The Mesoproterozoic Kunyang rift, which is located on the western margin of the Yangtze platform and the southern section of the Kangdian axis, is a rare massive Precambrian iron-copper polymetallic mineralization zon...The Mesoproterozoic Kunyang rift, which is located on the western margin of the Yangtze platform and the southern section of the Kangdian axis, is a rare massive Precambrian iron-copper polymetallic mineralization zone in China. The Mesoproterozoic Wulu (Wuding-Lufeng) basin in the middle of the rift is an elliptic basin controlled by a ring fracture system. Moreover, volcanic activities in the basin display zonation of an outer ring, a middle ring and an inner ring with carbonatitic volcanic rocks and sub-volcanic dykes discovered in the outer and middle rings. The Sm-Nd isochron ages have been determined for the outer-ring carbonatitic lavas (1685 Ma) and basaltic porphyrite of the radiating dyke swarm (1645 Ma) and the Rb-Sr isochron ages for the out-ring carbonatitic lavas (893 Ma) and the middle-ring dykes (1048 Ma). In combination of the U-Pb concordant ages of zircon (1743 Ma) in trachy-andesite of the corresponding period and stratum (1569 Ma) of the Etouchang Formation, as well as the Rb-Sr isochron age (1024 Ma) and K-Ar age (1186 Ma) of the dykes in the middle ring, the age of carbonarites in the basin is preliminarily determined. It is ensured that all of these carbonatites were formed in the Mesoprotero/oic period, whereby two stages could be identified as follows: in the first stage, carbonatitic volcanic groups, such as lavas, pyroclastic rocks and volcaniclastic sedimentary rocks, were formed in the outer ring; in the second stage, carbonatitic breccias and dykes appeared in the middle ring. The metamorphic age of the carbonatitic lavas in the outer ring was determined to be concurrent with the end of the first stage of the Neoproterozoic period, corresponding to the Jinning movement in central Yunnan.展开更多
Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land,forestland,grassland,farmland,and bare land in the Dachunh...Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land,forestland,grassland,farmland,and bare land in the Dachunhe watershed of Jinning District,Kunming City,Yunnan Province,China.The effects of the soil organic carbon,total nitrogen stratification ratio,soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed.The results show that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed are statistically significant(P<0.05).The organic carbon and total nitrogen stratification ratio SR1 of garden land soil are 38.5%and 25.3%,respectively,which are higher than SR^(2).The soil organic carbon and total nitrogen stratification ratio SR^(2) of different land-use types are greater than SR1.There are statistically significant differences in the SR^(2) soil organic carbon and total nitrogen stratification ratios(P<0.05).Soil organic carbon and total nitrogen storage of diffe-rent land-use types gradually decrease with increasing soil depth,with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer.Soil organic carbon and total nitrogen sto-rage at the same soil depth are significantly different(P<0.05).Soil organic carbon and total nitrogen storage in the garden land are greater than those in the other land-use types.Soil organic carbon and total nitrogen storage in 0-20 cm garden land are 4.96 and 3.19 times than those in bare land,respectively;soil organic carbon and total nitrogen storage are explained by 93.66%and 1.53%in redundancy analysis RDA1 and RDA2,respectively.All physicochemical factors except Available Phosphorus and pH are statistically significance with carbon and nitrogen storage(P<0.05).Soil cationic exchange capacity,Available Phosphorus,C/N ratio,and Moisture Content are positively correlated with organic carbon and total nitrogen storage.In contrast,soil Bulk Density is negatively correlated with organic carbon storage and total nitrogen storage.Available Phosphorus,C/N ratio,and Moisture Content are the main factors promoting soil organic carbon and total nitrogen accumulation.展开更多
This paper analyzes the necessity of mountain tourism development in central Yunnan from the aspects of market demand,rural industrial structure optimization demand,characteristic minority culture protection demand,ec...This paper analyzes the necessity of mountain tourism development in central Yunnan from the aspects of market demand,rural industrial structure optimization demand,characteristic minority culture protection demand,ecological environment protection demand,beautiful rural construction demand and so on.On this basis,against the backdrop of rural revitalization strategy,the path of mountain tourism development in central Yunnan is analyzed.展开更多
[ Ob.jeetive] The research aimed to analyze characteristics of the meteorological drought in central Yunnan. [ Method] Based on precipi- tation data at 43 meteorological stations of the central Yunnan, SPI at year sca...[ Ob.jeetive] The research aimed to analyze characteristics of the meteorological drought in central Yunnan. [ Method] Based on precipi- tation data at 43 meteorological stations of the central Yunnan, SPI at year scale in each station was calculated, and occurrence frequency of the drought at different grades was conducted statistics. Finally, spline curve interpolation method was used to acquire spatial distribution characteristics of the occurrence frequencies for various-level droughts in central Yunnan. [ Result] The drought has experienced the following four stages since 1960 in central Yunnan. Firstly, SPI had obvious decrease trend, and drought had the tendency to become severe in the 1970s. Secondly, in the 1960s and the 1980s, although variation of the SPI was large, we didn＇t find any distinct changing trend. Thirdly, SPI showed an evident increasing trend from the late 1980s to 2000. That was to say, central Yunnan experienced a wet period within those years. Lastly, the drought became severe from 2001 to 2009. Honghe, Yuanjiang, Binchuan, Luquan and Zhanyi tended to suffer from the medium drought; Kunming, Chenggong, Qujing, northeast Chuxiong, Dali, east Yangbi and central Yuxi tended to suffer from the severe drought; Zhanyi, Binchuan, west Dayao, Xiangyun, north Qujing, Anning and northwest Kunming tended to suffer from the extreme drought. [ Conclusion] The research provided theoreticai basis for drought prevention and control in the zone.展开更多
The Haizi diabase-granite porphyry composite rock mass is located in the Wuding-Yanjing taphrogenic trough within the Paleoproterozoic Kangdian fault-uplift zone. According to field observations, the diabase is divide...The Haizi diabase-granite porphyry composite rock mass is located in the Wuding-Yanjing taphrogenic trough within the Paleoproterozoic Kangdian fault-uplift zone. According to field observations, the diabase is divided into two types: central facies and marginal facies;the granite porphyry directly contacts the central facies of diabase without transitional intermediate rock. In order to disclose its geological and petrological significances, this paper carried out the LA-ICP-MS zircon U-Pb dating and geochemical investigation on both masses of Haizi diabase and granite porphyry. The results showed that the207Pb/206Pb weighted average age of granite porphyry is 1764 ± 18 Ma and diabase 1765 ± 5.4 Ma. The geochemical investigations revealed that the Haizi diabase is a kind of high-potassium alkaline basalt and the granite porphyry a kind of low-potassium rhyolite, both enriched with high field intensity elements and depleted in large-ion lithophile elements;there is obvious component intermittence between the diabase and the granite porphyry, both being bimodal and showing characteristics of continental rift valley magmatite. The?in situ?Hf isotope of dating zircon showed that mantle materials participated in the formation and emplacement of Haizi granite porphyry and crust materials participated in the formation of diabase. This meant that crustal remelting and accretion of new crust occurred in this region in the 1.7 Ga period. It can be therefore inferred that the Haizi bimodal intrusive rock came into being due to the breakup of Kunyang rift valley and rapid ascent of mantle materials in the 1.7 Ga period, which echoed the global Columbia supercontinent breakup and was the first petrological record of that breakup found at the southwest margin of Yangtze platform.展开更多
The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensi...The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensional electrical structure of the crust and upper mantle lithosphere was derived from magnetotelluric data inversion along a survey line across the central Yunnan sub-block.Results suggest that the middle and upper crust of the central Yunnan sub-block is comprised of several independent high-resistivity bodies.Deep extension of some faults was revealed according to electrical structure and relocated microseismicity.The Chenghai fault extends downward along the eastern boundary of a high-resistivity body.The Yuanmou fault dips to the west and extends to the depth along the boundary between two high-resistivity bodies.The Tanglang-Yimen fault cuts through a high-resistivity body in the middle and upper crust.There is an obvious high-conductivity C1 layer in the lower crust in the eastern part of the central Yunnan sub-block,and its western border displays an obvious structural boundary in the shallow part.The eastern part of the central Yunnan sub-block moves eastward relative to the western part(bounded by the west side of a high-resistivity body R3 in the C1 west).C1 is speculated to be characterized by low rheological strength and viscosity,thus reducing the resistance to eastward movement of the eastern part.Owing to the combined action of C1 and its western boundary,the eastern materials slip eastward faster relative to R3.Due to South China Block resistance,the middle and upper crust in the eastern part is within a compressional tectonic environment,consistent with the negative dilatation rate and the presence of compressive faults in this region.The C1 ground surface has a low strain rate,indicating weak deformation in this region and rigid motion dominance.Our results suggest that under the decoupling effect of the high-conductivity layer in the lower crust,the independent rigid blocks in the middle and upper crust can also exhibit tectonic deformation characteristics of rigid extrusion.展开更多
Based on the decoupiing theory and method, an indicator system was built for the relation between economic development level and resource and environment carrying capacity. And the study was carried out on decoupling ...Based on the decoupiing theory and method, an indicator system was built for the relation between economic development level and resource and environment carrying capacity. And the study was carried out on decoupling degree and temporal changes of economic development level and resource and environment carrying ca- pacity in the central area of Yunnan Province. Results indicated that （i） the economic development level and resource and environment carrying capacity in the central area of Yunnan Province mainly experienced strong decoupling, weak decoupling, and ex- pansive negative coupling, and in general it was strong decoupling, and it took on re- verse ＂N＂ in temporal changes. （ii） Change rate of economic development level in the central area of Yunnan Province was greater than zero, but the amplitude of change was not large, while the change rate of resource and environment carrying capacity was negative in 2007-2008, and it was positive in the rest years; from 2007, it took on gradual expansion trend, and scissors difference gradually increased after experi- encing reverse ＂V＂ change. （iii） The strong decoupling was the main situation and it reached the peak value in T5 period and T6 pedod.展开更多
The age of central Yunnan fragment uplift has long been debated, with estimates ranging from the Late Eocene to about 1 Ma. To determine the central Yunnan fragment uplift time in the Cenozoic, apatite(U-Th)/He(AHe) w...The age of central Yunnan fragment uplift has long been debated, with estimates ranging from the Late Eocene to about 1 Ma. To determine the central Yunnan fragment uplift time in the Cenozoic, apatite(U-Th)/He(AHe) was used to analyze the low-temperature thermochronology of samples from the Jiaozi Mountain area of the eastern central Yunnan fragment. The sampling area is located in the Dongchuan District of Kunming, Yunnan Province, near the Xiaojiang fault zone. The results show that AHe ages from the eastern part of central Yunnan fragment were mainly concentrated around 25.7–37.9 Ma, and intensive uplift had happened before 36.5 Ma. Together with previous low-temperature thermochronology research on the western and eastern central Yunnan fragment, we concluded that the Yunnan Plateau uplifted prior to 36.5 Ma, in a west to east sequence. The uplift caused a change in paleo-geographical terrain, which may have altered the ancient river systems of the southeast Tibetan Plateau.展开更多
Based on the NCEP reanalysis and conventional observation information,the circulation background and physical quantity field of the rare continuous intensive precipitation process occurred in autumn(from October 24 to...Based on the NCEP reanalysis and conventional observation information,the circulation background and physical quantity field of the rare continuous intensive precipitation process occurred in autumn(from October 24 to November 5) of 2008 in central section of Yunnan Province were analyzed and diagnosed.The results showed that the low-level cold front shear and mid-high level convergence zone maintenance constituted the main synoptic situation background of the rare continuous heavy rainfall in autumn in the middle regions of Yunnan Province.The two water vapor which came from the Bay of Bengal and the south of Indo-China Peninsula converged in the central and southern Yunnan,forming a deep moisture convergence zone.The warm and humid air climbed upward along the low-level cold air with the formation of a long period of upward motion,playing an important part in the maintenance of heavy precipitation weather process.The continuous heavy rainfall center and the weak high values of convective available potential energy(CAPE) had good corresponding indexicality.During the heavy precipitation,there were five mesoscale clouds which generated in the cold wind shear cloud belt.In this favorable context of large-scale circulation,frequent movement of the mesoscale system was the direct cause of this continuous intensive precipitation process.展开更多
为预防和控制引水隧洞中围岩失稳事故的发生,将物元可拓法应用于围岩稳定性评价中。以滇中引水工程为背景,选取滇中引水工程某隧洞段,构建引水隧洞围岩稳定性评价指标体系,划分围岩等级,选用灰色关联分析法(Grey Relational Analysis, G...为预防和控制引水隧洞中围岩失稳事故的发生,将物元可拓法应用于围岩稳定性评价中。以滇中引水工程为背景,选取滇中引水工程某隧洞段,构建引水隧洞围岩稳定性评价指标体系,划分围岩等级,选用灰色关联分析法(Grey Relational Analysis, GRA)和因子分析法(Factor Analysis, FA)组合确定权重,基于物元可拓模型进行引水隧洞围岩稳定性评价,以期减少目前评价方法中一些不相容现象及其他问题所带来的影响,从而提升长距离特大输水工程围岩稳定性等级评价的精度。结果表明,GRA-FA-物元可拓模型围岩稳定性评价结果与实际等级基本相符,与逼近理想解排序法(Technique for Order Preference by Similarity to Ideal Solution, TOPSIS)相比,预测评价精度从62.5%提升到87.5%,准确性提升了约25百分点。因此,GRA-FA-物元可拓模型相较以往的评价模型可以更全面和客观地进行引水隧洞围岩稳定性评价,可为其他长距离特大引水工程施工风险评价提供理论支撑。展开更多
基金supported by a key project of resources and environment of the Chinese Academy of Sciences(No:KZ951-B1-404)the Project 211 of the China University of Geosciences
文摘The Mesoproterozoic Kunyang rift, which is located on the western margin of the Yangtze platform and the southern section of the Kangdian axis, is a rare massive Precambrian iron-copper polymetallic mineralization zone in China. The Mesoproterozoic Wulu (Wuding-Lufeng) basin in the middle of the rift is an elliptic basin controlled by a ring fracture system. Moreover, volcanic activities in the basin display zonation of an outer ring, a middle ring and an inner ring with carbonatitic volcanic rocks and sub-volcanic dykes discovered in the outer and middle rings. The Sm-Nd isochron ages have been determined for the outer-ring carbonatitic lavas (1685 Ma) and basaltic porphyrite of the radiating dyke swarm (1645 Ma) and the Rb-Sr isochron ages for the out-ring carbonatitic lavas (893 Ma) and the middle-ring dykes (1048 Ma). In combination of the U-Pb concordant ages of zircon (1743 Ma) in trachy-andesite of the corresponding period and stratum (1569 Ma) of the Etouchang Formation, as well as the Rb-Sr isochron age (1024 Ma) and K-Ar age (1186 Ma) of the dykes in the middle ring, the age of carbonarites in the basin is preliminarily determined. It is ensured that all of these carbonatites were formed in the Mesoprotero/oic period, whereby two stages could be identified as follows: in the first stage, carbonatitic volcanic groups, such as lavas, pyroclastic rocks and volcaniclastic sedimentary rocks, were formed in the outer ring; in the second stage, carbonatitic breccias and dykes appeared in the middle ring. The metamorphic age of the carbonatitic lavas in the outer ring was determined to be concurrent with the end of the first stage of the Neoproterozoic period, corresponding to the Jinning movement in central Yunnan.
基金Natural Science Foundation of China(51979134,51779113)Yunnan Provincial Education Department Scientific Research Fund Project(2021J0164)+4 种基金Open Fund Project of Yunnan Provincial Key Laboratory of Highland Wetland Protection and Restoration and Ecological Services(202105AG070002)Provincial Innovation Team on Environmental Pollution and Food Safety and Human Health,Southwest Forestry University(2005AE160017)A Study of Terrestrial Animal Habitats in Li Ziping National Nature Reserve,Sichuan Province(2021ZD0125)The Construction Project of Key Disciplines with Advantages and Characteristics(Ecology)in Yunnan UniversitiesResearch Project of Key Laboratory of Soil Erosion and Control in Yunnan University。
文摘Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land,forestland,grassland,farmland,and bare land in the Dachunhe watershed of Jinning District,Kunming City,Yunnan Province,China.The effects of the soil organic carbon,total nitrogen stratification ratio,soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed.The results show that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed are statistically significant(P<0.05).The organic carbon and total nitrogen stratification ratio SR1 of garden land soil are 38.5%and 25.3%,respectively,which are higher than SR^(2).The soil organic carbon and total nitrogen stratification ratio SR^(2) of different land-use types are greater than SR1.There are statistically significant differences in the SR^(2) soil organic carbon and total nitrogen stratification ratios(P<0.05).Soil organic carbon and total nitrogen storage of diffe-rent land-use types gradually decrease with increasing soil depth,with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer.Soil organic carbon and total nitrogen sto-rage at the same soil depth are significantly different(P<0.05).Soil organic carbon and total nitrogen storage in the garden land are greater than those in the other land-use types.Soil organic carbon and total nitrogen storage in 0-20 cm garden land are 4.96 and 3.19 times than those in bare land,respectively;soil organic carbon and total nitrogen storage are explained by 93.66%and 1.53%in redundancy analysis RDA1 and RDA2,respectively.All physicochemical factors except Available Phosphorus and pH are statistically significance with carbon and nitrogen storage(P<0.05).Soil cationic exchange capacity,Available Phosphorus,C/N ratio,and Moisture Content are positively correlated with organic carbon and total nitrogen storage.In contrast,soil Bulk Density is negatively correlated with organic carbon storage and total nitrogen storage.Available Phosphorus,C/N ratio,and Moisture Content are the main factors promoting soil organic carbon and total nitrogen accumulation.
文摘This paper analyzes the necessity of mountain tourism development in central Yunnan from the aspects of market demand,rural industrial structure optimization demand,characteristic minority culture protection demand,ecological environment protection demand,beautiful rural construction demand and so on.On this basis,against the backdrop of rural revitalization strategy,the path of mountain tourism development in central Yunnan is analyzed.
基金Supported by Special Item of Public Welfare Industry,Ministry of Water Resources (201001044) Special Item of Social Undertakings Development, Yunnan Science and Technology Plan Item (2010CA013)
文摘[ Ob.jeetive] The research aimed to analyze characteristics of the meteorological drought in central Yunnan. [ Method] Based on precipi- tation data at 43 meteorological stations of the central Yunnan, SPI at year scale in each station was calculated, and occurrence frequency of the drought at different grades was conducted statistics. Finally, spline curve interpolation method was used to acquire spatial distribution characteristics of the occurrence frequencies for various-level droughts in central Yunnan. [ Result] The drought has experienced the following four stages since 1960 in central Yunnan. Firstly, SPI had obvious decrease trend, and drought had the tendency to become severe in the 1970s. Secondly, in the 1960s and the 1980s, although variation of the SPI was large, we didn＇t find any distinct changing trend. Thirdly, SPI showed an evident increasing trend from the late 1980s to 2000. That was to say, central Yunnan experienced a wet period within those years. Lastly, the drought became severe from 2001 to 2009. Honghe, Yuanjiang, Binchuan, Luquan and Zhanyi tended to suffer from the medium drought; Kunming, Chenggong, Qujing, northeast Chuxiong, Dali, east Yangbi and central Yuxi tended to suffer from the severe drought; Zhanyi, Binchuan, west Dayao, Xiangyun, north Qujing, Anning and northwest Kunming tended to suffer from the extreme drought. [ Conclusion] The research provided theoreticai basis for drought prevention and control in the zone.
文摘The Haizi diabase-granite porphyry composite rock mass is located in the Wuding-Yanjing taphrogenic trough within the Paleoproterozoic Kangdian fault-uplift zone. According to field observations, the diabase is divided into two types: central facies and marginal facies;the granite porphyry directly contacts the central facies of diabase without transitional intermediate rock. In order to disclose its geological and petrological significances, this paper carried out the LA-ICP-MS zircon U-Pb dating and geochemical investigation on both masses of Haizi diabase and granite porphyry. The results showed that the207Pb/206Pb weighted average age of granite porphyry is 1764 ± 18 Ma and diabase 1765 ± 5.4 Ma. The geochemical investigations revealed that the Haizi diabase is a kind of high-potassium alkaline basalt and the granite porphyry a kind of low-potassium rhyolite, both enriched with high field intensity elements and depleted in large-ion lithophile elements;there is obvious component intermittence between the diabase and the granite porphyry, both being bimodal and showing characteristics of continental rift valley magmatite. The?in situ?Hf isotope of dating zircon showed that mantle materials participated in the formation and emplacement of Haizi granite porphyry and crust materials participated in the formation of diabase. This meant that crustal remelting and accretion of new crust occurred in this region in the 1.7 Ga period. It can be therefore inferred that the Haizi bimodal intrusive rock came into being due to the breakup of Kunyang rift valley and rapid ascent of mantle materials in the 1.7 Ga period, which echoed the global Columbia supercontinent breakup and was the first petrological record of that breakup found at the southwest margin of Yangtze platform.
基金supported by the Basic Research Project of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.2020IEF0505)the Basic Research Project of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.2021IEF0104)the National Natural Science Foundation of China(Grant Nos.U1839205&42174093)。
文摘The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensional electrical structure of the crust and upper mantle lithosphere was derived from magnetotelluric data inversion along a survey line across the central Yunnan sub-block.Results suggest that the middle and upper crust of the central Yunnan sub-block is comprised of several independent high-resistivity bodies.Deep extension of some faults was revealed according to electrical structure and relocated microseismicity.The Chenghai fault extends downward along the eastern boundary of a high-resistivity body.The Yuanmou fault dips to the west and extends to the depth along the boundary between two high-resistivity bodies.The Tanglang-Yimen fault cuts through a high-resistivity body in the middle and upper crust.There is an obvious high-conductivity C1 layer in the lower crust in the eastern part of the central Yunnan sub-block,and its western border displays an obvious structural boundary in the shallow part.The eastern part of the central Yunnan sub-block moves eastward relative to the western part(bounded by the west side of a high-resistivity body R3 in the C1 west).C1 is speculated to be characterized by low rheological strength and viscosity,thus reducing the resistance to eastward movement of the eastern part.Owing to the combined action of C1 and its western boundary,the eastern materials slip eastward faster relative to R3.Due to South China Block resistance,the middle and upper crust in the eastern part is within a compressional tectonic environment,consistent with the negative dilatation rate and the presence of compressive faults in this region.The C1 ground surface has a low strain rate,indicating weak deformation in this region and rigid motion dominance.Our results suggest that under the decoupling effect of the high-conductivity layer in the lower crust,the independent rigid blocks in the middle and upper crust can also exhibit tectonic deformation characteristics of rigid extrusion.
基金Supported by Scientific Research Foundation of Yunnan Provincial Department of Education(2015J088)~~
文摘Based on the decoupiing theory and method, an indicator system was built for the relation between economic development level and resource and environment carrying capacity. And the study was carried out on decoupling degree and temporal changes of economic development level and resource and environment carrying ca- pacity in the central area of Yunnan Province. Results indicated that （i） the economic development level and resource and environment carrying capacity in the central area of Yunnan Province mainly experienced strong decoupling, weak decoupling, and ex- pansive negative coupling, and in general it was strong decoupling, and it took on re- verse ＂N＂ in temporal changes. （ii） Change rate of economic development level in the central area of Yunnan Province was greater than zero, but the amplitude of change was not large, while the change rate of resource and environment carrying capacity was negative in 2007-2008, and it was positive in the rest years; from 2007, it took on gradual expansion trend, and scissors difference gradually increased after experi- encing reverse ＂V＂ change. （iii） The strong decoupling was the main situation and it reached the peak value in T5 period and T6 pedod.
基金supported by the National Natural Science Foundation of China (Nos. 41802215,41762017)。
文摘The age of central Yunnan fragment uplift has long been debated, with estimates ranging from the Late Eocene to about 1 Ma. To determine the central Yunnan fragment uplift time in the Cenozoic, apatite(U-Th)/He(AHe) was used to analyze the low-temperature thermochronology of samples from the Jiaozi Mountain area of the eastern central Yunnan fragment. The sampling area is located in the Dongchuan District of Kunming, Yunnan Province, near the Xiaojiang fault zone. The results show that AHe ages from the eastern part of central Yunnan fragment were mainly concentrated around 25.7–37.9 Ma, and intensive uplift had happened before 36.5 Ma. Together with previous low-temperature thermochronology research on the western and eastern central Yunnan fragment, we concluded that the Yunnan Plateau uplifted prior to 36.5 Ma, in a west to east sequence. The uplift caused a change in paleo-geographical terrain, which may have altered the ancient river systems of the southeast Tibetan Plateau.
基金Supported by Regional Fund Program of Natural Science Foundation of China(NSFC)(40965002)Natural Science Foundation of Yun-nan Province(2005D0078M2)
文摘Based on the NCEP reanalysis and conventional observation information,the circulation background and physical quantity field of the rare continuous intensive precipitation process occurred in autumn(from October 24 to November 5) of 2008 in central section of Yunnan Province were analyzed and diagnosed.The results showed that the low-level cold front shear and mid-high level convergence zone maintenance constituted the main synoptic situation background of the rare continuous heavy rainfall in autumn in the middle regions of Yunnan Province.The two water vapor which came from the Bay of Bengal and the south of Indo-China Peninsula converged in the central and southern Yunnan,forming a deep moisture convergence zone.The warm and humid air climbed upward along the low-level cold air with the formation of a long period of upward motion,playing an important part in the maintenance of heavy precipitation weather process.The continuous heavy rainfall center and the weak high values of convective available potential energy(CAPE) had good corresponding indexicality.During the heavy precipitation,there were five mesoscale clouds which generated in the cold wind shear cloud belt.In this favorable context of large-scale circulation,frequent movement of the mesoscale system was the direct cause of this continuous intensive precipitation process.
文摘为预防和控制引水隧洞中围岩失稳事故的发生,将物元可拓法应用于围岩稳定性评价中。以滇中引水工程为背景,选取滇中引水工程某隧洞段,构建引水隧洞围岩稳定性评价指标体系,划分围岩等级,选用灰色关联分析法(Grey Relational Analysis, GRA)和因子分析法(Factor Analysis, FA)组合确定权重,基于物元可拓模型进行引水隧洞围岩稳定性评价,以期减少目前评价方法中一些不相容现象及其他问题所带来的影响,从而提升长距离特大输水工程围岩稳定性等级评价的精度。结果表明,GRA-FA-物元可拓模型围岩稳定性评价结果与实际等级基本相符,与逼近理想解排序法(Technique for Order Preference by Similarity to Ideal Solution, TOPSIS)相比,预测评价精度从62.5%提升到87.5%,准确性提升了约25百分点。因此,GRA-FA-物元可拓模型相较以往的评价模型可以更全面和客观地进行引水隧洞围岩稳定性评价,可为其他长距离特大引水工程施工风险评价提供理论支撑。
