The timing of onset of deposition of the Lulehe Formation is a significant factor in understanding the genesis of the Qaidam basin and the evolution of the Tibetan Plateau. Here, we describe a detailed magnetostratigr...The timing of onset of deposition of the Lulehe Formation is a significant factor in understanding the genesis of the Qaidam basin and the evolution of the Tibetan Plateau. Here, we describe a detailed magnetostratigraphic and magnetic fabric study of the middle and lower parts of the Lulehe Formation. A total of 234 samples were collected from 117 sites throughout a thickness of almost 460 m of fluvial and lacustrine deposits at the Xitieshan section in the northeastern Qaidam basin. Out of these sites, 94 sites yielded well-defined characteristic remanent magnetization components by stepwise thermal demagnetization and were used to establish the magnetostratigraphy of the studied section. Based on correlation with the geomagnetic polarity timescale, the studied section spans the period from 53.8 Ma to 50.7 Ma. Our results show a three-fold decrease in sedimentation rates as well as marked change in facies from braided river to delta and shore-shallow lake around 52.6 Ma, which suggests tectonic uplift of the northeastern Qaidam basin margin ridge was rapid at the onset of formation of the Qaidam basin and subsequently weakened after 52.6 Ma. The anisotropy of magnetic susceptibility results indicate that tectonic compression stress had reached the northeastern Tibetan Plateau by the early stages of Indo-Eurasian plate collision and that the direction of stress in the study area was NE-SW. Furthermore, a weakening of tectonic compression stress around 52.6 Ma is consistent with sedimentary records. The age of initial deposition of the Qaidam basin （around 53.8 Ma） was almost synchronous with that of the Qiangtang, Hoh Xil, Xining, and Lanzhou basins, which implies that stress was transferred rapidly through the Tibetan Plateau during or immediately after the onset of Indo-Eurasian collision.展开更多
As the global push for sustainable urban development progresses, this study, set against the backdrop of Hangzhou City,one of China's megacities, addressed the conflict between urban expansion and the occurrence o...As the global push for sustainable urban development progresses, this study, set against the backdrop of Hangzhou City,one of China's megacities, addressed the conflict between urban expansion and the occurrence of urban geological hazards.Focusing on the predominant geological hazards troubling Hangzhou-urban road collapse, land subsidence, and karst collapse-we introduced a Categorical Boosting-SHapley Additive exPlanations(CatBoost-SHAP) model. This model not only demonstrates strong performance in predicting the selected typical urban hazards, with area under the curve(AUC) values reaching 0.92, 0.92, and 0.94, respectively, but also, through the incorporation of the explainable model SHAP, visually presents the prediction process, the interrelations between evaluation factors, and the weight of each factor. Additionally, the study undertook a multi-hazard evaluation, producing a susceptibility zoning map for multiple hazards, while performing tailored analysis by integrating economic and population density factors of Hangzhou. This research enables urban decision makers to transcend the “black box” limitations of machine learning, facilitating informed decision making through strategic resource allocation and scheduling based on economic and demographic factors of the study area. This approach holds the potential to offer valuable insights for the sustainable development of cities worldwide.展开更多
Based on the data of 1:250000 geological mapping completed by CGS and the previous literature of the Cenozoic strata, 98 remnant basins and 5 stratigraphic realms with 13 stratigraphic subrealms have been recognized o...Based on the data of 1:250000 geological mapping completed by CGS and the previous literature of the Cenozoic strata, 98 remnant basins and 5 stratigraphic realms with 13 stratigraphic subrealms have been recognized on the Qinghai-Tibet Plateau and its adjacent area. Through the research of the types of remnant basins, tectonic setting, stratigraphic sequence and sedimentary characteristics, contact relationship between the strata, the formation time and evolution history of sediments, we divided the uplift process and sedimentary response of the Qinghai-Tibet Plateau into 3 stages and 8 sub-stages, namely, subduction-collision uplift stage (65-34 Ma) with three sub-stages, intercontinental convergence and compressive uplift stage (34-13 Ma) with three sub-stages, and intercontinental isostatic adjustment uplift stage (since 13 Ma) with two sub-stages.展开更多
The aim of this study is to quantify the geochemical elements distribution patterns analyzed from stream sediment data and then to delineate favorable areas for mineral exploration. A total of 7 270 stream sediment sa...The aim of this study is to quantify the geochemical elements distribution patterns analyzed from stream sediment data and then to delineate favorable areas for mineral exploration. A total of 7 270 stream sediment samples were collected from four subareas and 37 rock（ore） chip samples from five different locations in the Bange region, northern Tibet（China）. The multifractal spectra of 12 elements including Au, Ag, As, Cu, Mo, Pb, Zn, W, Sn, Bi, Sb and Hg are represented by the method of moments, and characterized by five quantitative multifractal parameters. The results show that the multifractality for Cu and Bi in the Gongma area is much stronger than those in other subareas. Both the asymmetry index of multifractal spectra and the variance coefficients of Cu and Bi in this area are the highest, which imply that the distribution pattern of Cu and Bi in the Gongma area is the most heterogeneous. These multifractal parameters indicate that the Gongma area is the most favorable for prospecting Cu and Bi. The results obtained by the method of moments are in agreement with petrochemical analysis and field observation. It is suggested that multifractal analysis can be used as an effective tool to evaluate the ore-forming potential in the study area and to provide new approaches for geochemical exploration.展开更多
This study provides the n-alkane and pollen records of the Holocene loess at Balong Town, Dulan County, Qinghai Province, and the environmental changes reconstructed from both records agreed well. Three stages of past...This study provides the n-alkane and pollen records of the Holocene loess at Balong Town, Dulan County, Qinghai Province, and the environmental changes reconstructed from both records agreed well. Three stages of past climate change were deciphered by variations of the n-alkane and pollen proxies. Before 5 370 a BP, the climate was warm-dry but slightly humid, corresponding to the Mid-Holocene climatic optimum; 5 370-3 830 a BP, the climate changed alternatively between warm-dry slightly humid and warm-dry, indicating the transition from the Mid-Holocene climatic optimum to the Late Holocene cold period; after 3 830 a BP, the climate was mainly warm-dry. The warm cool and extremely dry climate during 3 040-2 600 a BP was recorded by both the n-alkane and pollen proxies, suggesting the environment evolved into desert or salt lake, in accordance with the cold and highly frequent natural disaster period in the Western Zhou Dynasty （ca. 2 996-2 721 a BP） in China.展开更多
Clay mineralogy and bulk mineral composition of Tertiary sediments in Qaidam were investigated using X-ray diffraction （XRD） and scanning electron microscopy in order to better understand regional climate change res...Clay mineralogy and bulk mineral composition of Tertiary sediments in Qaidam were investigated using X-ray diffraction （XRD） and scanning electron microscopy in order to better understand regional climate change resulting from uplift of the Northeast Tibetan Plateau. Climate change in Qaidam since -53.5 Ma could be divided into four stages： a warm and seasonally arid climate between -53.5 and 40 Ma, a cold and arid climate from -40 to 26 Ma, a warm and humid climate between -26 and 13.5 Ma, and a much colder and arid climate from -13.5 to 2.5 Ma, respectively. The illite crystallinity and sedimentary facies suggested that uplift events took place around ＆gt;52–50, -40–38, -26–15, -10–8, and ＆lt;5 Ma inthe Qaidam region, respectively. The climate in Qaidam Basin could have been controlled by global climate prior to 13.5 Ma. As the Tibetan Plateau reached a significant elevation by -13.5 Ma, and the climate cycles of the East Asian monsoon might add additional influence.展开更多
Xiangxi River Basin, located in western Hubei Province in central China, is a karst ridge-trough area with an inhomogeneous and complicated distribution of water resources. This paper compares the characteristics of s...Xiangxi River Basin, located in western Hubei Province in central China, is a karst ridge-trough area with an inhomogeneous and complicated distribution of water resources. This paper compares the characteristics of surface and subsurface floods in this karst basin, utilizing a one-parameter Darcian model and the traditional exponential model. The observed hydrographs and inferred water components are strikingly similar for surface and subsurface floods. The Darcian model and the exponential model are based on different views of the flood generation process, with the former fitting the entire hydrograph with a single time constant, and the latter fitting only the recession limb with multiple time constants. Due to the anisotropy and heterogeneity of karst media, a combination of physical and chemical techniques including the use of 3S（remote sensing, geographical information system, global positioning system） method is proposed for an enhanced hydrological investigation to assess and characterize karst water resources in mountainous areas.展开更多
基金supported by Foundation of Geological Survey of China(no.1212011121261)the National Natural Science Foundation of China (no.40902049)+1 种基金the Special Fund for Basic Scienctific Research of Central Colleges, China University of Geoscience (Wuhan) (no.CUGL09206)the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences(no.GBL11207)
文摘The timing of onset of deposition of the Lulehe Formation is a significant factor in understanding the genesis of the Qaidam basin and the evolution of the Tibetan Plateau. Here, we describe a detailed magnetostratigraphic and magnetic fabric study of the middle and lower parts of the Lulehe Formation. A total of 234 samples were collected from 117 sites throughout a thickness of almost 460 m of fluvial and lacustrine deposits at the Xitieshan section in the northeastern Qaidam basin. Out of these sites, 94 sites yielded well-defined characteristic remanent magnetization components by stepwise thermal demagnetization and were used to establish the magnetostratigraphy of the studied section. Based on correlation with the geomagnetic polarity timescale, the studied section spans the period from 53.8 Ma to 50.7 Ma. Our results show a three-fold decrease in sedimentation rates as well as marked change in facies from braided river to delta and shore-shallow lake around 52.6 Ma, which suggests tectonic uplift of the northeastern Qaidam basin margin ridge was rapid at the onset of formation of the Qaidam basin and subsequently weakened after 52.6 Ma. The anisotropy of magnetic susceptibility results indicate that tectonic compression stress had reached the northeastern Tibetan Plateau by the early stages of Indo-Eurasian plate collision and that the direction of stress in the study area was NE-SW. Furthermore, a weakening of tectonic compression stress around 52.6 Ma is consistent with sedimentary records. The age of initial deposition of the Qaidam basin （around 53.8 Ma） was almost synchronous with that of the Qiangtang, Hoh Xil, Xining, and Lanzhou basins, which implies that stress was transferred rapidly through the Tibetan Plateau during or immediately after the onset of Indo-Eurasian collision.
基金supported by the China Geological Survey,Nanjing Center,Zhejiang Geological Survey,and China University of Geosciences(Wuhan)funded by the Laboratory of Geological Safety of Underground Space in Coastal Cities,Ministry of Natural Resources(Project No.BHKF2022Z02)the China Geological Survey,Nanjing Center(Project No.DD20190281).
文摘As the global push for sustainable urban development progresses, this study, set against the backdrop of Hangzhou City,one of China's megacities, addressed the conflict between urban expansion and the occurrence of urban geological hazards.Focusing on the predominant geological hazards troubling Hangzhou-urban road collapse, land subsidence, and karst collapse-we introduced a Categorical Boosting-SHapley Additive exPlanations(CatBoost-SHAP) model. This model not only demonstrates strong performance in predicting the selected typical urban hazards, with area under the curve(AUC) values reaching 0.92, 0.92, and 0.94, respectively, but also, through the incorporation of the explainable model SHAP, visually presents the prediction process, the interrelations between evaluation factors, and the weight of each factor. Additionally, the study undertook a multi-hazard evaluation, producing a susceptibility zoning map for multiple hazards, while performing tailored analysis by integrating economic and population density factors of Hangzhou. This research enables urban decision makers to transcend the “black box” limitations of machine learning, facilitating informed decision making through strategic resource allocation and scheduling based on economic and demographic factors of the study area. This approach holds the potential to offer valuable insights for the sustainable development of cities worldwide.
基金supported by Geological Survey of China (Grant Nos.1212010610103 and 1212010733802)National Natural Science Founda-tion of China (Grant Nos.40921062 and 400830212)MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences
文摘Based on the data of 1:250000 geological mapping completed by CGS and the previous literature of the Cenozoic strata, 98 remnant basins and 5 stratigraphic realms with 13 stratigraphic subrealms have been recognized on the Qinghai-Tibet Plateau and its adjacent area. Through the research of the types of remnant basins, tectonic setting, stratigraphic sequence and sedimentary characteristics, contact relationship between the strata, the formation time and evolution history of sediments, we divided the uplift process and sedimentary response of the Qinghai-Tibet Plateau into 3 stages and 8 sub-stages, namely, subduction-collision uplift stage (65-34 Ma) with three sub-stages, intercontinental convergence and compressive uplift stage (34-13 Ma) with three sub-stages, and intercontinental isostatic adjustment uplift stage (since 13 Ma) with two sub-stages.
基金financially supported by the Special Project on Mineral Exploration and Assessment in Tibetan Plateau (No. 1212010818038)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (No. IRT1083)the National Natural Science Foundation of China (No. 41272362)
文摘The aim of this study is to quantify the geochemical elements distribution patterns analyzed from stream sediment data and then to delineate favorable areas for mineral exploration. A total of 7 270 stream sediment samples were collected from four subareas and 37 rock（ore） chip samples from five different locations in the Bange region, northern Tibet（China）. The multifractal spectra of 12 elements including Au, Ag, As, Cu, Mo, Pb, Zn, W, Sn, Bi, Sb and Hg are represented by the method of moments, and characterized by five quantitative multifractal parameters. The results show that the multifractality for Cu and Bi in the Gongma area is much stronger than those in other subareas. Both the asymmetry index of multifractal spectra and the variance coefficients of Cu and Bi in this area are the highest, which imply that the distribution pattern of Cu and Bi in the Gongma area is the most heterogeneous. These multifractal parameters indicate that the Gongma area is the most favorable for prospecting Cu and Bi. The results obtained by the method of moments are in agreement with petrochemical analysis and field observation. It is suggested that multifractal analysis can be used as an effective tool to evaluate the ore-forming potential in the study area and to provide new approaches for geochemical exploration.
基金supported by China Geological Survey (Nos.1212011121261 and 1212011121224)
文摘This study provides the n-alkane and pollen records of the Holocene loess at Balong Town, Dulan County, Qinghai Province, and the environmental changes reconstructed from both records agreed well. Three stages of past climate change were deciphered by variations of the n-alkane and pollen proxies. Before 5 370 a BP, the climate was warm-dry but slightly humid, corresponding to the Mid-Holocene climatic optimum; 5 370-3 830 a BP, the climate changed alternatively between warm-dry slightly humid and warm-dry, indicating the transition from the Mid-Holocene climatic optimum to the Late Holocene cold period; after 3 830 a BP, the climate was mainly warm-dry. The warm cool and extremely dry climate during 3 040-2 600 a BP was recorded by both the n-alkane and pollen proxies, suggesting the environment evolved into desert or salt lake, in accordance with the cold and highly frequent natural disaster period in the Western Zhou Dynasty （ca. 2 996-2 721 a BP） in China.
基金supported by the China Geological Survey(No.1212011121261)the National Natural Science Foundation of China(Nos.41272053and41072030)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20110145110001)the Independent Research Project Foundation of State Key Laboratory of Biogeology and Envi-ronmental Geology,China University of Geosciences,Wuhan(No.GBL11307)
文摘Clay mineralogy and bulk mineral composition of Tertiary sediments in Qaidam were investigated using X-ray diffraction （XRD） and scanning electron microscopy in order to better understand regional climate change resulting from uplift of the Northeast Tibetan Plateau. Climate change in Qaidam since -53.5 Ma could be divided into four stages： a warm and seasonally arid climate between -53.5 and 40 Ma, a cold and arid climate from -40 to 26 Ma, a warm and humid climate between -26 and 13.5 Ma, and a much colder and arid climate from -13.5 to 2.5 Ma, respectively. The illite crystallinity and sedimentary facies suggested that uplift events took place around ＆gt;52–50, -40–38, -26–15, -10–8, and ＆lt;5 Ma inthe Qaidam region, respectively. The climate in Qaidam Basin could have been controlled by global climate prior to 13.5 Ma. As the Tibetan Plateau reached a significant elevation by -13.5 Ma, and the climate cycles of the East Asian monsoon might add additional influence.
基金supported by the China Geological Survey (No. 12120113103800)
文摘Xiangxi River Basin, located in western Hubei Province in central China, is a karst ridge-trough area with an inhomogeneous and complicated distribution of water resources. This paper compares the characteristics of surface and subsurface floods in this karst basin, utilizing a one-parameter Darcian model and the traditional exponential model. The observed hydrographs and inferred water components are strikingly similar for surface and subsurface floods. The Darcian model and the exponential model are based on different views of the flood generation process, with the former fitting the entire hydrograph with a single time constant, and the latter fitting only the recession limb with multiple time constants. Due to the anisotropy and heterogeneity of karst media, a combination of physical and chemical techniques including the use of 3S（remote sensing, geographical information system, global positioning system） method is proposed for an enhanced hydrological investigation to assess and characterize karst water resources in mountainous areas.
