关于华南大地构造问题的再认识   总被引：29，自引：3，他引：29  

赵崇贺 《现代地质》1996,10(4):512-517

自８０年代以来，华南大地构造格局问题的讨论是我国地学的热点之一。有关华南陆块地质构造演化及形成时代存在多家之说，其中“江南古陆”是否存在与原“板溪群”时代的归属是争论的焦点。许多学者从不同的角度提出了各种观点和构造演化模式。从近几年来在皖南、赣东北地区的一系列新发现，可以得出如下看法：（１）“板溪群”不是一个前震旦纪的变质地层单位；（２）“江南古陆”是不存在的；（３）华南不存在加里东后地台，而存在晚古生代洋盆，它可能是东特提斯洋的一部分；（４）印支运动在赣东北地区有重要的表现，晚古生代浅变质岩和蛇绿混杂岩是它的岩石记录  相似文献   

On barotropic and baroclinic tides over an arbitrary sloping topography     

J. Y. Le Tareau  R. Maze 《Annales Geophysicae》1996,14(9):961-975

Some theoretical concepts about the frictionless dynamics of propagation of the barotropic tide over two-dimensional continental slopes of arbitrary shape are developed. A numerical procedure which generalizes the exact solution obtained over a rectilinear sloping topography is given. This technique can be applied to compute the harmonic components of the barotropic tide everywhere over sloping bottom contours of any shape. It permits in particular the avoidance of discontinuities at the boundaries of rectilinear-continental-slope profiles. The barotropic tidal results are used afterwards to calculate the barotropic forcing for the generation of internal tides. Numerical experiments are performed to study the interaction between the tide and some typical sloping topographies. A three-layered model is used for this purpose. Results are compared with those previously obtained over a rectilinear continental slope.  相似文献   

Radionuclides and sulfur content in Mount Etna plume in 1983–1995: new constraints on the magma feeding system     

M. F. Le Cloarec  M. Pennisi 《Journal of Volcanology and Geothermal Research》2001,108(1-4)

Radionuclide activities (²¹⁰Pb, ²¹⁰Bi, ²¹⁰Po) were investigated in Mount Etna plume from 1983 to 1995. At SE crater the long-term observation (12 years) of the ²¹⁰Po/²¹⁰Pb ratio shows that it can behave as a degassing vent not directly related to the main magma reservoir depending on the magma level inside the volcano. Since 1992, the simultaneous determination of radionuclides and sulfur in the main plume results in new constraints on the degassing model of Lambert et al. (Earth Planet. Sci. Lett., 76 (1986) 185). The ²¹⁰Po/SO₂ and ²¹⁰Pb/SO₂ ratios enable us to identify two sources of ²¹⁰Po in the plume: one is magmatic, correlated with SO₂, the other one is an additional component issued from the decay of ²¹⁰Pb in the shallow degassing cell, and depends directly on the residence time of the gases before their emission. Estimations of the volume of degassing magma, the residence time of the gases and the proportion of undegassed magma renewing the shallow degassing cell are given for the period 1992–1995. During the 1992 eruption, the rate of degassing magma volume is estimated to have been as high as 5×10⁶ m³/day, and the volume of the shallow degassing magma reservoir about 0.5 km³. In 1994 and 1995 the rate of non-erupted degassing magma volume was estimated to have been about 0.18 km³/year. During the entire 1983–1995 period, only 15–20% of the degassed magma was erupted.  相似文献   

A Model of PCB Bioaccumulation in the Sea Bass Food Web from the Seine Estuary (Eastern English Channel)     

V. Loizeau  A. Abarnou  P. Cugier  A. Jaouen-Madoulet  A. -M. Le Guellec  A. Menesguen 《Marine pollution bulletin》2001,43(7-12):242-255

A bioaccumulation model was developed to simulate the PCB contamination in the sea bass food web from the Seine Estuary. The model relies upon a contaminant mass balance budget for each biological species. Biological processes determine the extent of bioaccumulation: respiration and feeding rates control the uptake of contaminants whereas excretion, spawning, and growth act on the chemicals removal. A step-by-step modelling approach was followed. A first version was a steady-state model validated for the bioaccumulation processes. In the second version seasonal variation was taken into account, and finally in the third version, the model was coupled with a population dynamics model to describe PCB contamination in each age class.  相似文献   

从陕西旬邑上新生界剖面看黄土高原新近系/第四系界线   总被引：6，自引：2，他引：6  

薛祥煦  岳乐平  王建其 《地层学杂志》2001,25(3):161-165

新近系 /第四系界线在黄土高原大都以磁性 M/ Ga界线为界进行划分 ,它与岩性分界往往并不一致 ,后者都低或高于前者一小段距离。根据旬邑剖面的岩性、孢粉、古动物、磁化率、粒度及地化资料 ,并参考了其他一些剖面的岩性 ,认为以二者之间的过渡层底为界进行划分比较合理  相似文献   

Infrasonic Signal Detection and Source Location at the Prototype International Data Centre   总被引：1，自引：0，他引：1  

D. J. Brown  C. N. Katz  R. Le Bras  M. P. Flanagan  J. Wang  A. K. Gault 《Pure and Applied Geophysics》2002,159(5):1081-1125

—?This paper describes an automatic and interactive data processing system designed to locate impulsive atmospheric sources with a yield of at least one kiloton by detecting and characterizing the airborne infrasound radiated by the source. The infrasonic processing subsystem forms part of a larger system currently under development at the Prototype International Data Center (PIDC) in Arlington, Virginia where seismic, hydroacoustic, radionuclide and infrasonic methods are used to detect and locate impulsive sources in any terrestrial environment. Infrasonic signal detection is achieved via a coincidence detector which requires both the normalized cross correlation and the short-term-average/long-term-average ratio of a beam in the direction of maximum correlation to exceed predetermined threshold values simultaneously before a detection is declared. The infrasound propagation model currently used to infer travel-time information assumes the horizontal sound speed across the ground to be 320.0?m/s. This crude model is currently being replaced by a model which predicts travel-time information through a ray-tracing algorithm for acoustic waves in an atmosphere with seasonal representations for temperature and wind. A novel feature of the source location process is the fusion of all available arrival information, whether it be seismic, hydroacoustic or infrasonic to locate a single source where it is reasonable to hypothesize a common source. In its final configuration the infrasonic subsystem will routinely process data from the global 60-station International Monitoring System (IMS) infrasonic network currently under development.  相似文献   

GIS支持的土壤贫瘠化区域分异研究——以福建为例   总被引：1，自引：8，他引：1  

钱乐祥  许叔明  秦奋  李斌  朱鹤健 《地理科学》2002,22(1):85-90

区域分异研究是区域开发及生态环境保护的重要基础工作 ,GIS在土壤贫瘠化区域分异研究中的应用是GIS技术在土壤地理学中应用的重要方面。以福建为例 ,在GIS技术支撑下 ,利用多元数理统计方法 ,提出了一个反映土壤养分贫瘠化状况的综合性指标 ,计算并输出福建土壤贫瘠化等级图 ,据此分析了土壤贫瘠化的区域分异特征 ,表明 ,GIS技术在这一领域的应用具有先进性、区域分异研究工作的高效性和成果的实用可靠性。  相似文献   

Sensitivity of an atmospheric general circulation model to prescribed SST changes: feedback effects associated with the simulation of cloud optical properties   总被引：1，自引：0，他引：1  

Hervé Le Trent  Zhao-Xin Li 《Climate Dynamics》1991,5(3):175-187

This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute for Meteorology. Guest Editor for these papers is Dr. L. Dumenil  相似文献   

Ilot de Chaleur a Quebec: Cas d'hiver     

Richard Leduc  Ghislain Jacques  Michel Ferland  Claude Le Lièvre 《Boundary-Layer Meteorology》1981,21(3):315-324

  相似文献   

Tritium-Verteilung,Durchmischungsverhältnisse und Altersstruktur der Wassermasse im Vierwaldstättersee     

Frau Dr. M. M. Bezzegh  Prof. Dr. H. L. Le Roy  K. Steiner 《Aquatic Sciences - Research Across Boundaries》1977,39(2):201-225

Tritium of thermonuclear origin was measured in four different depth profiles in the Lake of Lucerne. Its concentration distribution yielded information on the mixing within the water mass under observation. A simple model was established for approximating the age structure of the water layers.  相似文献