The Xining Basin is located in the northeastern Qinghai-Tibetan Plateau, and its continuous Cenozoic strata record the entire uplift and outgrowth history of the Tibetan Plateau during the Cenozoic. The newly obtained...The Xining Basin is located in the northeastern Qinghai-Tibetan Plateau, and its continuous Cenozoic strata record the entire uplift and outgrowth history of the Tibetan Plateau during the Cenozoic. The newly obtained apatite fission track data presented here shows that the Xining Basin and two marginal mountain ranges have experienced multiphase rapid cooling since the Jurassic, as follows. In the Middle-Late Jurassic, the rapid exhumation of the former Xining Basin resulted from collision between the Qiangtang Block and the Tarim Block. During the Early-Late Cretaceous, the former Xining Basin underwent a tectonic event due to marginal compression, causing the angular unconformity between the Upper and Lower Cretaceous. In the Late Cretaceous to the Early Cenozoic, collision between the Qiangtang Block and the Lhasa Block may have resulted in the rapid exhumation of the Xining Basin and the Lajishan to the south. In the Early Cenozoic （ca. 50-30 Ma）, collision between the Indian and Eurasia plates affected the region that corresponds to the present northeastern Qinghai-Tibetan Plateau. During this period, the central Qilian Block rotated clockwise by approximately 24° to form a wedge-shaped basin （i.e., the Xining Basin） opening to the west. During ca. 17-8 Ma, the entire northeastern Qinghai-Tibetan Plateau underwent dramatic deformation, and the Lajishan uplifted rapidly owing to the northward compression of the Guide Basin from the south. A marked change in subsidence occurred in the Xining Basin during this period, when the basin was tectonically inverted.展开更多
The Xining basin is located in the northeastern margin of the Qinghai-Tibet Plateau. It is a rift basin formed in Mesozoic and Cenozoic and structurally belongs to the intersection of Kunlun and Qilian Mountains. Ceno...The Xining basin is located in the northeastern margin of the Qinghai-Tibet Plateau. It is a rift basin formed in Mesozoic and Cenozoic and structurally belongs to the intersection of Kunlun and Qilian Mountains. Cenozoic fluvial and lacustrine sedimentary strata are continuous in the Xining basin, with a thickness of more than 800 m, completely recording the deformation uplifting, weathering and denudation history and climate change process of the northeastern plateau. Currently, early Miocene Xijia fauna, early Middle Miocene Danshuilu fauna and late Middle Miocene Diaogou fauna are discovered in the Xining basin, which provide an important basis for the stratigraphic correlation of the Cenozoic strata in the Xining basin. However, in the next few decades, there are no reports about the large mammal fossils in the Xining basin, especially about late Miocene fauna. The author discovered a large amount of mammal fossils in the Neogene sedimentary strata in Huzhu area, Xining basin. According to the identification results of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, these fossils mainly included Hipparion dongxiangense, Chilotherium sp., Parelasmotherium sp., Stephanocemas sp. and Kubanochoerus sp. and their age was early Late Miocene. Since the discovery of this set of fossils directly filled the blank that there were no large mammal fossils in the Xining basin in Late Miocene, it was very important for studying the magnetic stratigraphic chronology of fossil-forming strata and establishing the paleomagnetic chronology scale plate of mammal fossils. In this paper, the paleomagnetic data of the fossil-forming stratigraphic profile, Banyan profile, were measured and the paleomagnetic records were collected through high density sampling, and finally the paleomagnetic polarity column of the profile was established. The results showed that five positive and five negative polarity segments were recorded in Banyan profile, which corresponded well to the polarity between C3 Br.1 n-C4 n.2 n in the standard polarity column. The age of profile top was about 7.25 Ma and profile bottom was about 8.4 Ma, with an age range of 1.15 Ma. The mammal fossils discovered this time were exposed between positive and negative polarities N5 and R5 at the bottom of the profile, corresponding to C4 r.1 r at negative polarity and C4 n.2 n at positive polarity in the standard polarity column. The age of mammal fossils was about 8.3 Ma. The paleomagnetic chronology of the strata and paleontological fossils determined the absolute age of late Miocene mammal fossils and expanded the upper age of late Miocene Xianshuihe Formation(N1 xn) in the Xining basin, which had provided new basic data for further studying the stratigraphic deposition and correlation of late Cenozoic strata and regional environmental evolution.展开更多
Objective Xining basin is located in the northeastern Qinghai- Tibetan Plateau, which tectonic location belongs to a junction of the Kunlun and Qilian mountains. The southern, northern and western parts of the basin a...Objective Xining basin is located in the northeastern Qinghai- Tibetan Plateau, which tectonic location belongs to a junction of the Kunlun and Qilian mountains. The southern, northern and western parts of the basin are restricted by the Laji, Daban and Riyue mountains fault zones, and go eastward into the Longzhong basin in Gansu Province. A succession of Cenozoic lacustrine sedimentary strata has been well developed in the Xining basin, with sediments over 800 m thick.展开更多
The northeastern Tibetan Plateau began to grow during the Eocene and it is important to understand the climatic history of Asia during this period of so-called ‘doubthouse' conditions. However, despite major adva...The northeastern Tibetan Plateau began to grow during the Eocene and it is important to understand the climatic history of Asia during this period of so-called ‘doubthouse' conditions. However, despite major advances in the last few decades,the evolutionary history and possible mechanisms of Eocene climate change in the northeastern Tibetan Plateau remain unclear.The Xining Basin in the northeastern Tibetan Plateau contains a continuous sequence of Early to Late Eocene non-marine sediments which provides the opportunity to resolve long-term climate changes during this period. In this study, we report the results of analyses of lithofacies, sediment color and geochemistry of bulk samples collected from the Xijigou section of the Xining Basin. An abrupt lithofacies change between the Early(~52–40 Ma) and Late Eocene(~40–34 Ma) indicates a change in the depositional environment from a shallow lake to a playa lake in response to a significant climatic shift. During ~52–40 Ma,higher values of sediment redness(a*), redness/lightness(a*/L*) and higher modified Chemical Index of Weathering(CIW′)indicate a relatively warm and humid climate, while from ~40–34 Ma the lower values of a*, a*/L*and lower CIW′ imply subhumid to semi-arid climatic conditions. The paleoclimatic records indicate a long-term(~52–34 Ma) trend of decreasing chemical weathering, consistent with global climate change. An abrupt sharp excursion of the proxy records during ~42–40 Ma suggests a relatively brief warm interval, corresponding to the Middle Eocene Climatic Optimum(MECO). We suggest that global cooling substantially reduced humidity in inner Asia, resulting in sub-humid to semi-arid climatic conditions after 40 Ma in the Xining Basin, which may have been responsible for the long-term trend of decreasing chemical weathering during the Eocene.展开更多
The Xining and the Minhe Basins bordering on each other around Ledu innorthwestern China cover a wide area from the west of Lanzhou in Gansuprovince to the east of Xining in Qinghai province.In these inland basins,Mes...The Xining and the Minhe Basins bordering on each other around Ledu innorthwestern China cover a wide area from the west of Lanzhou in Gansuprovince to the east of Xining in Qinghai province.In these inland basins,Meso-Cenozoic terrestrial deposits about 6000-7000 meters in thicknessand rich in mineral resources,such as coal,oi1 as well as salts,had beenaccumunated,which yield abundant organic remains comprising microfossils,such as nonmarine ostracods,charophytes,spores and pollen and macrofos-si1s including bivalves.gastropods,esthierians,fishes,reptiles and plants.展开更多
An increasing number of geological hazards along high-speed railways on the Qinghai-Tibetan Plateau have occurred and have resulted in a profound influence on old infrastructure,which has attracted increasing attentio...An increasing number of geological hazards along high-speed railways on the Qinghai-Tibetan Plateau have occurred and have resulted in a profound influence on old infrastructure,which has attracted increasing attention.The landslide event that occurred on September 15,2022,in Jiujiawan village,Xining city,Qinghai Province,is a typical case.Based on field investigations and remote sensing interpretations,a comprehensive analysis was conducted on the landslide.Additionally,the potential secondary failure of the current Jiujiawan landslide was assessed using Fast Lagrangian Analysis of Continua in Three Dimensions(FLAC3D).Based on the application of the small baseline subset-interferometric synthetic aperture radar(SBAS-InSAR)technique to SAR images from February 24,2017 to September 14,2022,a significant westward horizontal deformation was found to have been formed prior to the occurrence of the landslide.The maximum annual average deformation rate in the line of sight(LOS)direction reached-45 mm/yr,with a maximum cumulative deformation of-178 mm.This value was consistent with the continual increase in annual precipitation(2.51 mm/yr)prior to the occurrence of the landslide.The accumulated precipitation before the landslide was 279.8 mm,accounting for 54.2%of the total annual precipitation,with a particularly notable surge in monthly precipitation observed during August(250.3 mm).Additionally,the occurrence of a seismic event with a magnitude of Ms 6.9 in Menyuan County,80 km away from Xining,could be a potential triggering factor to the landslide,as evidenced by an abrupt subsidence alteration observed prior to and following the earthquake.The maximum subsidence in the line of sight(LOS)direction exceeded 11 mm,exhibiting a highly consistent spatial distribution with the occurrence range of landslides.These results suggest that the Jiujiawan landslide was likely induced by earthquake events in the early stage and heavy rainfall in the later stage.The FLAC3D numerical simulation show that after the landslide,the slope remained marginally stable under natural conditions;however,it is susceptible to reactivation with heavy rainfall.展开更多
In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L...In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.展开更多
This work established an evaluation index system based on a comprehensive analysis of those factors affecting the suitability of CO2 geological storage.This evaluation index system includes three evaluation index laye...This work established an evaluation index system based on a comprehensive analysis of those factors affecting the suitability of CO2 geological storage.This evaluation index system includes three evaluation index layers of geological safety,storage scale and social economy,nine evaluation index sub-layers,and 28 evaluation index factors,and adopts the analytic hierarchy process（AHP）and index overlay methods.Taking the Xining Basin in northwest China as an example,we conducted comprehensive analysis of geological conditions and performed quantitative evaluation based on this evaluation index system,which indicates that the Shuangshu depression of the Xining Basin is comparatively suitable for CO2 geological storage.It is suggested that this evaluation index system and the evaluation method proposed in this study are suitable for most continental sedimentary basins in China and should be widely applied.展开更多
基金granted by the China Geological Survey Project("Study on the neotectonics of China and its relationship with the earthquake")the Scientific Special Projects of Institute of Geology,CAGS(No.J1121)
文摘The Xining Basin is located in the northeastern Qinghai-Tibetan Plateau, and its continuous Cenozoic strata record the entire uplift and outgrowth history of the Tibetan Plateau during the Cenozoic. The newly obtained apatite fission track data presented here shows that the Xining Basin and two marginal mountain ranges have experienced multiphase rapid cooling since the Jurassic, as follows. In the Middle-Late Jurassic, the rapid exhumation of the former Xining Basin resulted from collision between the Qiangtang Block and the Tarim Block. During the Early-Late Cretaceous, the former Xining Basin underwent a tectonic event due to marginal compression, causing the angular unconformity between the Upper and Lower Cretaceous. In the Late Cretaceous to the Early Cenozoic, collision between the Qiangtang Block and the Lhasa Block may have resulted in the rapid exhumation of the Xining Basin and the Lajishan to the south. In the Early Cenozoic （ca. 50-30 Ma）, collision between the Indian and Eurasia plates affected the region that corresponds to the present northeastern Qinghai-Tibetan Plateau. During this period, the central Qilian Block rotated clockwise by approximately 24° to form a wedge-shaped basin （i.e., the Xining Basin） opening to the west. During ca. 17-8 Ma, the entire northeastern Qinghai-Tibetan Plateau underwent dramatic deformation, and the Lajishan uplifted rapidly owing to the northward compression of the Guide Basin from the south. A marked change in subsidence occurred in the Xining Basin during this period, when the basin was tectonically inverted.
基金granted by the National Natural Science Foundation of China (Grant No. 41772381)the Chinese Academy of Geological Sciences Research Fund (Grant Nos. YYWF201511 and DZLXJK201710)the Geological Investigation Project of China Geological Survey (Grant Nos. 121201234000160014, 12120113006100, 121201104000150009 and DD20160083)
文摘The Xining basin is located in the northeastern margin of the Qinghai-Tibet Plateau. It is a rift basin formed in Mesozoic and Cenozoic and structurally belongs to the intersection of Kunlun and Qilian Mountains. Cenozoic fluvial and lacustrine sedimentary strata are continuous in the Xining basin, with a thickness of more than 800 m, completely recording the deformation uplifting, weathering and denudation history and climate change process of the northeastern plateau. Currently, early Miocene Xijia fauna, early Middle Miocene Danshuilu fauna and late Middle Miocene Diaogou fauna are discovered in the Xining basin, which provide an important basis for the stratigraphic correlation of the Cenozoic strata in the Xining basin. However, in the next few decades, there are no reports about the large mammal fossils in the Xining basin, especially about late Miocene fauna. The author discovered a large amount of mammal fossils in the Neogene sedimentary strata in Huzhu area, Xining basin. According to the identification results of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, these fossils mainly included Hipparion dongxiangense, Chilotherium sp., Parelasmotherium sp., Stephanocemas sp. and Kubanochoerus sp. and their age was early Late Miocene. Since the discovery of this set of fossils directly filled the blank that there were no large mammal fossils in the Xining basin in Late Miocene, it was very important for studying the magnetic stratigraphic chronology of fossil-forming strata and establishing the paleomagnetic chronology scale plate of mammal fossils. In this paper, the paleomagnetic data of the fossil-forming stratigraphic profile, Banyan profile, were measured and the paleomagnetic records were collected through high density sampling, and finally the paleomagnetic polarity column of the profile was established. The results showed that five positive and five negative polarity segments were recorded in Banyan profile, which corresponded well to the polarity between C3 Br.1 n-C4 n.2 n in the standard polarity column. The age of profile top was about 7.25 Ma and profile bottom was about 8.4 Ma, with an age range of 1.15 Ma. The mammal fossils discovered this time were exposed between positive and negative polarities N5 and R5 at the bottom of the profile, corresponding to C4 r.1 r at negative polarity and C4 n.2 n at positive polarity in the standard polarity column. The age of mammal fossils was about 8.3 Ma. The paleomagnetic chronology of the strata and paleontological fossils determined the absolute age of late Miocene mammal fossils and expanded the upper age of late Miocene Xianshuihe Formation(N1 xn) in the Xining basin, which had provided new basic data for further studying the stratigraphic deposition and correlation of late Cenozoic strata and regional environmental evolution.
基金financially supported by the Chinese Academy of Geological Sciences Research Fund(Grant Nos.YYWF201511,DZLXJK201710,DZLXJK201405)the Geological Investigation Project of China Geological Survey(Grant Nos.12120113006100, 121201234000160014-4,121201101000150013)
文摘Objective Xining basin is located in the northeastern Qinghai- Tibetan Plateau, which tectonic location belongs to a junction of the Kunlun and Qilian mountains. The southern, northern and western parts of the basin are restricted by the Laji, Daban and Riyue mountains fault zones, and go eastward into the Longzhong basin in Gansu Province. A succession of Cenozoic lacustrine sedimentary strata has been well developed in the Xining basin, with sediments over 800 m thick.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41430531 & 41690114)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB26020201)the International Partnership Program of Chinese Academy of Sciences (Grant No. 131C11KYSB20160061)
文摘The northeastern Tibetan Plateau began to grow during the Eocene and it is important to understand the climatic history of Asia during this period of so-called ‘doubthouse' conditions. However, despite major advances in the last few decades,the evolutionary history and possible mechanisms of Eocene climate change in the northeastern Tibetan Plateau remain unclear.The Xining Basin in the northeastern Tibetan Plateau contains a continuous sequence of Early to Late Eocene non-marine sediments which provides the opportunity to resolve long-term climate changes during this period. In this study, we report the results of analyses of lithofacies, sediment color and geochemistry of bulk samples collected from the Xijigou section of the Xining Basin. An abrupt lithofacies change between the Early(~52–40 Ma) and Late Eocene(~40–34 Ma) indicates a change in the depositional environment from a shallow lake to a playa lake in response to a significant climatic shift. During ~52–40 Ma,higher values of sediment redness(a*), redness/lightness(a*/L*) and higher modified Chemical Index of Weathering(CIW′)indicate a relatively warm and humid climate, while from ~40–34 Ma the lower values of a*, a*/L*and lower CIW′ imply subhumid to semi-arid climatic conditions. The paleoclimatic records indicate a long-term(~52–34 Ma) trend of decreasing chemical weathering, consistent with global climate change. An abrupt sharp excursion of the proxy records during ~42–40 Ma suggests a relatively brief warm interval, corresponding to the Middle Eocene Climatic Optimum(MECO). We suggest that global cooling substantially reduced humidity in inner Asia, resulting in sub-humid to semi-arid climatic conditions after 40 Ma in the Xining Basin, which may have been responsible for the long-term trend of decreasing chemical weathering during the Eocene.
文摘The Xining and the Minhe Basins bordering on each other around Ledu innorthwestern China cover a wide area from the west of Lanzhou in Gansuprovince to the east of Xining in Qinghai province.In these inland basins,Meso-Cenozoic terrestrial deposits about 6000-7000 meters in thicknessand rich in mineral resources,such as coal,oi1 as well as salts,had beenaccumunated,which yield abundant organic remains comprising microfossils,such as nonmarine ostracods,charophytes,spores and pollen and macrofos-si1s including bivalves.gastropods,esthierians,fishes,reptiles and plants.
基金supported by the Natural Science Foundation of Qinghai Province,China(No.2024-SF-129).
文摘An increasing number of geological hazards along high-speed railways on the Qinghai-Tibetan Plateau have occurred and have resulted in a profound influence on old infrastructure,which has attracted increasing attention.The landslide event that occurred on September 15,2022,in Jiujiawan village,Xining city,Qinghai Province,is a typical case.Based on field investigations and remote sensing interpretations,a comprehensive analysis was conducted on the landslide.Additionally,the potential secondary failure of the current Jiujiawan landslide was assessed using Fast Lagrangian Analysis of Continua in Three Dimensions(FLAC3D).Based on the application of the small baseline subset-interferometric synthetic aperture radar(SBAS-InSAR)technique to SAR images from February 24,2017 to September 14,2022,a significant westward horizontal deformation was found to have been formed prior to the occurrence of the landslide.The maximum annual average deformation rate in the line of sight(LOS)direction reached-45 mm/yr,with a maximum cumulative deformation of-178 mm.This value was consistent with the continual increase in annual precipitation(2.51 mm/yr)prior to the occurrence of the landslide.The accumulated precipitation before the landslide was 279.8 mm,accounting for 54.2%of the total annual precipitation,with a particularly notable surge in monthly precipitation observed during August(250.3 mm).Additionally,the occurrence of a seismic event with a magnitude of Ms 6.9 in Menyuan County,80 km away from Xining,could be a potential triggering factor to the landslide,as evidenced by an abrupt subsidence alteration observed prior to and following the earthquake.The maximum subsidence in the line of sight(LOS)direction exceeded 11 mm,exhibiting a highly consistent spatial distribution with the occurrence range of landslides.These results suggest that the Jiujiawan landslide was likely induced by earthquake events in the early stage and heavy rainfall in the later stage.The FLAC3D numerical simulation show that after the landslide,the slope remained marginally stable under natural conditions;however,it is susceptible to reactivation with heavy rainfall.
基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0905)the National Natural Science Foundation of China(Grant Nos.42002283,41572306,42041006 and 42062019)+2 种基金the Project of the Qinghai Science&Technology Department(Grant Nos.2020-ZJ-906 and 2014-ZJ-906)the Key Discipline Construction Project for Geological Resources and Geological Engineering of Qinghai University(Grant No.41250103)the Ministry of Education’s‘Innovative Team Development Scheme’(IRT17R62)。
文摘In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.
基金supported by the Land and Resources Survey Program from China Geological Survey(grant No. DD2016024012120113006600)+1 种基金Land and Resources Public Welfare Scientific Research Project(grant No. 201211063)National Natural Science Foundation of China(grant No.41502259)
文摘This work established an evaluation index system based on a comprehensive analysis of those factors affecting the suitability of CO2 geological storage.This evaluation index system includes three evaluation index layers of geological safety,storage scale and social economy,nine evaluation index sub-layers,and 28 evaluation index factors,and adopts the analytic hierarchy process（AHP）and index overlay methods.Taking the Xining Basin in northwest China as an example,we conducted comprehensive analysis of geological conditions and performed quantitative evaluation based on this evaluation index system,which indicates that the Shuangshu depression of the Xining Basin is comparatively suitable for CO2 geological storage.It is suggested that this evaluation index system and the evaluation method proposed in this study are suitable for most continental sedimentary basins in China and should be widely applied.
