青海省气候异常偏暖的成因分析   总被引：3，自引：1，他引：2  

时兴合  赵燕宁  秦宁生 《中国沙漠》1999

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4-Dimensional Models of Deformation of the Earth's Crust and Earthquake Prediction     

A.V.Ovcharenko 《中国地震研究》1999,(1)

Traditionally, when creating 4-D models of elastic offsets in the Earth's crust, the data from geodesic and GPS monitoring of offsets on the ground surface, earthquake catalogs, monitoring of the water level and radon content in wells, sea level fluctuations, as well as gravitational and magnetic fields, etc., can be taken as bases for information. In essence, the reason for creating a 4-D model of slow elastic deformations is to approximate the process by a set of plane deformation solitons (solitary waves). The parameters of a set of deformation solitons are obtained by a two-stage inversion. First, the parameters of the model are determined in a kinematic way by the use of a modified simplification of the method. Then, a calibration of the amplitude characteristics of the model is carried out in terms of elastic dynamic offsets. Taking Ural, Northern Tianshan, Greece, and China as examples, models for these regions are created on the basis of seismological, geodesic, deformation, hydrogeological, and  相似文献   

Breaking Criteria for Regular Waves on Gentle Slopes     

李玉成  崔丽芳  于洋  滕斌 《中国海洋工程》1999,(4)

Nelson pointed out that the wave breaking criterion(H/d)_b for gentle slopes(i<1/100),inwhich H is the wave height and d is the water depth at the breaking point,is smaller than that for beachslopes of i>1/100),i.e.,the value of(H/d)_b for gentle slopes may be smaller than 0.6.Goda indicatedthat the wave breaking criterion given by himself is a result based on theoretical study,so it should be alsocorrect and can be used for gentle beaches,i.e.,the value of(H/d)_b for gentle slopes may be still largerthan 0.7.By use of high order nonlinear wave theory,this problem is analyzed in this study and the reasonwhy there is a large difference between different studies is explained.Moreover,the bottom energy loss dur-ing wave propagation is considered and the critical slope for the absence of wave breaking is also analyzed.  相似文献   

Normalization of Hydrodynamic Coefficients in Morison Equation     

LI Yucheng Professor  the State Key Laboratory of Coastal  Offshore Engineering  Dalian University of Technology  Dalian  P. R. China. 《中国海洋工程》1999,(2)

-The hydrodynamic coefficients C_d and C_m are not only dependent on the size of slender cylin-der,its location in water,KC number and Re number,but also vary with environmental conditions,i.e.,in regular waves or in irregular waves,in pure waves or in wave-current coexisting field.In this paper,thenormalization of hydrodynamic coefficients for various environmental conditions is discussed.When aproper definition of KC number and proper characteristic values of irregular waves are used,a unified re-lationship between C_d,C_m and KC number for regular waves,irregular waves,pure waves and wave-cur-rent coexisting field can be obtained.  相似文献   

Basin effects on ground motion: the case of a high-resolution experiment in Cephalonia (Greece)     

N. Theodoulidis  G. Cultrera  C. Cornou  P.-Y. Bard  T. Boxberger  G. DiGiulio  A. Imtiaz  D. Kementzetzidou  K. Makra  The Argostoli NERA Team 《Bulletin of Earthquake Engineering》2018,16(2):529-560

In this study data and results of a high-resolution experiment in Cephalonia (Greece) regarding empirical basin effects are presented. A total of 59 velocimeters and 17 accelerometers were deployed in the basin of Argostoli Cephalonia (Greece), for a period of 7 months (September 2011–April 2012). Due to high seismicity of the western Greece and surrounding area this array recorded thousands of local, regional and global events. Data used in this work come from a selection of 162 regional and local earthquakes, 3 km ≤ R ≤ 600 km, with magnitude range, 1.0 ≤ M ≤ 5.2. Based on high signal-to-noise ratio recordings and two selected reference stations, variation of several intensity measures (PGA, PGV, Arias Intensity, Cumulative Absolute Velocity), significant duration, HVSR and SSR of ground motion recordings on soil sites within the basin is carefully examined for a range of frequencies of engineering interest. Comparison of results with a detailed 2D geologic model shows a good consistency both in amplification and frequency domain. Influence of “reference” site on ground motion variation of soil sites is also discussed in light of our results. Finally, it is suggested that 2D or/and 3D theoretical modeling should be performed given the availability of geological and geophysical parameters to define a realistic model of the basin. Results of this study can undoubtedly serve in model validation and improvement of ground motion simulation tools.  相似文献   

Deglaciation history at the Alpine-Mediterranean transition (Argentera-Mercantour,SW Alps) from 10Be dating of moraines and glacially polished bedrock     

Yann Rolland  Romain Darnault  Régis Braucher  Didier Bourlès  Carole Petit  Stéphane Bouissou  ASTER Team 《地球表面变化过程与地形》2020,45(2):393-410

Estimating the extent and age of the last glacial maxima as well as the chronology of glacial recessions in various environmental contexts is key to source-to-sink studies and paleoclimate reconstructions. The Argentera-Mercantour massif is located at the transition between the Alps and the Mediterranean Sea, therefore, its deglaciation chronology can be compared to the sediment budget of the Var River basin. Based on 13 new cosmic-ray exposure (CRE) beryllium-10 (¹⁰Be) datings performed on moraines and polished crystalline bedrocks and 22 reassessed ¹⁰Be CRE ages from similar altitude nearby steep basement surfaces, and from a lake sediment core, we can constrain the deglaciation chronology of the Argentera-Mercantour massif. These data allow for the first time to fully reconstruct the deglaciation history at the scale of the entire massif in agreement with a major glacier recession at c. 15 ka, at the onset of Bølling transition between the Oldest and Older Dryas. Main deglaciation of the upper slopes [2700–2800 m above sea level (a.s.l.)] occurred after the Last Glacial Maximum (LGM) at 20.8–18.6 ka, followed by the main deglaciation of the lower slopes (2300 m a.s.l.) at 15.3–14.2 ka. Finally, the flat polished surfaces above 2600 m a.s.l. and the zones confined within narrow lateral valleys were likely affected by progressive ice melting of remaining debris covered glaciers and moraine erosion following the Younger Dryas re-advance stage between 12 and 8–9 ka. At lower elevations, the Vens Lake located at 2300 m a.s.l., allows evidence of the onset of lake sedimentation at c. 14 ka and a transition towards a vegetated environment that mainly occurred before 8 ka. Moraine final stabilization at 5 ka might reflect denudation acceleration during the Holocene humid phase. This contribution reveals a glacier–climate relationship more sensitive to warming phases in the southern Alps highlighted by a major decrease of glaciers after c. 15 ka. This major deglaciation is correlated with a 2.5-fold decrease of sediment discharge of rivers into the Mediterranean Sea. © 2019 John Wiley & Sons, Ltd.  相似文献   

Late Paleozoic Fluid Systems and Their Ore-forming Effects in the Yuebei Basin, Northern Guangdong, China   总被引：1，自引：0，他引：1  

DENG Jun  YANG Liqiang  SUN Zhongshi  WANG Jianping  WANG Qingfei  CHENG Xueming  ZHOU Yinghua State Key Laboratory of Geological Processes  Mineral Resources  China University of Geosciences  Beijing  Key Laboratory of Lithosphere Tectonics  Lithoprobing Technology of the Ministry of Education  China University of Geosciences  Beijing School of Earth Sciences  Jilin University  Chuangchun  Jilin 《《地质学报》英文版》2005,79(5):673-687

Based on detailed and systematic researches of the geology of ore deposits, fluid inclusions and isotope geochemistry etc., and regarding the Late Paleozoic fluid system of the Yuebei Basin as an integrated object in this paper, we have revealed the temporo-spatial evolution law of the basin＇s fluid system and discussed its ore-forming effects by simulating and analyzing the distribution of ore-forming elements, the fluid thermodynamics and dynamics of evolution processes of this basin. The results show that Late Paleozoic ore-forming fluid systems of the Yuebei Basin include four basic types as follows. （1） The sea floor volcanic-exhalation system developed during the rapid basin slip-extension stage in the Mid-Late Devonian, which affected the Dabaoshan region. It thus formed the Dabaoshan-type Cu-Pb-Zn-Fe sea floor volcanic-exhalation sedimentary deposits. （2） The compaction fluid system developed during the stable spreading and thermal subsidence-compression stage of the basin in the Mid-Late Devonian. The range of its effects extended all over the whole basin. It resulted in filling-metasomatic deposits, such as the Hongyan-type pyrite deposits and pyrite sheet within the Fankou-type Cu-Pb-Zn-S deposits. （3） The hot water circulation system of sea floor developed during the stage of basin uplifting and micro-aulacogen from the late Late Carboniferous to Middle Carboniferous. The range of its effects covered the Fankou region. It thus formed MVT deposits, such as the main orebody of the Fankou-type Pb-Zn-S deposits. （4） The gravity fluid system developed during the stage of fold uplifting and the basin closed from Middle Triassic to Jurassic, forming groundwater hydrothermal deposits, e.g. the veinlet Pb-Zn-calcite orebodies of the Fankou-type Pb-Zn- S deposits. Migration and concentration of the ore-forming fluids were constrained by the state of temporo-spatial distribution of its fluid potential. Growth faults not only converged the fluids and drove them to move upwards, but also the fluids often crossed the faults to the edges of the basin at the bottom of these faults and the lithologic interfaces, and even migrated to the basin＇s edges from top to bottom along the faults, which may be one of the basic reasons for the stratabound deposits to cluster mainly along the contemporaneous faults on the inner border of the basin. The superposed mineralization resulting from the multi-stage activity of contemporaneous faults and ore-forming fluid systems in the basin may be one of the key factors for forming superlarge ore deposits.  相似文献   

Comparison of the Typical Metallogenic Systems in the North Slope of the Tongbai-East Qinling Mountains and its Geologic Implications     

ZHANG Jing  CHEN Yanjing  QI Jinping  GE Jun State Key Laboratory of Geological Process  Mineral Resources  China University of Geosciences  Beijing  China Key Laboratory of Metallogenic Dynamics  Guangzhou Institute of Geochemistry  the Chinese Academy of Sciences  Guangzhou  China 《《地质学报》英文版》2009,83(2)

The Tongbai-East Qinling Mountains,an important part of the Central orogenic belt,is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type (Volcanogenic Massive Sulfide type)metallogenic systems.The Dahe and Shuidongling VMS-type Cu-Zn deposits,located in the Erlangping Group in Tongbai and East Qinling Mountains,respectively, show similar geological and geochemical features.The Huoshenmiao Formation in the East Qinling region and the Liushanyan Formation i...  相似文献   

Revision of the Clam Shrimp Genus Magumbonia from the Upper Jurassic of the Luanping Basin,Hebei,Northern China     

Peter BENGTSON  Helmut WILLEMS  Hiramichi HIRANO 《《地质学报》英文版》2009,83(1)

The diverse clam shrimp Nestoria-Keratestheria fauna is widely distributed in the Dabeigou Formation in northern Hebei and eastern Inner Mongolia of China.Its important component genus Magumbonia from the Dabeigou Formation in the Luanping Basin,northern Hebei,China,is revised on the basis of a scanning electron microscope (SEM) examination of the type species M.jingshangensis Wang,1984,which revealed morphological features not recognized previously.These include coarse reticulation on the umbo and promi...  相似文献   

龙卷风的漏斗结构理论   总被引：4，自引：1，他引：3       下载免费PDF全文

刘式适  付遵涛  刘式达  许焕斌  辛国君  梁福明 《地球物理学报》2004,47(6):959-963

龙卷风是大气中风速和垂直速度极大的小尺度系统.本文用气压梯度力、惯性离心力、黏性力三力平衡的柱坐标(r,θ,z)下的大气动力和热力学方程组,求龙卷风的三维速度场(vr,vθ,vz),从理论上绘制出龙卷风的三维漏斗型结构.充分说明龙卷风由涡旋流和急流这两种流叠加而成,涡旋流是由惯性离心力造成的,急流是由水平辐合辐散而引起的强对流.龙卷风是在极端不稳定的大气层结中形成的.  相似文献