatic belts related to the subduction-collision-closure evolution of the Paleotethyan Ocean. However, the study on the Early-Middle Mesozoic volcanic rocks in the Loei zone remains unclear and the related petrogenesis and tectonic setting have not been constrained. Therefore, this study carries out detailed petrographic, zircon U-Pb geochronology, geochemistry and Sr-Nd-Hf isotopic studies on the Late Triassic volcanic rocks along the Loei zone in southeastern Thailand. Our study along with regional comparisins comprehensively analyze the Late Triassic magmatism and geodynamics process in the East Paleotethyan Domain. The study samples include basalts, rhyolites and dacites, with Late Triassic zircon U-Pb ages of 204-200 Ma. The basalts exhibit characteristics of Nb-enriched basalts, with (87Sr/86Sr)i=0.703 98-0.704 00, εNd(t)=+5.0 - +5.3, εHf(t)=+0.3 - +15.5. The felsic volcanic samples exhibit A-type characteristics and share similar isotopic compositions with the basalt samples, with (87Sr/86Sr)i = 0.702 71-0.704 72, εNd(t)=+4.0 - +4.2, εHf(t)=+6.8 - +16.0. Geochemical characteristics indicate that these basalts originated from a depleted OIB-like asthenospheric mantle source, while the felsic volcanic rocks possibly originated from the low level partial melting of these newly underplated mafic rocks. Regional comparisons indicate that these Late Triassic volcanic rocks were formed in a post-collisional extensional setting, representing the latest magmatism after the collision and closure of the East Paleotethyan Ocean. Comparison of chronological data shows that the Loei zone and the Chiang Khong-Lampang-Tak zones share similar Triassic age-spectra pattern, confirming that the Loei zone also recorded the collisional and post-collisional magmatism related to the Eastern Paleotethyan evolution during the Middle-Late Triassic.
2025, 50(6): 2163-2178.
doi: 10.3799/dqkx.2021.177
Abstract:
The geochemical properties and phase types of marine oil and gas in Tarim basin are complex and diverse. Heavy oil, normal oil, condensate and natural gas coexist from a reservoir profile. By comprehensively applying various geochemical analysis methods, the information of phase types, components and stable isotopes of deep-seated Marine oil and gas in Tarim basin is obtained, and the geochemical characteristics of different phase types of oil and gas are compared, and demonstrate a variety of secondary geochemical mechanisms and processes such as biodegradation, gas invasion and fractionation, thermochemical sulfate reduction (TSR), and thermal cracking of marine oil and gas; And further the quantitative evaluation parameters formulae for the strength of secondary transformation based on the products of secondary geochemistry such as thiadiamondoids and ethanodiamondoids were established respectively, can be effectively used in the qualitative prediction of the spatial distribution of oil and gas properties and phase behavior, the diversity of deep oil and gas phase formation mechanism and distribution of prediction before drilling and has certain theory and guiding significance.
The geochemical properties and phase types of marine oil and gas in Tarim basin are complex and diverse. Heavy oil, normal oil, condensate and natural gas coexist from a reservoir profile. By comprehensively applying various geochemical analysis methods, the information of phase types, components and stable isotopes of deep-seated Marine oil and gas in Tarim basin is obtained, and the geochemical characteristics of different phase types of oil and gas are compared, and demonstrate a variety of secondary geochemical mechanisms and processes such as biodegradation, gas invasion and fractionation, thermochemical sulfate reduction (TSR), and thermal cracking of marine oil and gas; And further the quantitative evaluation parameters formulae for the strength of secondary transformation based on the products of secondary geochemistry such as thiadiamondoids and ethanodiamondoids were established respectively, can be effectively used in the qualitative prediction of the spatial distribution of oil and gas properties and phase behavior, the diversity of deep oil and gas phase formation mechanism and distribution of prediction before drilling and has certain theory and guiding significance.
2025, 50(6): 2179-2198.
doi: 10.3799/dqkx.2025.020
Abstract:
The Sichuan basin is rich in oil and gas resources, and many years of exploration and development have accumulated a large amount of gas composition information, which provides good basic conditions for helium research. Helium content associated with natural gas from multiple strata and regions varies significantly. However, the relationship between hydrocarbons and associated helium is unclear. Based on the statistics of natural gas components obtained from oil and gas exploration in the Sichuan basin, it innovatively uses cluster analysis method to conduct Q-type cluster research on the He content and the content of associated gases CH4, N2, and CO2 in natural gas. The study analyzes the content of various types of helium, geological background, distribution pattern, and migration characteristics, then discusses the exploration and development strategies for helium resources. The main findings are as follows. (1) The helium associated with hydrocarbons in the Sichuan basin can be mainly divided into three types, Type Ⅰ is characterized by low He, low N2, low CO2 and high CH4 hydrocarbon gas reservoirs, Type Ⅱ is characterized by He-rich, high N2, medium CO2, medium CH4 hydrocarbon gas reservoirs, and Type Ⅲ is characterized by low He, low N2, high CO2 and low CH4 hydrocarbon gas reservoirs. (2) Gas components of type Ⅰ are shown as single peaks, with an average He content of 0.033 9% and a poor correlation with the N2 content. Non-hydrocarbon components of type Ⅱ gases show a multiple-peak distribution, with a high He content (average of 0.158%) and a strong positive correlation with the N2 content (r=0.837, P < 0.01), the CO2 content (r=0.662, P < 0.01), respectively. (3) Helium reservoirs of type Ⅰ are composited of shale gas reservoirs and overpressured gas reservoirs from in situ fracking of paleo-oil reservoirs. Low level of exotict helium and dilution from high-intensity gas generation are both responsible for the low helium content in type Ⅰ gases. Helium-rich reservoirs of type Ⅱ are recharged with water-soluble helium and nitrogen during hydrocarbon migration. (4) Natural gas or shale gas with abnormally high pressures, heavy hydrocarbon gas, as well as gas with high hydrogen sulfide content, are not favorable for helium accumulation. Successional anticline traps on long-distance flow paths of strata water, and the ancient resevoirs with multiple periods of interaction with stratum fluids, are the targets for helium exploration. The method of cluster analysis established for hydrocarbon-associated helium components can provide new ideas to study the geological characteristics of helium before obtaining a large amount of gas component information.
The Sichuan basin is rich in oil and gas resources, and many years of exploration and development have accumulated a large amount of gas composition information, which provides good basic conditions for helium research. Helium content associated with natural gas from multiple strata and regions varies significantly. However, the relationship between hydrocarbons and associated helium is unclear. Based on the statistics of natural gas components obtained from oil and gas exploration in the Sichuan basin, it innovatively uses cluster analysis method to conduct Q-type cluster research on the He content and the content of associated gases CH4, N2, and CO2 in natural gas. The study analyzes the content of various types of helium, geological background, distribution pattern, and migration characteristics, then discusses the exploration and development strategies for helium resources. The main findings are as follows. (1) The helium associated with hydrocarbons in the Sichuan basin can be mainly divided into three types, Type Ⅰ is characterized by low He, low N2, low CO2 and high CH4 hydrocarbon gas reservoirs, Type Ⅱ is characterized by He-rich, high N2, medium CO2, medium CH4 hydrocarbon gas reservoirs, and Type Ⅲ is characterized by low He, low N2, high CO2 and low CH4 hydrocarbon gas reservoirs. (2) Gas components of type Ⅰ are shown as single peaks, with an average He content of 0.033 9% and a poor correlation with the N2 content. Non-hydrocarbon components of type Ⅱ gases show a multiple-peak distribution, with a high He content (average of 0.158%) and a strong positive correlation with the N2 content (r=0.837, P < 0.01), the CO2 content (r=0.662, P < 0.01), respectively. (3) Helium reservoirs of type Ⅰ are composited of shale gas reservoirs and overpressured gas reservoirs from in situ fracking of paleo-oil reservoirs. Low level of exotict helium and dilution from high-intensity gas generation are both responsible for the low helium content in type Ⅰ gases. Helium-rich reservoirs of type Ⅱ are recharged with water-soluble helium and nitrogen during hydrocarbon migration. (4) Natural gas or shale gas with abnormally high pressures, heavy hydrocarbon gas, as well as gas with high hydrogen sulfide content, are not favorable for helium accumulation. Successional anticline traps on long-distance flow paths of strata water, and the ancient resevoirs with multiple periods of interaction with stratum fluids, are the targets for helium exploration. The method of cluster analysis established for hydrocarbon-associated helium components can provide new ideas to study the geological characteristics of helium before obtaining a large amount of gas component information.
2025, 50(6): 2199-2208.
doi: 10.3799/dqkx.2025.026
Abstract:
The Shahejie Formation shale in Dongying sag is one of the key formations in shale oil exploration and development. However, its complex mineral composition and diverse laminae types result in strong heterogeneity in the distribution of favorable shale oil zones, posing significant challenges for prediction and leading to highly variable development outcomes. In this study it focuses on the organic-rich lacustrine shale of the lower third member of the Shahejie Formation (Sha-3 lower member) as a case study. By employing techniques such as core observation, thin section analysis, mineral composition testing, stepwise pyrolysis, low-temperature nitrogen adsorption, and field emission scanning electron microscopy (FE-SEM), the study characterizes variations in reservoir quality and oil-bearing potential among different shale types. The analysis clarifies the pore size distribution for shale oil occurrence and identifies the lower pore size limit for movable oil, while exploring factors influencing shale oil content. The Shahejie Formation shale features diverse pore types, including laminar fractures and various intergranular pores. Under ambient temperature and pressure, residual shale oil is mainly stored in the pores of 15-100 nm in the nanoscale range, with a lower pore size limit of approximately 3 nm for free oil occurrence. Organic matter abundance (TOC) provides the material foundation for shale oil generation and enrichment, while sufficiently large reservoir spaces ensure the retention of significant hydrocarbon quantities. Among the studied shale lithofacies, organic-rich laminated calcareous shale and laminated mixed shale with high TOC content and high porosity demonstrate superior oil-bearing potential and higher free oil content, making them the most favorable lithofacies in the study area. These findings offer critical insights for advancing the understanding of lacustrine shale oil enrichment mechanisms and optimizing development strategies.
The Shahejie Formation shale in Dongying sag is one of the key formations in shale oil exploration and development. However, its complex mineral composition and diverse laminae types result in strong heterogeneity in the distribution of favorable shale oil zones, posing significant challenges for prediction and leading to highly variable development outcomes. In this study it focuses on the organic-rich lacustrine shale of the lower third member of the Shahejie Formation (Sha-3 lower member) as a case study. By employing techniques such as core observation, thin section analysis, mineral composition testing, stepwise pyrolysis, low-temperature nitrogen adsorption, and field emission scanning electron microscopy (FE-SEM), the study characterizes variations in reservoir quality and oil-bearing potential among different shale types. The analysis clarifies the pore size distribution for shale oil occurrence and identifies the lower pore size limit for movable oil, while exploring factors influencing shale oil content. The Shahejie Formation shale features diverse pore types, including laminar fractures and various intergranular pores. Under ambient temperature and pressure, residual shale oil is mainly stored in the pores of 15-100 nm in the nanoscale range, with a lower pore size limit of approximately 3 nm for free oil occurrence. Organic matter abundance (TOC) provides the material foundation for shale oil generation and enrichment, while sufficiently large reservoir spaces ensure the retention of significant hydrocarbon quantities. Among the studied shale lithofacies, organic-rich laminated calcareous shale and laminated mixed shale with high TOC content and high porosity demonstrate superior oil-bearing potential and higher free oil content, making them the most favorable lithofacies in the study area. These findings offer critical insights for advancing the understanding of lacustrine shale oil enrichment mechanisms and optimizing development strategies.
2025, 50(6): 2209-2226.
doi: 10.3799/dqkx.2024.143
Abstract:
To examine the fine-grained gravity flow sedimentation of the Chang 73 submember in the Longdong area, Ordos basin, through observation of core and thin sections, XRD analysis, and trace elements analysis, the sedimentary characteristics and influencing factors of fine-grained gravity flow sedimentation were studied. 7 lithofacies assemblages were formed due to different depositional processes: the shale with lamina tuffaceous assemblage, the fine-grained turbidity currents to mud flow assemblage, the transitional flow to mud flow assemblage, the slump to debris flow to mud flow assemblage, the surge-like turbidity flow assemblage, the quasi-steady turbidity current assemblage, and the concentrated density flow assemblage. The development of fine-grained gravity flow is mostly controlled by tectonic activities, paleo-climate change, and paleo-topography of the lacustrine basin. Tectonic activities are the key factors in inducing the development of slump-triggered fine-grained gravity flow sedimentation, while flood events promote the development of flood-triggered fine-grained gravity flow sedimentation. The characteristics of the paleogeomorphology have a significant control effect on the distribution of fine-grained gravity flow sedimentation, the gradient of the slope significantly influences the depositional characteristics of slump-triggered fine-grained gravity flows.
To examine the fine-grained gravity flow sedimentation of the Chang 73 submember in the Longdong area, Ordos basin, through observation of core and thin sections, XRD analysis, and trace elements analysis, the sedimentary characteristics and influencing factors of fine-grained gravity flow sedimentation were studied. 7 lithofacies assemblages were formed due to different depositional processes: the shale with lamina tuffaceous assemblage, the fine-grained turbidity currents to mud flow assemblage, the transitional flow to mud flow assemblage, the slump to debris flow to mud flow assemblage, the surge-like turbidity flow assemblage, the quasi-steady turbidity current assemblage, and the concentrated density flow assemblage. The development of fine-grained gravity flow is mostly controlled by tectonic activities, paleo-climate change, and paleo-topography of the lacustrine basin. Tectonic activities are the key factors in inducing the development of slump-triggered fine-grained gravity flow sedimentation, while flood events promote the development of flood-triggered fine-grained gravity flow sedimentation. The characteristics of the paleogeomorphology have a significant control effect on the distribution of fine-grained gravity flow sedimentation, the gradient of the slope significantly influences the depositional characteristics of slump-triggered fine-grained gravity flows.
2025, 50(6): 2227-2238.
doi: 10.3799/dqkx.2025.017
Abstract:
The Xixiangchi Formation is a potential target for oil and gas exploration in the Sichuan basin, yet detailed descriptions of its reservoir space diagenetic mineral filling characteristics and hydrocarbon charging features are scarce. Based on 24 core samples, in this study it dissects the reservoir spaces and hydrocarbon charging characteristics of the Cambrian Xixiangchi Formation in the central area of the Sichuan basin through detailed thin-section microscopic observations, cathodoluminescence testing, microscopic hydrocarbon trace detection, and systematic fluid inclusion analysis. The results indicate that the Xixiangchi Formation primarily comprises dissolution pores (vugs), interparticle (intercrystalline) pores, and fractures as its reservoir spaces, which are filled with multiple types and stages of diagenetic minerals such as dolomite, calcite, and quartz, as well as bitumen. Microscopic traces such as bitumen filled in reservoir spaces, bitumen or bitumen-bearing inclusions and natural gas inclusions trapped in diagenetic minerals record multiple stages of hydrocarbon activities and the process of adjustment and modification. The overall hydrocarbon charging characteristics show that ancient oil reservoirs were formed in the early Indosinian period (Early Triassic). Large-scale oil cracking into gas occurred from the late Indosinian to early Yanshanian periods (Late Triassic to Early-Middle Jurassic), forming the first stage of natural gas charging. Residual oil cracking into gas occurred in the middle Yanshanian period (Late Jurassic to Early Cretaceous), forming the second stage of natural gas charging. Adjustment and modification took place in the late Yanshanian period (Middle-Late Cretaceous), forming the third stage of natural gas charging.
The Xixiangchi Formation is a potential target for oil and gas exploration in the Sichuan basin, yet detailed descriptions of its reservoir space diagenetic mineral filling characteristics and hydrocarbon charging features are scarce. Based on 24 core samples, in this study it dissects the reservoir spaces and hydrocarbon charging characteristics of the Cambrian Xixiangchi Formation in the central area of the Sichuan basin through detailed thin-section microscopic observations, cathodoluminescence testing, microscopic hydrocarbon trace detection, and systematic fluid inclusion analysis. The results indicate that the Xixiangchi Formation primarily comprises dissolution pores (vugs), interparticle (intercrystalline) pores, and fractures as its reservoir spaces, which are filled with multiple types and stages of diagenetic minerals such as dolomite, calcite, and quartz, as well as bitumen. Microscopic traces such as bitumen filled in reservoir spaces, bitumen or bitumen-bearing inclusions and natural gas inclusions trapped in diagenetic minerals record multiple stages of hydrocarbon activities and the process of adjustment and modification. The overall hydrocarbon charging characteristics show that ancient oil reservoirs were formed in the early Indosinian period (Early Triassic). Large-scale oil cracking into gas occurred from the late Indosinian to early Yanshanian periods (Late Triassic to Early-Middle Jurassic), forming the first stage of natural gas charging. Residual oil cracking into gas occurred in the middle Yanshanian period (Late Jurassic to Early Cretaceous), forming the second stage of natural gas charging. Adjustment and modification took place in the late Yanshanian period (Middle-Late Cretaceous), forming the third stage of natural gas charging.
2025, 50(6): 2239-2254.
doi: 10.3799/dqkx.2025.054
Abstract:
The deep-margin carbonate rocks in the Tarim basin exhibit dense physical properties and are prone to brittle deformation under stress concentration, resulting in the development of multi-order strike-slip fault systems. However, due to the characteristics of low-order faults being 'small in scale, weak in activity, and diverse in direction', their distribution and genesis have been argumentative in current structural research. Based on the high-quality 3D seismic data of the Shunbei area, it built the geophysical identification methods and distribution prediction of low-order faults. Through the systematic analysis of seismic, drilling, logging and field survey data, the distribution patterns, genesis models, and characteristics of reservoir formation of low-order faults in the Shunbei area were revealed. Preliminary suggestions for exploration evaluation and deployment strategies were proposed.(1) A technical sequence for identifying low-order faults was developed, which involves 'enhanced geophysical preprocessing first, followed by optimal attribute selection of sub-regions'. This results in improving the identification accuracy of low-order faults to 1 km in length. (2) Five sets of NE, NEE, NW, near NS, and near EW trending low-order faults in the northeastern central Shunbei area were recognised, and classified into three genetic types: nearly parallel system, acute angle system, and near vertical system. (3) Low-order faults typically do not develop a complete fault core-damage zone architecture, but consist of multiple sets of fracture zones, lacking large angular gravel breccia zones and angular gravel cavities. It is smaller in scale and weaker with connectivity compared to main strike-slip faults, making them preferred for forming overpressured oil and gas reservoir systems. Identifying target reservoirs with a certain scale is crucial for the decision of the low-order faults exploration, requiring consideration of geology-engineering integration, preferentially selecting beads-shaped reflections in high-density areas of low-order faults and designing Multi-Target Well.
The deep-margin carbonate rocks in the Tarim basin exhibit dense physical properties and are prone to brittle deformation under stress concentration, resulting in the development of multi-order strike-slip fault systems. However, due to the characteristics of low-order faults being 'small in scale, weak in activity, and diverse in direction', their distribution and genesis have been argumentative in current structural research. Based on the high-quality 3D seismic data of the Shunbei area, it built the geophysical identification methods and distribution prediction of low-order faults. Through the systematic analysis of seismic, drilling, logging and field survey data, the distribution patterns, genesis models, and characteristics of reservoir formation of low-order faults in the Shunbei area were revealed. Preliminary suggestions for exploration evaluation and deployment strategies were proposed.(1) A technical sequence for identifying low-order faults was developed, which involves 'enhanced geophysical preprocessing first, followed by optimal attribute selection of sub-regions'. This results in improving the identification accuracy of low-order faults to 1 km in length. (2) Five sets of NE, NEE, NW, near NS, and near EW trending low-order faults in the northeastern central Shunbei area were recognised, and classified into three genetic types: nearly parallel system, acute angle system, and near vertical system. (3) Low-order faults typically do not develop a complete fault core-damage zone architecture, but consist of multiple sets of fracture zones, lacking large angular gravel breccia zones and angular gravel cavities. It is smaller in scale and weaker with connectivity compared to main strike-slip faults, making them preferred for forming overpressured oil and gas reservoir systems. Identifying target reservoirs with a certain scale is crucial for the decision of the low-order faults exploration, requiring consideration of geology-engineering integration, preferentially selecting beads-shaped reflections in high-density areas of low-order faults and designing Multi-Target Well.
2025, 50(6): 2255-2269.
doi: 10.3799/dqkx.2024.110
Abstract:
Current evaluation indicators for depicting the expected effectiveness of exploration program often fail to reflect physical process, and the involved parameters are difficult to determine. Besides, the exploration layout strategies in existing optimization frameworks usually rely on the positional relationship, and require determination of the investigation range in advance. To solve the above problems, taking the undrained shear strength parameter as an example, in this paper it proposes and employs the expected reduction rate of the root mean square error (ERRS) to quantify the expected degree of improvement in the concentration effect of factor of safety assessment results towards the reference factor of safety due to the incorporation of reference exploration data, which serves as an indicator to evaluate the expected effectiveness of exploration program. Additionally, a framework for optimizing exploration program is constructed using this indicator in conjunction with a greedy algorithm, aimed at optimizing the locations and number of exploration points. The ERRS indicator calculation process employs the Cholesky decomposition-based midpoint method and the improved Bayesian updating method to discretize both unconditional and conditional random fields. The multiple second-order response surface is used as a surrogate model to replace the deterministic slope stability analysis of spatially variable slopes, significantly enhancing the precision and efficiency of the indicator calculation. Example of undrained saturated clay slope shows: the proposed ERRS indicator can achieve evaluation results close to other indicators without the need to determine complex parameters; the constructed exploration program optimization framework can provide an improved arrangement of exploration points under a specified number of explorations, resulting in more cost-effective and better-performing exploration program without the need to predefine the exploration range. The proposed indicator and optimization framework can serve as a reference for evaluating and optimally designing exploration program in practical slope engineering projects.
Current evaluation indicators for depicting the expected effectiveness of exploration program often fail to reflect physical process, and the involved parameters are difficult to determine. Besides, the exploration layout strategies in existing optimization frameworks usually rely on the positional relationship, and require determination of the investigation range in advance. To solve the above problems, taking the undrained shear strength parameter as an example, in this paper it proposes and employs the expected reduction rate of the root mean square error (ERRS) to quantify the expected degree of improvement in the concentration effect of factor of safety assessment results towards the reference factor of safety due to the incorporation of reference exploration data, which serves as an indicator to evaluate the expected effectiveness of exploration program. Additionally, a framework for optimizing exploration program is constructed using this indicator in conjunction with a greedy algorithm, aimed at optimizing the locations and number of exploration points. The ERRS indicator calculation process employs the Cholesky decomposition-based midpoint method and the improved Bayesian updating method to discretize both unconditional and conditional random fields. The multiple second-order response surface is used as a surrogate model to replace the deterministic slope stability analysis of spatially variable slopes, significantly enhancing the precision and efficiency of the indicator calculation. Example of undrained saturated clay slope shows: the proposed ERRS indicator can achieve evaluation results close to other indicators without the need to determine complex parameters; the constructed exploration program optimization framework can provide an improved arrangement of exploration points under a specified number of explorations, resulting in more cost-effective and better-performing exploration program without the need to predefine the exploration range. The proposed indicator and optimization framework can serve as a reference for evaluating and optimally designing exploration program in practical slope engineering projects.
2025, 50(6): 2270-2283.
doi: 10.3799/dqkx.2024.114
Abstract:
Utilizing AI technology for landslide susceptibility mapping offers the advantages of efficiency and accuracy.To promote its application in landslide disaster prevention and control, in this article it introduces and summarizes the principles and characteristics of machine learning, deep learning, and ensemble learning models. Representative models such as Support Vector Machines, Deep Random Forests, and Random Forests were applied for analysis in Lueyang County, Shaanxi Province. It discusses the application and development directions of AI technology in the field of landslide susceptibility. The results indicate that ensemble learning models based on decision trees, compared to logistic regression and support vector machines, demonstrate higher efficacy with AUC values above 0.90. Under the commonly used class imbalance sampling strategy in LSM (landslide susceptibility mapping), ensemble models based on Boosting show advantages and are relatively less affected by sampling ratios. Generative Adversarial Networks can enhance the performance of deep learning models under data constraints, where in this study, the AUC value increased from 0.77 to 0.82. Combining landslide theoretical models with AI data models has great potential; leveraging AI models that fully utilize time-series data can improve model performance and help reveal the chain disaster effects and spatio-temporal evolution characteristics of landslides; conducting systematic studies of various learning models is of significant importance for the application of AI technology in landslide susceptibility mapping.
Utilizing AI technology for landslide susceptibility mapping offers the advantages of efficiency and accuracy.To promote its application in landslide disaster prevention and control, in this article it introduces and summarizes the principles and characteristics of machine learning, deep learning, and ensemble learning models. Representative models such as Support Vector Machines, Deep Random Forests, and Random Forests were applied for analysis in Lueyang County, Shaanxi Province. It discusses the application and development directions of AI technology in the field of landslide susceptibility. The results indicate that ensemble learning models based on decision trees, compared to logistic regression and support vector machines, demonstrate higher efficacy with AUC values above 0.90. Under the commonly used class imbalance sampling strategy in LSM (landslide susceptibility mapping), ensemble models based on Boosting show advantages and are relatively less affected by sampling ratios. Generative Adversarial Networks can enhance the performance of deep learning models under data constraints, where in this study, the AUC value increased from 0.77 to 0.82. Combining landslide theoretical models with AI data models has great potential; leveraging AI models that fully utilize time-series data can improve model performance and help reveal the chain disaster effects and spatio-temporal evolution characteristics of landslides; conducting systematic studies of various learning models is of significant importance for the application of AI technology in landslide susceptibility mapping.
2025, 50(6): 2284-2297.
doi: 10.3799/dqkx.2024.141
Abstract:
Natural climate makes rammed earth sites develop weathering disease, threatening its stable preservation. In this paper it summarizes the types of weathering diseases of sites, expounds the research progress of the evolution law and mechanism of the diseases, and analyzes the protection and reinforcement methods and applicability. The weathering of the site is affected by physical, chemical and biological processes. The mechanical strength and surface hardness decrease with the weathering process, and the thermal physical parameters of the topsoil and the internal rammed soil are significantly different. The coupling of water, temperature, wind and salt makes the surface of the site tend to form a crust-loose layer, and its pores are double-porosity structure, which makes the water retention mode be different from that of the inner rammed soil. Under the action of the environment, the loose layer produces stress fatigue before the crust, and the crust peeling occurs. All the common protection and reinforcement methods except microbial induced calcite precipitation (MICP) have been applied in engineering. The rammed earth site has been in the unsaturated state for a long time, and most of the existing results focus on the saturated state, which cannot accurately describe the evolution of the hydraulic and mechanical behavior and the pathogenic mechanism of the actual working condition, so it is urgent to further study.
Natural climate makes rammed earth sites develop weathering disease, threatening its stable preservation. In this paper it summarizes the types of weathering diseases of sites, expounds the research progress of the evolution law and mechanism of the diseases, and analyzes the protection and reinforcement methods and applicability. The weathering of the site is affected by physical, chemical and biological processes. The mechanical strength and surface hardness decrease with the weathering process, and the thermal physical parameters of the topsoil and the internal rammed soil are significantly different. The coupling of water, temperature, wind and salt makes the surface of the site tend to form a crust-loose layer, and its pores are double-porosity structure, which makes the water retention mode be different from that of the inner rammed soil. Under the action of the environment, the loose layer produces stress fatigue before the crust, and the crust peeling occurs. All the common protection and reinforcement methods except microbial induced calcite precipitation (MICP) have been applied in engineering. The rammed earth site has been in the unsaturated state for a long time, and most of the existing results focus on the saturated state, which cannot accurately describe the evolution of the hydraulic and mechanical behavior and the pathogenic mechanism of the actual working condition, so it is urgent to further study.
2025, 50(6): 2298-2310.
doi: 10.3799/dqkx.2024.052
Abstract:
The Tianxingzhou carbonate rock belt in Wuhan has developed an exceptionally thick sandstone dolomite formation. To elucidate the genesis and engineering characteristics of this rock formation, a comprehensive study was undertaken employing various methods, including structural surveys, thin section analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), particle analysis, and saturated uniaxial compressive strength tests. The results indicate that the study area is situated between three faults, and the strata are inverted, suggesting that the region experienced intense compressive stress during the Indosinian period and tensile stress during the Yanshan period. Regional structural features and microscopic observations corroborate this interpretation. Notably, the higher the degree of sandstone, the lower the dolomite mineral content, and the higher the quartz and clay mineral content. The migration and evolution characteristics of major chemical components, such as CaO and MgO, exhibit a negative correlation with the dolomite sandstone process, while components like SiO2, Al2O3 and Fe2O3 display a positive correlation. In summary, the primary causes of the dolomite sandstone and its heterogeneous characteristics in the study area can be attributed to three distinct scales: "macroscopic structural dynamics", "microscopic mineral structure composition", and "microscopic chemical composition evolution". The degree of sandstone significantly influences the saturated uniaxialcompressive strength of dolomite. The reduction amplitudes for the "micro-weak", "micro-medium", and "micro-strong" sandstone stages can reach 38.6%, 68.1%, and 90.0%, respectively, exhibiting a power function relationship. Consequently, the standard value of the saturated uniaxial compressive strength for the fully sandstone and extremely broken dolomite in ⑤1 layer was fitted to be 1.3 MPa, resolving the engineering challenge of obtaining rock mechanics parameters for fully sandstone dolomite through indoor testing of standard rock samples.
The Tianxingzhou carbonate rock belt in Wuhan has developed an exceptionally thick sandstone dolomite formation. To elucidate the genesis and engineering characteristics of this rock formation, a comprehensive study was undertaken employing various methods, including structural surveys, thin section analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), particle analysis, and saturated uniaxial compressive strength tests. The results indicate that the study area is situated between three faults, and the strata are inverted, suggesting that the region experienced intense compressive stress during the Indosinian period and tensile stress during the Yanshan period. Regional structural features and microscopic observations corroborate this interpretation. Notably, the higher the degree of sandstone, the lower the dolomite mineral content, and the higher the quartz and clay mineral content. The migration and evolution characteristics of major chemical components, such as CaO and MgO, exhibit a negative correlation with the dolomite sandstone process, while components like SiO2, Al2O3 and Fe2O3 display a positive correlation. In summary, the primary causes of the dolomite sandstone and its heterogeneous characteristics in the study area can be attributed to three distinct scales: "macroscopic structural dynamics", "microscopic mineral structure composition", and "microscopic chemical composition evolution". The degree of sandstone significantly influences the saturated uniaxialcompressive strength of dolomite. The reduction amplitudes for the "micro-weak", "micro-medium", and "micro-strong" sandstone stages can reach 38.6%, 68.1%, and 90.0%, respectively, exhibiting a power function relationship. Consequently, the standard value of the saturated uniaxial compressive strength for the fully sandstone and extremely broken dolomite in ⑤1 layer was fitted to be 1.3 MPa, resolving the engineering challenge of obtaining rock mechanics parameters for fully sandstone dolomite through indoor testing of standard rock samples.
2025, 50(6): 2311-2329.
doi: 10.3799/dqkx.2025.008
Abstract:
In order to comprehensively consider the differences between different types of landslides, improve the accuracy and engineering application value of landslide susceptibility prediction, taking Wanzhou District, Chongqing City as an example, support vector machine, C5.0 decision tree, logistic regression, and multilayer perceptron models were applied to model the susceptibility of a single stacked layer landslide and rockfall. Based on the optimal comprehensive performance model, direct coupling method, probability statistics method, and susceptibility comparison method were used to couple and model different types of landslides, and their uncertainties were evaluated. The results show that the C5.0 decision tree model performs best in susceptibility prediction for single-type landslides, with AUC values exceeding 0.930. The susceptibility prediction results of the three coupling methods are generally consistent with the actual situation, among which the comparative susceptibility method exhibits higher AUC values and accuracy in frequency ratio, demonstrating the best predictive performance. The probabilistic statistical method ranks second, followed by the direct coupling method. In terms of comprehensively reflecting the evolution patterns of landslides, adapting to actual scenarios, and supporting prevention and control decisions, considering the coupling of landslide types yields better landslide susceptibility predictions than considering only single-type landslides. However, it is still necessary to explore the specificity among different types of landslides and optimize coupling methods in greater depth in the future.
In order to comprehensively consider the differences between different types of landslides, improve the accuracy and engineering application value of landslide susceptibility prediction, taking Wanzhou District, Chongqing City as an example, support vector machine, C5.0 decision tree, logistic regression, and multilayer perceptron models were applied to model the susceptibility of a single stacked layer landslide and rockfall. Based on the optimal comprehensive performance model, direct coupling method, probability statistics method, and susceptibility comparison method were used to couple and model different types of landslides, and their uncertainties were evaluated. The results show that the C5.0 decision tree model performs best in susceptibility prediction for single-type landslides, with AUC values exceeding 0.930. The susceptibility prediction results of the three coupling methods are generally consistent with the actual situation, among which the comparative susceptibility method exhibits higher AUC values and accuracy in frequency ratio, demonstrating the best predictive performance. The probabilistic statistical method ranks second, followed by the direct coupling method. In terms of comprehensively reflecting the evolution patterns of landslides, adapting to actual scenarios, and supporting prevention and control decisions, considering the coupling of landslide types yields better landslide susceptibility predictions than considering only single-type landslides. However, it is still necessary to explore the specificity among different types of landslides and optimize coupling methods in greater depth in the future.
2025, 50(6): 2330-2341.
doi: 10.3799/dqkx.2024.109
Abstract:
To study the landslide response mechanism of accumulated landslide with line-like interface between sliding mass and bedrock under the coupling action of reservoir water and rainfall. Taking the Taping H1 landslide in Quchi County as an example, the characteristics of landslide movement and instability evolution mechanism are revealed through engineering geological survey and monitoring data analysis as well as combined with correlation theory and discrete element method. Taping H1 landslide has a stepped deformation mode, and the landslide deformation rate decreases with the rising of the elevation. Both reservoir water and rainfall are considered as governed external factors affecting landslide deformation, the seepage effect caused by the continuous drop of reservoir water resulting in obvious slope deformation at the front of the landslide, and during the fluctuation of reservoir water level, uninterrupted rainfall infiltration has a significant positive effect on the slope movement at the middle part of the landslide. Under the combined action of reservoir water and rainfall, the landslide instability will first occur at the surface rock mass at the toe, and then developed from the front of the landslide to the middle of the landslide, showing the landslide exhibited a multi-stage retrogression-type failure evolution. At present, the deformation at the front and middle parts of the Taping H1 landslide is continuous, and it is urgent to carry out landslide prevention and control projects to improve the landslide stability.
To study the landslide response mechanism of accumulated landslide with line-like interface between sliding mass and bedrock under the coupling action of reservoir water and rainfall. Taking the Taping H1 landslide in Quchi County as an example, the characteristics of landslide movement and instability evolution mechanism are revealed through engineering geological survey and monitoring data analysis as well as combined with correlation theory and discrete element method. Taping H1 landslide has a stepped deformation mode, and the landslide deformation rate decreases with the rising of the elevation. Both reservoir water and rainfall are considered as governed external factors affecting landslide deformation, the seepage effect caused by the continuous drop of reservoir water resulting in obvious slope deformation at the front of the landslide, and during the fluctuation of reservoir water level, uninterrupted rainfall infiltration has a significant positive effect on the slope movement at the middle part of the landslide. Under the combined action of reservoir water and rainfall, the landslide instability will first occur at the surface rock mass at the toe, and then developed from the front of the landslide to the middle of the landslide, showing the landslide exhibited a multi-stage retrogression-type failure evolution. At present, the deformation at the front and middle parts of the Taping H1 landslide is continuous, and it is urgent to carry out landslide prevention and control projects to improve the landslide stability.
2025, 50(6): 2342-2355.
doi: 10.3799/dqkx.2024.152
Abstract:
Twinning is one the micromechanisms of plastic deformation of marble. To investigate the twinning performance during faulting, shear ruptures with different deformations were induced in Hezhou marble. Microscopic observation and quantitative analysis were performed on twinning characteristics in cross sections perpendicular to faulting plane. The results show that the twinning in the faulting zone was obviously different from that outside of the zone, presenting the characteristics of localization, kinking, thickening, bifurcation and spiking out, which is largely controlled by the relation between the shear direction and twin plane dip. Twin density of the entire sample increased slightly after loading, while twin incidence fluctuated in high level. The average twin width was not affected by loading, however, the maximum twin width increased steadily up to three times with faulting deformation. The above results show that under low confining pressure, the twinning of Hezhou marble is unobvious overall, but concentrated in the shear zone, mainly manifested by the increase of the width of the twin. The apparent characteristics of twinning are controlled by the relative relationship between the shear direction and the inclination of the twin lamellae.
Twinning is one the micromechanisms of plastic deformation of marble. To investigate the twinning performance during faulting, shear ruptures with different deformations were induced in Hezhou marble. Microscopic observation and quantitative analysis were performed on twinning characteristics in cross sections perpendicular to faulting plane. The results show that the twinning in the faulting zone was obviously different from that outside of the zone, presenting the characteristics of localization, kinking, thickening, bifurcation and spiking out, which is largely controlled by the relation between the shear direction and twin plane dip. Twin density of the entire sample increased slightly after loading, while twin incidence fluctuated in high level. The average twin width was not affected by loading, however, the maximum twin width increased steadily up to three times with faulting deformation. The above results show that under low confining pressure, the twinning of Hezhou marble is unobvious overall, but concentrated in the shear zone, mainly manifested by the increase of the width of the twin. The apparent characteristics of twinning are controlled by the relative relationship between the shear direction and the inclination of the twin lamellae.
2025, 50(6): 2356-2371.
doi: 10.3799/dqkx.2022.469
Abstract:
Few studies pay attention to revealing the relationship between the amount of landslide material and the formation of gully debris flow, although a large number of shallow landslides in a watershed can lead to gully-type debris. Thus, the landslide source conditions required for the formation of this type of debris flow are evaluated based on the mechanism of debris flow formation. To analyze the relationship between the debris flow by shallow landslides in Baozhuang Village, Fujian, in 2010. And the material model of gully-type debris flow by shallow landslides was proposed. The result shows that the larger the landslides area in the catchment, the greater the possibility of gully-type debris flow. The landslide area (A0), catchment area (A) and soil thickness (h) can be applied to classify the susceptibility class of gully-type debris flow by shallow landslides. For the gullies in the East China region: when the average soil thickness of the catchment is h (m), the total of area where landslides occur (A0) is related to the area of the catchment (A) as: it is very high probabilities of debris flow formation when A0/A≥0.045×(3/h). The probabilities of debris flow formation is medium when 0.02×(3/h)≤A0/A≤0.045×(3/h). The probabilities of debris flow formation is very low when 0.02×(3/h)≥A0/A. When the total area of landslides entering the channel (AL) is related to the area of the catchment (A) as: it is very high probabilities of debris flow formation when AL/A≥0.03×(3/h). The probabilities of debris flow formation is medium when 0.006 5×(3/h)≤AL/A≤0.03×(3/h). The probabilities of debris flow formation is very low when 0.006 5×(3/h)≥AL/A. The empirical models are simple, and the data needed necessary for the input are easily measurable catchment areas and landslides area. The approach may be applied to the analysis debris flow by shallow landslides in other areas due to simplicity, when adapting the threshold parameters according to new local conditions.
Few studies pay attention to revealing the relationship between the amount of landslide material and the formation of gully debris flow, although a large number of shallow landslides in a watershed can lead to gully-type debris. Thus, the landslide source conditions required for the formation of this type of debris flow are evaluated based on the mechanism of debris flow formation. To analyze the relationship between the debris flow by shallow landslides in Baozhuang Village, Fujian, in 2010. And the material model of gully-type debris flow by shallow landslides was proposed. The result shows that the larger the landslides area in the catchment, the greater the possibility of gully-type debris flow. The landslide area (A0), catchment area (A) and soil thickness (h) can be applied to classify the susceptibility class of gully-type debris flow by shallow landslides. For the gullies in the East China region: when the average soil thickness of the catchment is h (m), the total of area where landslides occur (A0) is related to the area of the catchment (A) as: it is very high probabilities of debris flow formation when A0/A≥0.045×(3/h). The probabilities of debris flow formation is medium when 0.02×(3/h)≤A0/A≤0.045×(3/h). The probabilities of debris flow formation is very low when 0.02×(3/h)≥A0/A. When the total area of landslides entering the channel (AL) is related to the area of the catchment (A) as: it is very high probabilities of debris flow formation when AL/A≥0.03×(3/h). The probabilities of debris flow formation is medium when 0.006 5×(3/h)≤AL/A≤0.03×(3/h). The probabilities of debris flow formation is very low when 0.006 5×(3/h)≥AL/A. The empirical models are simple, and the data needed necessary for the input are easily measurable catchment areas and landslides area. The approach may be applied to the analysis debris flow by shallow landslides in other areas due to simplicity, when adapting the threshold parameters according to new local conditions.
2025, 50(6): 2372-2386.
doi: 10.3799/dqkx.2025.003
Abstract:
Similar material is the key to the model test of reservoir rock slope. A kind of solid-liquid two-phase similar material which can simulate physical and mechanical properties similar and seepage action similar of slope rock mass at the same time is developed through orthogonal test and a large number of laboratory tests. The material uses quartz sand, iron powder and barite powder as aggregate, cement and gypsum as cementing agent and silicone oil as regulator. The influence of material different ratios on its mechanical properties is systematically studied, and the main control components of each property are determined, and the empirical equation between each parameter and the ratio of materials is established by multiple regression analysis. Finally, the similar materials of model test are prepared in combination with an engineering case, and the similar effect of those materials is evaluated, and the materials are applied to the failure mode and seepage field analysis in the model test of reservoir slope. The test results show follows: (1) Physical, mechanical parameters, and hydro-physical properties of similar materials are widely distributed, which can meet the requirements of physical and mechanical properties similar and seepage action similar of rock slope model test, and it is an ideal solid-liquid two-phase similar material. (2) The main control components of similar materials are obvious, which is convenient to simulate different types of slope rock mass by adjusting the ratio. (3) Multiple regression analysis can efficiently concoct similar materials for slope model test, and the similarity effect is good. The slope model undergoes compression shear deformation and failure, and the variation law of pore water pressure during model testing under the action of reservoir water is analyzed. The research results can provide reference for further research on multi-field evolution characteristics of reservoir rock slope model test.
Similar material is the key to the model test of reservoir rock slope. A kind of solid-liquid two-phase similar material which can simulate physical and mechanical properties similar and seepage action similar of slope rock mass at the same time is developed through orthogonal test and a large number of laboratory tests. The material uses quartz sand, iron powder and barite powder as aggregate, cement and gypsum as cementing agent and silicone oil as regulator. The influence of material different ratios on its mechanical properties is systematically studied, and the main control components of each property are determined, and the empirical equation between each parameter and the ratio of materials is established by multiple regression analysis. Finally, the similar materials of model test are prepared in combination with an engineering case, and the similar effect of those materials is evaluated, and the materials are applied to the failure mode and seepage field analysis in the model test of reservoir slope. The test results show follows: (1) Physical, mechanical parameters, and hydro-physical properties of similar materials are widely distributed, which can meet the requirements of physical and mechanical properties similar and seepage action similar of rock slope model test, and it is an ideal solid-liquid two-phase similar material. (2) The main control components of similar materials are obvious, which is convenient to simulate different types of slope rock mass by adjusting the ratio. (3) Multiple regression analysis can efficiently concoct similar materials for slope model test, and the similarity effect is good. The slope model undergoes compression shear deformation and failure, and the variation law of pore water pressure during model testing under the action of reservoir water is analyzed. The research results can provide reference for further research on multi-field evolution characteristics of reservoir rock slope model test.
2025, 50(6): 2387-2399.
doi: 10.3799/dqkx.2024.309
Abstract:
When a shield tunnel passes under the main canal of the South-to-North Water Diversion Project, leakage at the bottom of the canal structure can lead to more severe hazards. Therefore, to study the disturbance deformation patterns under the coupling effects of bidirectional interactions, the FEFLOW software was used to simulate the influence range of groundwater seepage under different leakage conditions in the canal. The FLAC3D software was employed to establish a model of the canal-stratum-tunnel system, and numerical simulations of cooperative deformation under different construction conditions were conducted. The study shows that when the local leakage volume in the canal approaches or exceeds 100 m³/day, the planar influence range of the leakage exceeds 100 m. In the vertical direction, the stratum from the leakage center to the tunnel roof transitions from the vadose zone to the saturated zone, changing from an unsaturated to a saturated state. Comparing the simulation results of normal conditions with leakage conditions, the deformation curves at the canal bottom exhibit "W-shaped" and "V-shaped" patterns, respectively, with maximum settlements of 3.6 mm and 6.4 mm, and settlement trough widths of 27 m and 45 m. The results indicate that leakage at the canal bottom increases the depth of the settlement trough. This is because the leakage reduces the soil strength and alters the compression coefficient within the affected range, requiring greater deformation in the saturated soil layer to counteract stress changes.
When a shield tunnel passes under the main canal of the South-to-North Water Diversion Project, leakage at the bottom of the canal structure can lead to more severe hazards. Therefore, to study the disturbance deformation patterns under the coupling effects of bidirectional interactions, the FEFLOW software was used to simulate the influence range of groundwater seepage under different leakage conditions in the canal. The FLAC3D software was employed to establish a model of the canal-stratum-tunnel system, and numerical simulations of cooperative deformation under different construction conditions were conducted. The study shows that when the local leakage volume in the canal approaches or exceeds 100 m³/day, the planar influence range of the leakage exceeds 100 m. In the vertical direction, the stratum from the leakage center to the tunnel roof transitions from the vadose zone to the saturated zone, changing from an unsaturated to a saturated state. Comparing the simulation results of normal conditions with leakage conditions, the deformation curves at the canal bottom exhibit "W-shaped" and "V-shaped" patterns, respectively, with maximum settlements of 3.6 mm and 6.4 mm, and settlement trough widths of 27 m and 45 m. The results indicate that leakage at the canal bottom increases the depth of the settlement trough. This is because the leakage reduces the soil strength and alters the compression coefficient within the affected range, requiring greater deformation in the saturated soil layer to counteract stress changes.
2025, 50(6): 2400-2415.
doi: 10.3799/dqkx.2025.053
Abstract:
Dissolved organic matter (DOM) plays a vital role in the carbon cycling process of coastal wetlands. Seasonal changes in hydrological process in the coastal area will affect DOM composition, thus controlling nitrogen transport and transformation pathways. In this study, the coastal area of Lianyungang, Jiangsu Province, was selected as the study area to investigate the seasonal characteristics of DOM and its impacts on nitrogen transformations based on the hydrochemical data of groundwater, river water, and seawater, combined with three-dimensional fluorescence spectroscopy and UV-visible spectroscopy. The results show that DOM in coastal area includes three components, terrestrial source-like fulvic acid (C1), terrestrial source-like humic acid (C2) and microbial source-like protein fraction (C3). In the study area, the NH4-N and DOC concentrations gradually increased with closer proximity to the coast, the N concentration is associated to the DOM component characteristics. During the wet season, the groundwater was recharged by rainfall and river water, with exogenous macromolecules DOM infiltrated accompanied by NH4-N into groundwater. The aquifer is in biased reducing condition, and the nitrification process is inhibited. During the dry season, the interaction between salty and fresh water was weak, at when the higher C3 component in the groundwater. Meanwhile, the aquifer is in more oxidizing environment, promoting nitrification. In the intertidal groundwaters, the DOM is characterized by higher degree of humification, the abundance of NH4-N and DOC suggests the mineralization of N contained soil organic matter. Also, a longer retention time of water as well as a strong microbial activity is likely to promote the dissimilatory nitrate reduction to ammonium (DNRA) and lead to further accumulation of NH4-N.
Dissolved organic matter (DOM) plays a vital role in the carbon cycling process of coastal wetlands. Seasonal changes in hydrological process in the coastal area will affect DOM composition, thus controlling nitrogen transport and transformation pathways. In this study, the coastal area of Lianyungang, Jiangsu Province, was selected as the study area to investigate the seasonal characteristics of DOM and its impacts on nitrogen transformations based on the hydrochemical data of groundwater, river water, and seawater, combined with three-dimensional fluorescence spectroscopy and UV-visible spectroscopy. The results show that DOM in coastal area includes three components, terrestrial source-like fulvic acid (C1), terrestrial source-like humic acid (C2) and microbial source-like protein fraction (C3). In the study area, the NH4-N and DOC concentrations gradually increased with closer proximity to the coast, the N concentration is associated to the DOM component characteristics. During the wet season, the groundwater was recharged by rainfall and river water, with exogenous macromolecules DOM infiltrated accompanied by NH4-N into groundwater. The aquifer is in biased reducing condition, and the nitrification process is inhibited. During the dry season, the interaction between salty and fresh water was weak, at when the higher C3 component in the groundwater. Meanwhile, the aquifer is in more oxidizing environment, promoting nitrification. In the intertidal groundwaters, the DOM is characterized by higher degree of humification, the abundance of NH4-N and DOC suggests the mineralization of N contained soil organic matter. Also, a longer retention time of water as well as a strong microbial activity is likely to promote the dissimilatory nitrate reduction to ammonium (DNRA) and lead to further accumulation of NH4-N.
2025, 50(6): 2416-2427.
doi: 10.3799/dqkx.2024.098
Abstract:
In the karst area of Southwest China, water and soil leakage is serious, and topsoil fills and plugs the aquifer storage structure, changing the hydrodynamic parameters of the media field. In order to explore the influence of cavern plugging on aquifer seepage, a three-dimensional physical model of karst fissure-cavern was designed, and experiments on water storage-release seepage from karst fissures under different plugging rates and rainfall conditions were carried out. The results show that the karst water flow shows a three-stage decline pattern during baseflow recession. The initial flow rate and recession coefficient are affected by aquifer thickness, water level drop and permeability coefficient of media field. Clogging prolongs the storage time and accelerates the rate of water level fallback at the end of rainfall; At a clogging rate of more than 50%, there is a large reduction in the storage space, and the clogging medium retards the drainage significantly, slowing down the rate of water level fallback. Clogging rate and permeability coefficient K and water storage coefficient S is an exponential function of the relationship between the two parameters at the beginning of the plugging rapid decrease. Numerical simulation results show that the decrease of parameters K and S will cause the groundwater level to be elevated, leading to the instability of the groundwater level at the beginning and the end of rainfall, and weakening the ability to regulate the groundwater in karst aquifers.
In the karst area of Southwest China, water and soil leakage is serious, and topsoil fills and plugs the aquifer storage structure, changing the hydrodynamic parameters of the media field. In order to explore the influence of cavern plugging on aquifer seepage, a three-dimensional physical model of karst fissure-cavern was designed, and experiments on water storage-release seepage from karst fissures under different plugging rates and rainfall conditions were carried out. The results show that the karst water flow shows a three-stage decline pattern during baseflow recession. The initial flow rate and recession coefficient are affected by aquifer thickness, water level drop and permeability coefficient of media field. Clogging prolongs the storage time and accelerates the rate of water level fallback at the end of rainfall; At a clogging rate of more than 50%, there is a large reduction in the storage space, and the clogging medium retards the drainage significantly, slowing down the rate of water level fallback. Clogging rate and permeability coefficient K and water storage coefficient S is an exponential function of the relationship between the two parameters at the beginning of the plugging rapid decrease. Numerical simulation results show that the decrease of parameters K and S will cause the groundwater level to be elevated, leading to the instability of the groundwater level at the beginning and the end of rainfall, and weakening the ability to regulate the groundwater in karst aquifers.
2025, 50(6): 2428-2443.
doi: 10.3799/dqkx.2025.014
Abstract:
Discharge variability significantly impacts the sedimentary characteristics and growth processes of river-dominated shallow-water deltas. In this study it aims to explore the macroscopic morphology and internal architecture of deltas under different discharge variability conditions. Based on modern sedimentological and hydrological data, numerical simulations of deltaic sedimentation under varying discharge conditions were conducted using a hydrodynamic modeling software. The findings indicate that flow variation controls channel migration rates and avulsion frequencies, thereby influencing the geomorphic and architectural features of deltas. Under high flow variation conditions, deltas exhibit fan-shaped geometries, frequent avulsion, bifurcation, and abandonment of distributary channels, resulting in complex channel networks. Channel numbers increase significantly, sedimentary material expands laterally, delta areas grow larger, and shorelines become smoother. In contrast, under low flow variation conditions, deltas are primarily bird-foot shaped, with fewer and more stable distributary channels. Sediments concentrate at the river mouth, and shoreline roughness is higher. These findings provide a scientific basis for analyzing similar deltaic sedimentary patterns and predicting hydrocarbon reservoir architectures.
Discharge variability significantly impacts the sedimentary characteristics and growth processes of river-dominated shallow-water deltas. In this study it aims to explore the macroscopic morphology and internal architecture of deltas under different discharge variability conditions. Based on modern sedimentological and hydrological data, numerical simulations of deltaic sedimentation under varying discharge conditions were conducted using a hydrodynamic modeling software. The findings indicate that flow variation controls channel migration rates and avulsion frequencies, thereby influencing the geomorphic and architectural features of deltas. Under high flow variation conditions, deltas exhibit fan-shaped geometries, frequent avulsion, bifurcation, and abandonment of distributary channels, resulting in complex channel networks. Channel numbers increase significantly, sedimentary material expands laterally, delta areas grow larger, and shorelines become smoother. In contrast, under low flow variation conditions, deltas are primarily bird-foot shaped, with fewer and more stable distributary channels. Sediments concentrate at the river mouth, and shoreline roughness is higher. These findings provide a scientific basis for analyzing similar deltaic sedimentary patterns and predicting hydrocarbon reservoir architectures.
2025, 50(6): 2444-2451.
doi: 10.3799/dqkx.2024.146
Abstract:
Silicate serves as a crucial nutrient for diatoms, which are capable of absorbing dissolved silicon from their surroundings through Silicon Transporter (SIT), thus playing a significant role in the global ocean's silicon cycle. Recent studies have indicated that marine single-celled Synechococcus also has the ability to accumulate silicon. Given that the evolution of Synechococcus predates that of diatoms, it is postulated that Synechococcus may utilize transporters such as SIT found in diatoms, to absorb dissolved silicon in the ocean. This research delves into the silicon accumulation in Synechococcus sp. XM24, particularly focusing on two key aspects. Firstly, the study investigates the potential presence of SIT in Synechococcus sp. XM24 under the condition of Depleted-Repleted silicate. Subsequently, two gene sequences suspected to encode SIT, were identified, and their protein sequences and functions were successfully predicted, shedding light on their involvement in membrane transport processes. Finally, AutoDock4 software was used to predict the active site of the protein.
Silicate serves as a crucial nutrient for diatoms, which are capable of absorbing dissolved silicon from their surroundings through Silicon Transporter (SIT), thus playing a significant role in the global ocean's silicon cycle. Recent studies have indicated that marine single-celled Synechococcus also has the ability to accumulate silicon. Given that the evolution of Synechococcus predates that of diatoms, it is postulated that Synechococcus may utilize transporters such as SIT found in diatoms, to absorb dissolved silicon in the ocean. This research delves into the silicon accumulation in Synechococcus sp. XM24, particularly focusing on two key aspects. Firstly, the study investigates the potential presence of SIT in Synechococcus sp. XM24 under the condition of Depleted-Repleted silicate. Subsequently, two gene sequences suspected to encode SIT, were identified, and their protein sequences and functions were successfully predicted, shedding light on their involvement in membrane transport processes. Finally, AutoDock4 software was used to predict the active site of the protein.
