期刊文献+
共找到1,779篇文章
< 1 2 89 >
每页显示 20 50 100
Mapping Spatial and Temporal Variations of Leaf Area Index for Winter Wheat in North China 被引量:13
1
作者 YANG Peng WU Wen-bin +3 位作者 TANG Hua-jun ZHOU Qing-bo ZOU Jin-qiu ZHANG Li 《Agricultural Sciences in China》 CAS CSCD 2007年第12期1437-1443,共7页
Leaf area index (LAI) is an important parameter in a number of models related to ecosystem functioning, carbon budgets, climate, hydrology, and crop growth simulation. Mapping and monitoring the spatial and temporal... Leaf area index (LAI) is an important parameter in a number of models related to ecosystem functioning, carbon budgets, climate, hydrology, and crop growth simulation. Mapping and monitoring the spatial and temporal variations of LAI are necessary for understanding crop growth and development at regional level. In this study, the relationships between LAI of winter wheat and Landsat TM spectral vegetation indices (SVIs) were analyzed by using the curve estimation procedure in North China Plain. The series of LAI maps retrieved by the best regression model were used to assess the spatial and temporal variations of winter wheat LAI. The results indicated that the general relationships between LAI and SVIs were curvilinear, and that the exponential model gave a better fit than the linear model or other nonlinear models for most SVIs. The best regression model was constructed using an exponential model between surface-reflectance-derived difference vegetation index (DVI) and LAI, with the adjusted R2 (0.82) and the RMSE (0.77). The TM LAI maps retrieved from DVILAI model showed the significant spatial and temporal variations. The mean TM LAI value (30 m) for winter wheat of the study area increased from 1.29 (March 7, 2004) to 3.43 (April 8, 2004), with standard deviations of 0.22 and 1.17, respectively. In conclusion, spectral vegetation indices from multi-temporal Landsat TM images can be used to produce fine-resolution LAI maps for winter wheat in North China Plain. 展开更多
关键词 leaf area index (LAI) winter wheat spectral vegetation index (SVI) Landsat TM north China Plain
下载PDF
Street Space in Traditional Settlements in Mountainous Area of North China 被引量:2
2
作者 彭鹏 刘丽 《Journal of Landscape Research》 2010年第11期1-5,共5页
With mountainous area of North China as the research objective,the study analyzed street space in traditional settlements in mountainous area of North China from the perspective of form,structure and culture,hoping to... With mountainous area of North China as the research objective,the study analyzed street space in traditional settlements in mountainous area of North China from the perspective of form,structure and culture,hoping to find some methods and laws that could be served as the reference for the design of living environment in future. 展开更多
关键词 Mountainous area of north China TRADITIONAL SETTLEMENTS STREET SPACE
下载PDF
Interdecadal and decadal variation of temperature over North Pole area and the relation with solar activity 被引量:1
3
作者 QU Weizheng ZHAO Jinping DU Ling HUANG Fei FAN Tingting 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第2期53-61,共9页
Obvious tendency and periodicity of the air temperature can be detected over the North Pole area.They are reflected as follows: a.the air temperature at the earth surface and in the middle layer of the stratosphere t... Obvious tendency and periodicity of the air temperature can be detected over the North Pole area.They are reflected as follows: a.the air temperature at the earth surface and in the middle layer of the stratosphere tends to be increased either in winter or in summer.The air temperature has increased 1.3 °C for about 50 years at a speed about 0.025 °C/year in January,and 0.013 °C/year in July.The air temperature in the middle layer of the stratosphere (10 hPa) in January has increased 10 °C.The temperature rising speed in July is 0.14 °C/year.Generally speaking,the temperature rising speed is quicker in winter than in summer and quicker in the upper layer than at the earth surface.b.The air temperature at the top layer of the troposphere (100 hPa) over the North Pole area tends to be increased either in winter or in summer.The air temperature in January has decreased 5.0 °C for about 50 years at a temperature decreasing speed about 0.094 °C/year,and at a temperature decreasing speed about 0.032 °C/year in July.The speed of the temperature decreasing is greater in winter than in summer.c.Periodicity.The air temperature respectively at different altitudes over the North Pole possesses interdecadal variation with a period of 22 years.In July the amplitude of the variation with a period of 22 years decreases rapidly from the high altitude to the low.This means that the 22–year’s period is more obvious at the high altitude than at the low altitude.At the earth surface layer in North Pole there also is obvious decadal variation with a period of 11 years.The analysis indicates that the 22-years’ period temperature variation is associated with the periodic variation of the solar magnetic field.The 11-year period temperature variation is corresponding to 11 year’ period of the variation of the sunspot number. 展开更多
关键词 decadal variation of air temperature solar activity north Pole area
下载PDF
Hydrogeochemical characteristics of groundwater and pore-water and the paleoenvironmental evolution in the past 3.10 Ma in the Xiong’an New Area,North China 被引量:3
4
作者 Kai Zhao Jing-xian Qi +6 位作者 Yi Chen Bai-heng Ma Li Yi Hua-ming Guo Xin-zhou Wang Lin-ying Wang Hai-tao Li 《China Geology》 2021年第3期476-486,共11页
The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area,North China,which caused the enhanced mixing of groundwater in different aquifers a... The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area,North China,which caused the enhanced mixing of groundwater in different aquifers and significant changes in regional groundwater chemistry characteristics.In this study,groundwater and sediment pore-water in drilling cores obtained from a 600 m borehole were investigated to evaluate hydrogeochemical processes in shallow and deep aquifers and paleo-environmental evolution in the past ca.3.10 Ma.Results showed that there was no obvious change overall in chemical composition along the direction of groundwater runoff,but different hydrochemical processes occurred in shallow and deep groundwater in the vertical direction.Shallow groundwater(<150 m)in the Xiong’an New Area was characterized by high salinity(TDS>1000 mg/L)and high concentrations of Mn and Fe,while deep groundwater had better water quality with lower salinity.The high TDS values mostly occurred in aquifers with depth<70 m and>500 m below land surface.Water isotopes showed that aquifer pore-water mostly originated from meteoric water under the influence of evaporation,and aquitard pore-water belonged to Paleo meteoric water.In addition,the evolution of the paleoclimate since 3.10 Ma BP was reconstructed,and four climate periods were determined by theδ18O profiles of pore-water and sporopollen records from sediments at different depths.It can be inferred that the Quaternary Pleistocene(0.78‒2.58 Ma BP)was dominated by the cold and dry climate of the glacial period,with three interglacial intervals of warm and humid climate.What’s more,this study demonstrates the possibilities of the applications of pore-water on the hydrogeochemical study and further supports the finding that pore-water could retain the feature of paleo-sedimentary water. 展开更多
关键词 GROUNDWATER PORE-WATER HYDROGEOCHEMISTRY Stable oxygen isotope Paleoclimate change Paleoenvironmental reconstruction Hydrogeological survey engineering Xiong’an New area north China
下载PDF
Genetic Relationship of the 1780-1760 Ma Dykes and the Coeval Volcanics in the Lvliang Area, North China 被引量:1
5
作者 YANG Shuyan PENG Peng +2 位作者 Qin Zhaoyuan WANG Xinping WANG Chong 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期133-134,共2页
The 1780-1760 Ma Taihang dyke swarm and the coeval Xiong’er volcanic province are the most widespread magmatic events occurring post the amalgamation of the two North China cratons.It has been debated whether
关键词 north China Genetic Relationship of the 1780-1760 Ma Dykes and the Coeval Volcanics in the Lvliang area PB
下载PDF
The Source of Groundwater Recharge Based on Entropy Theory in the Arid Areas of North China 被引量:1
6
作者 CHEN Jiansheng XU Yi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第1期390-391,共2页
Objective Any natural system is constantly exchanging material, energy and information with the environment, and all tkese processes follow the basic law of thermodynamics, with no exception of groundwater recharge a... Objective Any natural system is constantly exchanging material, energy and information with the environment, and all tkese processes follow the basic law of thermodynamics, with no exception of groundwater recharge and discharge process. On the basis of the principle of the first law of thermodynamics, the reverse geochemical simulation method is widely used in the study of groundwater recharge, runoff and drainage process. However, some studies only consider the material conservation in theprocess, but ignore the probability of the transformation. 展开更多
关键词 The Source of Groundwater Recharge Based on Entropy Theory in the Arid areas of north China
下载PDF
THE POSSIBILITIES AND REALITIES ON THE REMANAGEMENT OF DESERTIFIED LANDS IN THE TRANSITIONAL ZONE BETWEEN THE DRY-FARMING AREA AND THE GRAZING AREA IN NORTH CHINA
7
作者 朱震达 刘恕 杨有林 《Chinese Geographical Science》 SCIE CSCD 1991年第1期32-43,共12页
The desertification process is rapidly developing at present and 61.5% of the land area in the zone are already desertified.Among the desertified lands, 26.9% are seriously desertified, 25% most seriously desertified ... The desertification process is rapidly developing at present and 61.5% of the land area in the zone are already desertified.Among the desertified lands, 26.9% are seriously desertified, 25% most seriously desertified and 47.4% are the lands where desertification is under way. They are caused by over-reclamation for farming, over-grazing, unreasonable collection of firewood,the destruction of vegetation and the misuse of water resources. Under the ecological environment in semi-arid zone,the degraded environment process possesses the ability of restoring to its original status as soon as the interruption of excessive human activities are eliminated. The fencing- and-self-cultivating method is an effective measure adopted universally in semi-arid zone to cure the desertified lands.The desertified lands can be readjusted and controlled easily if other controlling measures are supplemented. The fundamental ways to control desertification are to utilize rationally the resources, to readjust the existing 展开更多
关键词 desertified lands the transitional zone BETWEEN the dry-larming area and the GRAZING area remanagement north China.
下载PDF
ANALYSIS OF FOLDS SOUTH OF MALAKAND AND ADJOINING AREAS, NORTH PAKISTAN
8
作者 Irshad Ahmad 1,Joseph A. DiPietro 2(1.NCE in Geology, University of Peshawar Pakistan 2.Department of Geology, University of Southern Indiana, Evansville,IN 47712,USA) 《地学前缘》 EI CAS CSCD 2000年第S1期69-70,共2页
North of the study area in lower Swat, the rocks have been found to have undergone multiple deformations with at least four periods of folding during a single Paleogene metamorphism (DiPietro and Lawrence, 1991). The ... North of the study area in lower Swat, the rocks have been found to have undergone multiple deformations with at least four periods of folding during a single Paleogene metamorphism (DiPietro and Lawrence, 1991). The earliest folds are composite W—SW vergent, syn\|metamorphic F 1/F 2 folds associated with the formation of the regional foliation. Late\|metamorphic, N—S trending open upright F 3 folds are associated with local foliation development, and E—W trending open F 4 folds are associated with retrograde metamorphism. These interfere with each other to produce dome/basin structures. 展开更多
关键词 PALEOGENE METAMORPHISM the regional FOLIATION Malakand and adjoining areas north Pakistan
下载PDF
Discussion on the dynamic mechanism of Great North China area based on the observed stress data
9
作者 冯向东 魏东平 陈棋福 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2005年第1期1-11,124,共12页
Based on the constrained data from the observed stress orientation and the observed stress regime, the tectonic stress fields of the Great North China area has been simulated by using the pseudo-3D finite element meth... Based on the constrained data from the observed stress orientation and the observed stress regime, the tectonic stress fields of the Great North China area has been simulated by using the pseudo-3D finite element method. The results indicate that the stress fields in this area are basically controlled by the push forces coming from the Pacific Plate and from the Tibet Plateau, and the WNW-ward action from the Pacific Plate play a more important role in North China plain block. In addition to that, the stress field in this area is also partly formed by the extension action from the mantle upwelling in perpendicular at the basin margins. 展开更多
关键词 Great north China area stress regime finite element method dynamic simulation
下载PDF
Analysis on Variations of the Temperature and Precipitation in North Slope Area of the Western Tianshan in Recent 50 Years
10
作者 YAO Fu-long,LI Hai-bing College of Chemistry and Biological Sciences,Yili Normal University,Yining 835000,China 《Meteorological and Environmental Research》 CAS 2011年第11期17-22,共6页
[Objective] The research aimed to analyze variation characteristics of the temperature and precipitation in north slope area of the Western Tianshan in recent 50 years.[Method] According to temperature and rainfall da... [Objective] The research aimed to analyze variation characteristics of the temperature and precipitation in north slope area of the Western Tianshan in recent 50 years.[Method] According to temperature and rainfall data from 1961 to 2010 at three meteorological stations in north slope area of the Western Tianshan,climate change in the zone in recent 50 years was analyzed by using linear trend analysis method and 5-year sliding average method.[Result] The temperature in north slope area of the Western Tianshan showed significant warming trend.The annual average temperature significantly increased at 0.3 ℃/10 a in recent 50 years.But rise rates of the temperature in different seasons were different:autumn> winter> spring> summer.The annual rainfall in north slope area of the Western Tianshan in recent 50 years overall presented relative increase trend.Seen from annual rainfall,it significantly increased at 16.9 mm/10 a.Seen from seasonal rainfall,except in autumn,rainfalls in other three seasons in the past 50 years all showed significant increase trends,with amplitude of 3.2-11.2 mm/10 a.The largest increase amplitude was in summer.After a small precipitation peak in the 1980s,autumn rainfall slightly declined in the past 20 years.[Conclusion] The climate in north slope area of the Western Tianshan become warm and wet. 展开更多
关键词 Climate change TEMPERATURE PRECIPITATION north slope area of the Western Tianshan China
下载PDF
Slope runoff study in situ using rainfall simulator in mountainous area of North China
11
作者 于静洁 杨聪 +4 位作者 刘昌明 宋献方 胡珊珊 李发东 唐常源 《Journal of Geographical Sciences》 SCIE CSCD 2009年第4期461-470,共10页
Simulated rainfall is a valid tool to examine the runoff generation on the slope.13 simulated rainfall experiments with different rainfall intensities and durations are completed in a 5 m ×10 m experimental plot ... Simulated rainfall is a valid tool to examine the runoff generation on the slope.13 simulated rainfall experiments with different rainfall intensities and durations are completed in a 5 m ×10 m experimental plot in mountainous area of North China.Simultaneously,rainfall,surface runoff,soil-layer flow,mantel-layer flow and soil moisture are monitored respectively.From the results,it is found that the hydrographs in all layers have the characteristics of rapid rise and fall.The recessions of surface flow and soil-layer flow are much faster than that of mantel-layer flow.Surface flow,the main contributor,makes up more than 60% of the total runoff in the study area.It even exceeds 90% in the cases of high intensity rainfall events.Runoff coefficient(ratio of total runoff to rainfall amount) is mainly influenced by rainfall amount,rainfall intensity and antecedent soil moisture,and the relationship can be well expressed by a multiple linear regression function α = 0.002P + 0.182i + 4.88Wa-0.821.The relation between the rainfall intensity and the lag time of three flows(surface runoff,soil-layer flow and mantel-layer flow) is shown to be exponential.Then,the result also shows that the recession constant is 0.75 for surface runoff,is 0.94 for soil-layer and mantel-layer flow in this area.In this study area,the dominant infiltration excess runoff is simulated by Horton model.About 0.10 mm/min percolation is observed under the condition of different rainfall intensities,therefore the value is regarded as the steady infiltration rate of the study area. 展开更多
关键词 simulated rainfall slope plot runoff generation process mountainous area of north China
下载PDF
Hydrographic structure and circulation in the central area of the North Eastern Atlantic
12
作者 Xu Jianping Second Institute of Oceanography, State Oceanic Administration, P. O. Box 1207, Hangzhou 310012, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第3期343-356,共14页
-On the basis of the hydrographic data observed within the Canary Basin in autumn 1985, temperature-salinity properties, distributions of water masses and barocltne flow field, as well as the volume transports in this... -On the basis of the hydrographic data observed within the Canary Basin in autumn 1985, temperature-salinity properties, distributions of water masses and barocltne flow field, as well as the volume transports in this area are described more detailly. The analyses indicate that the activity in the waters of the Canary Basin is mainly attributed to the interleaving and mixing between the originated water masses (e. g. Surface Water, North Atlantic Central Water, Mediterranean Water and Deep Water) and the modified water masses (Subpolar Mode Water, Labrador Sea Water and Antarctic Intermediate Water) from the outside of the study area and the variation of themselves. The east recirculation of the Subtropic Gyre in the North Atlantic consists of Azores Current and Canary Current.Azores Current is formed with several flow branches around the Azores Island, while the main flow lies at 35?N south of the Azores Island. It begins to diverge near the 15?W. The return flow found off the Portugal coast may be its northern branch. The southern invasion of the Labrador Sea Water and the Subpolar Mode Water are prevented by Azores front which serves an obvious boundary separating the North Western Atlantic (Central) Water and the North Eastern Atlantic (Central) Water. 展开更多
关键词 Hydrographic structure and circulation in the central area of the north Eastern Atlantic area
下载PDF
The Finding and Phylogenetic Evolution Analysis of Bovine Piroplasms in the Rasǒn Area of North Korea
13
作者 JIA Li-jun ZHANG Shou-fa +3 位作者 CAO Shi-nuo QIAN Nian-chao YU Long-zheng XUAN Xue-nan 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2013年第10期1847-1854,共8页
The objective of this study was to investigate the epidemiology of bovine Piroplasms infections in the Rasǒn area of North Korea.The survey was carried out by light microscopic examination of Giemsa-stained blood sme... The objective of this study was to investigate the epidemiology of bovine Piroplasms infections in the Rasǒn area of North Korea.The survey was carried out by light microscopic examination of Giemsa-stained blood smears,PCR,and phylogenetic evolution analysis of 128 blood samples collected from the Rasǒn area.The results showed that the infection rates of the small and large parasites were about 2.5 and 1.5% on average,respectively,in all Theileria sergenti and Babesia ovatapositive blood smears by microscopic examination of blood smears.The detection rate of T.sergenti Giemsa-stained smears was 43.75%,while that with PCR was 67.97%.The detection rate of B.ovata Giemsa-stained smears was 49.21%,while that with PCR was 71.88%.The sequence and phylogenetic analysis of DNA showed 98.84% homology between the 18S rRNA gene sequences of T.sergenti isolates from North Korean and that of Yanbian state from China,indicating the closest genetic relationship between both of them.Moreover,100% homology was shown between the 18S rRNA gene sequence of B.ovata isolates from North Korea and the published sequence AY081192 of GenBank,indicating the closest genetic relationship between both of them.This survey confirmed that Ras n is the endemic area of T.sergenti and B.ovata in North Korea. 展开更多
关键词 Rasǒn area of north Korea bovine Piroplasms phylogenetic trees
下载PDF
Contribution to the hydrogeologic setting of Baghdad area(south EL Arish,north Sinai)based on geoelectrical study
14
《Global Geology》 1998年第1期117-117,共1页
关键词 EL Contribution to the hydrogeologic setting of Baghdad area south EL Arish north Sinai)based on geoelectrical study
下载PDF
Characteristics of Nitrogen and Phosphorus Losses in Different Crop Rotation Systems in the North of Erhai Lake Basin 被引量:8
15
作者 汤秋香 任天志 +5 位作者 雷宝坤 翟丽梅 胡万里 张继宗 林涛 刘宏斌 《Agricultural Science & Technology》 CAS 2012年第10期2206-2212,共7页
[Objective] Nitrogen and phosphorus losses of surface runoff in various crop rotation systems in the north of Erhai Lake basin were studied with the objective to provide references for risk evaluation of environmental... [Objective] Nitrogen and phosphorus losses of surface runoff in various crop rotation systems in the north of Erhai Lake basin were studied with the objective to provide references for risk evaluation of environmental pollution and formulating countermeasures to control the nonpoint source pollution from agriculture.[Method] Water samples collected in four typical crop rotation systems distributed in seven towns(townships) in the north of Erhai Lake basin were investigated,as well as the fertilizer input,to explore the dynamic change of nitrogen and phosphorus content in surface water of farmland and ditch water,and the correlation between fertilizer input and the concentrations of nitrogen and phosphorus in the surface water of farmland and in the ditch water.[Result] The results showed that nitrogen loss in surface water of farmland in different crop rotation systems differed greatly,and the risk of nitrogen loss was 38% lower in broad bean-rice crop rotation than that in garlic-rice crop rotation.The water soluble nitrogen was the primary form of nitrogen loss.The content of water soluble nitrogen was significantly higher in garlic-rice crop rotation than that in the other rotation systems,and the concentrations of nitrogen in the surface water of farmland in different crop rotation systems followed the sequence below:garlic-rice crop rotationryegrass-rice crop rotationbroad bean-rice crop rotationrape-rice crop rotation.The loss of phosphorus in the surface water of farmland was relatively low and phosphorus combined with silt was the primary form for phosphorus loss.There was no significant difference of the loss of various forms of phosphorus in different crop rotation systems.The contents of total nitrogen and total phosphorus in the surface water of farmland were higher than that in ditch water,with increasing rates of total nitrogen and total phosphorus in ditch water of 72% and 82%,respectively.Topdressing was the critical reason for the high concentrations of nitrogen and phosphorus in the surface water,which also caused the increasing load to the ditch water.[Conclusion] Both the nitrogen and phosphorus loss were the highest in garlic-rice crop rotation.Reasonable crop rotation systems should be established based on both the environmental and economic benefits.This study provided references for controlling the nonpoint source pollution of farmland and improving the water quality of Erhai Lake. 展开更多
关键词 The northe areas of Erhai Lake basin FARMLAND Crop rotation Nitrogen and phosphorus losses
下载PDF
Huanggang Intrusive Complexin Northern Tongbai Area:Island-Arc Tectonic Environment and Its Geological Significance 被引量:3
16
作者 Zhang Li Zhang Hongfei Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1998年第3期37-41,共5页
The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex be... The Huanggang intrusive complex in northern Tongbai area was formed in Early Paleozoic. It mainly consists of ultra basic, basic, intermediate and acid rocks, dominated by intermediate and basic rocks. The complex belongs to calc alkaline series. Geochemical characteristics of major and trace elements show that the complex was derived from the fractional crystallization of co source magma. It is suggested that the complex was formed in island arc tectonic environment and was closely related to the northward subduction of the Erlangping back arc basin. Thus, the subduction of the back arc basin can induce the island arc type magmatism similar to the one formed in the setting of ocean plate subduction. 展开更多
关键词 Huanggang intrusive complex island arc tectonic environment geochemistry northern Tongbai area north Qinling.
下载PDF
Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements 被引量:2
17
作者 杨国华 韩月萍 张凤兰 《Acta Seismologica Sinica(English Edition)》 CSCD 2001年第1期1-11,共11页
Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished... Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished, 4 active units and 1 transition zone with distinct differential movement have been determined. They are Ordos-Yinshan unit, Yanshan unit, Shanxi-Hebei-Shandong (Jin-Ji-Lu) unit, Jiaodong-Liaoning-Shandong (Jiao-Liao-Lu) unit and Yanshan-Hebei (Yan-Ji) transition zone. The relative movements among the neighboring units in this period have been given. ① The compressive movement between Ordos-Yinshan unit and Yanshan unit is not obvious with an amount of 0.4(1.3 mm/a.②in-Ji-Lu unit moves E40(S off the Ordos-Yinshan unit and the magnitude is 4.4(1.0 mm/a. ③elative to the Yan-Ji transition zone of differential movement, Yanshan unit shifts W38(N with a value of 2.4(1.3 mm/a and Jin-Ji-Lu unit moves eastward 35( by south with an amount of 2.3(0.9 mm/a. ④Jin-Ji-Lu unit has a tensional left-lateral movement of 4.7(1.4 mm/a in the direction of E37(S relative to Yanshan unit. ⑤ Some area near Tanlu belt which is located in the southern part of Jin-Ji-Lu block has a southward movement 14( by west with a magnitude of 1.5(1.1 mm/a off the Jin-Ji-Lu unit. ⑥ Relative to Jin-Ji-Lu unit, Jiao-Liao-Lu unit has a trend of clockwise movement with a tensional right-lateral motion at the north end which neighbors Yanshan unit and a compressive motion at the south end. It should be noted that the errors given in the paper are obtained based on the divergence among the displacements of the sites in the unit, rather than the value calculated from the displacement error of the sites. The analyzed results indicate that: ① Shanxi tectonic zone and Yan-Ji transition zone are the major tectonic active zones to show the frame and magnitude of interior relative movement in North China area, and others are the secondary tectonic active zones; ② The complete horizontal deformation in the North China area is not homogeneous nor successive; ③ The kinetic model of North China area might be (mantle dragging plus boundary coupling(. 展开更多
关键词 GPS measurement north China area active unit horizontal movement deformation mechanism
下载PDF
Analysis of Two Hailstorm Processes Accompanied with Weak Precipitation in the North of Shandong 被引量:1
18
作者 Zheng Lina Zhang Zihan Jia Xiaoqin 《Meteorological and Environmental Research》 CAS 2017年第6期6-14,共9页
Based on conventional observation data,wind profile radar data and data obtained by a microwave radiometer,the formation mechanisms of two hailstorm processes accompanied with weak precipitation in the north of Shando... Based on conventional observation data,wind profile radar data and data obtained by a microwave radiometer,the formation mechanisms of two hailstorm processes accompanied with weak precipitation in the north of Shandong Province on June 8 and July 1 in 2014 were analyzed. The results showed that energy accumulated before the occurrence of two hailstorm processes. That is,the height of 0 ℃ and-20 ℃ layer dropped rapidly in the period of hailing,and the height of 0 ℃ layer was around 2. 2 km. Echo clusters producing hail still belonged to meso-γ scale-meso-β scale,and the intensity of reflectivity factor exceeded 50 dBz; echo top was at 12-14 km,and vertically integrated liquid water content was over 30 kg/m^2; in the two processes,water accumulation zones were distributed at 0. 6-2. 0 km. In addition,the water vapor conditions of low-level environmental fields were poor,which resulted in small rainfall in the two processes. However,there were significant differences between the two processes in terms of influencing systems,motion path of hail,changes of ground meteorological elements and disasters. The influencing systems of the " 608" process were the cold vortex,transverse trough and cold front. Convective clouds moved from the northwest to the southeast,and ground temperature dropped,while dew point and ground pressure rose; wind direction changed suddenly with the movement of cold front,and there was no disaster. The influencing systems of the " 701" process were the upper trough,shear line and convergence line. Convective clouds moved from the south to the north. When convective clouds moved to the station,ground temperature dropped,and there was no obvious change in dew point; ground pressure declined sharply,and wind speed was small,but wind direction was changeable,so that the local direct economic loss was up to about 0. 2 billion yuan. 展开更多
关键词 HAIL Influencing systems Water ACCUMULATION areas The north of SHANDONG
下载PDF
Earthquake-controlling Processes of Detachment Zones in Eastern North China 被引量:1
19
作者 SUNAiqun NIUShuyin +2 位作者 SHAOJi'an HOUQuanlin ZHANGJianzhen 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第1期283-290,共8页
The basin-and-range area in eastern North China is known for frequent occurrence of earthquakes, their great magnitudes and heavy losses thereby incurred. Seismic studies in the past usually emphasized the intersectio... The basin-and-range area in eastern North China is known for frequent occurrence of earthquakes, their great magnitudes and heavy losses thereby incurred. Seismic studies in the past usually emphasized the intersections, inflexions and branches of the faults. However, the intensities of many great earthquakes in this area do not show linear distribution, and the epicenters are horizontally dispersed at certain depths instead of along the strike of faults. Based on the sub-mantle plume studies made by authors in the past decade, it is thought that there exists an uplifted sub-mantle plume under the fault depression area in North China. The uplifting and intrusion of mantle materials caused the upper crust to be faulted, while low-velocity and high-velocity layers are alternatively distributed in the middle crust under the influence of the mantle and the lower crust. The middle and lower crust materials were detached from the top of the sub-mantle plume to the surroundings while the sub-mantle plume materials were detached outward. When the detached middle and lower crust come to the boundary of fault basins in the upper crust, they will be obstructed by the orogenic zone and the detachment will go slower. The shearing between them will cause the stress to accumulate and release alternatively, so that earthquakes occurred frequently in the areas of sub-mantle plume and its surroundings. 展开更多
关键词 sub-mantle plume detachment belt earthquake-controlling structure low-velocity and high-conductivity zones north China basin-and range area
下载PDF
RESPONSE OF TRIASSIC SEQUENCE STRATIGRAPHY OF LOWER YANGTZE TO THE COLLISION BETWEEN THE YANGTZE PLATE AND THE NORTH CHINA PLATE 被引量:1
20
作者 CHENG Rihui WANG Pujun LIU Wanzhu TANG Huafeng BAI Yunfeng KONG Qingying SONG Weihai 《Geotectonica et Metallogenia》 2005年第2期174-184,共11页
The characteristics of the Triassic sequences developed in the Lower Yangtze area display some great changes in both environment and climate. The change of environment was a transition from marine to continent via alt... The characteristics of the Triassic sequences developed in the Lower Yangtze area display some great changes in both environment and climate. The change of environment was a transition from marine to continent via alternating environments. The change of climate was a transition from tropic (torrid) to warm and wet climate via subtropic dry climate. The type variations of the sequences were from the marine sequences to the continental sequences, corresponding to the changes of environments and climates. Sequence 1 is a type II of sequence of mixed elastic and carbonate sediments; sequence 2 is a type I of sequence of carbonate platform; sequence 3 is a type I of sequence of carbonate tidal flat-salt lagoon, sequence 4 is a type iI of sequence of lacustrine within marine layers, and sequence 5 is a sequence of lacustrine-swamp. The development, distribution and preservation of those sequences reveal the tectonic controls and their changes in the background. The collision between the Yangtze plate and the North China plate was a great geological event in the geological history, but the timing of the collision is still disputed. However, the characteristics of Triassic sequence stratigraphy and sea level changes in the Lower Yangtze area responded to this collision. The collision started at the beginning of middle Triassic and the great regression in the Lower Yangtze area started 22Ma earlier than those in the world. The tectonic conditions occurred before and during the collision controlled the development of sequences and type changes. 展开更多
关键词 Yangtze plate north China plate Lower Yangtze area TRIASSIC sequence RESPONSE
下载PDF
上一页 1 2 89 下一页 到第
使用帮助 返回顶部