北半球阻塞高压的维持Ⅱ:瞬变扰动强迫和平均流位涡平流的形成   总被引：4，自引：2，他引：4  

刘辉  曾庆存  吴国雄 《气象学报》1995,53(3):337-348

着重探讨大西洋阻高和东亚阻高个例中瞬变扰动位涡（涡度）输送强迫和太平洋阻高中平均流位涡平流的形成机理。结果表明，扰动在阻高西南部西风分流区因形变而产生的扰动拟能向更小尺度串级过程，并不是扰动位涡输送强迫形成的必要机理。扰－流相互作用在阻高西（北）部非分流气流中也十分显著。数值试验表明，这一相互作用也可能是扰动强迫作用形成的机理。而青藏高原和附近海陆对比的强迫作用则可能是太平洋阻高中平均流的位涡平流形成的重要因素。对比分析表明，阻高维持机制的地域性差别可能与其上游（如青藏高原地区、落基山脉）地形和热源强迫作用不同有关。  相似文献   

山东沂沭裂谷系含金斑岩铜矿床成矿地质特征     

杨志达 《华东地质学院学报》1987,(4)

沂沐裂谷是中国东部呈扇形展布的大陆裂谷系,从晚侏罗至白垩世裂谷岩浆活动强烈,发育了一套碱性、钙碱性火山建造,尤以中生代钙碱性火山活动具有特色,并常常形成许多巨大的古火山机体,本文通过对产于古火山机体中两个含金斑岩铜岩床研究,初步得出其主要成矿地质特征。  相似文献   

我国首次发现的碳氢钠石     

杨清堂 《岩石矿物学杂志》1987,6(1):87-91

碳氢钠石是一种无水碱金属碳酸盐矿物,最初发现于美国的绿河盆地。一九八二年,在我国河南省泌阳凹陷首次发现。该矿物的化学成分是Na_2CO_3和NaHCO_3,分子式是:Na_2CO_3·3NaHCO_3。该矿物晶体呈板状,无色透明,主要产在重碳钠盐组成的碱矿层中。经测试确定,该矿物属二轴晶负光性,主折射率:Ng=1.531,Nm=1.524,Np=1.435,2V=31.45°;晶胞参数:a=10.046,b=15.633,c=3.492,a=92°8′,β=95。42′,γ=108°34′;最强的粉晶衍射线有:3.70(35),2.97(100),2.67(41),2.213(60);主要的红外光谱吸收带是:2616,1692,1662,1359,1048,1018,839,677cm_(-1)。据碳氢钠石的产状和共生组合特征,该矿物产于富钠,高P_(CO_2)的碳酸盐型内陆盐湖,是较高温度条件下快速蒸发的产物。  相似文献   

大陆动力学演化与成矿研究: 历史与现状   总被引：21，自引：8，他引：21  

毛景文  谢桂青  李晓峰  张作衡  王义天  王志良  赵财胜  杨富全  李厚民 《矿床地质》2005,24(3):193-205

地球动力学演化过程与成矿作用是当今矿床学研究的前沿。文章回顾了自20世纪60年代以来，有关大陆动力学演化与成矿的研究历史和当前的研究动向。综述了几个研究大阶段，即：海底喷流成矿作用、大陆边缘成矿作用、板内成矿作用及地质历史演化过程的大陆汇聚或增生与多期次成矿。同时，以华南地区为例，将大陆侧向和垂向增生作为切入点，阐述了华南世界级有色、稀有、贵金属成矿省在地质历史过程中的成矿作用，并提出在该成矿省进一步实现找矿突破的重要科学问题。  相似文献   

A crustal seismic velocity model for the UK, Ireland and surrounding seas   总被引：1，自引：0，他引：1  

Annabel Kelly  Richard W. England  Peter K. H. Maguire 《Geophysical Journal International》2007,171(3):1172-1184

A regional model of the 3-D variation in seismic P -wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity–depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 × 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data.  相似文献   

Seismic anisotropy of the Slave craton, NW Canada, from joint interpretation of SKS and Rayleigh waves   总被引：2，自引：0，他引：2  

David Snyder  Marianne Bruneton 《Geophysical Journal International》2007,169(1):170-188

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Determining magma flow in sills,dykes and laccoliths and their implications for sill emplacement mechanisms     

Ken Thomson 《Bulletin of Volcanology》2007,70(2):183-201

Three-dimensional seismic data from the Faeroe-Shetland Basin provides detailed information on the relationships between sills, dykes, laccoliths and contemporaneous volcanic activity. The data shows that sills are predominantly concave upwards, being complete or partial versions of radially or bilaterally symmetrical forms that possess flat inner saucers connected to a flat outer rim by a steeply inclined sheet. Such morphologies are only partially modified by pre-existing faults. Sills can be sourced from dykes or the steep climbing portions of deeper sills. Both sills and dykes can provide magma to overlying volcanic fissures and sills can be shown to feed shallow laccoliths. Magma flow patterns, as revealed by opacity rendering, suggest that sills propagate upwards and outwards away from the magma feeder. As an individual sill can consist of several leaves emplaced at different stratigraphic levels, and as a sill or dyke can provide magma to volcanic fissures, other sills and laccoliths, the data suggests that neutral buoyancy concepts may not provide a complete explanation for the mechanism and level of sill emplacement. Instead, the data suggests that the presence of lithological contrasts, particularly ductile horizons such as overpressured shales may permit sill formation at any level below the neutrally buoyant level. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Ken Thomson–deceased, April 2007  相似文献   

Numerical experiments on the generation of long ocean waves in coastal waters of the Buenos Aires province,Argentina     

Walter C. Dragani 《Continental Shelf Research》2007

A numerical model (two horizontal dimensions, vertically integrated) is used to investigate the generation of long ocean waves, ranging from 20 min to almost 2 h, at Buenos Aires continental shelf. The domain includes the Río de la Plata estuary and the continental shelf together and extends from 33.5° to 40.5°S latitude, and from 51° to 63°W longitude. Sea-level oscillations are modeled by forcing with passage of atmospheric cold fronts and atmospheric gravity waves. Both forcing mechanisms, which have been present during high activity lapses of long ocean waves, are mathematically implemented. After several numerical simulations, it is concluded that the pressure and wind fields associated to cold fronts do not generate long ocean waves in the area, though they do produce disturbances with periods longer than the tidal ones. On the other hand, it is so concluded that atmospheric gravity waves are an effective mechanism to force long ocean waves. Results obtained show that generation of long ocean waves is highly sensitive depending on the propagation direction and the phase speed of the atmospheric gravity waves. The long ocean wave event detected during the large-amplitude gravity-wave event of 13 October 1985 is successfully simulated. Finally, all our results suggest that atmospheric gravity waves are a highly effective mechanism forcing for the generation of long ocean waves in Buenos Aires coastal waters.  相似文献   

Unstructured,anisotropic mesh generation for the Northwestern European continental shelf,the continental slope and the neighbouring ocean     

Sébastien Legrand  Eric Deleersnijder  Eric Delhez  Vincent Legat 《Continental Shelf Research》2007

A new mesh refinement strategy for generating high quality unstructured meshes of the Northwestern European continental shelf, the continental slope and the neighbouring ocean is presented. Our objective is to demonstrate the ability of anisotropic unstructured meshes to adequately address the challenge of simulating the hydrodynamics occurring in these three regions within a unique mesh. The refinement criteria blend several hydrodynamic considerations as the tidal wave propagation on the continental shelf and the hydrostatic consistency condition in steep areas. Several meshes illustrate both the validity and the efficiency of the refinement strategy. The selection of the refinement parameters is discussed. Finally, an attempt is made to take into account tidal ellipses, providing another cause for anisotropy in the mesh.  相似文献   

Simulation analysis on the regulation of overflow ecological water consumption in arid areas——A case study in the Canmrik ecological area of the mainstream zone of the Tarim River     

CHEN Xi  HUANG Yue  QIAN Jing  LIU HaiLong  FENG XianWei  LIU Ying  BAO AnMing  WANG WeiSheng 《中国科学D辑(英文版)》2007,50(Z1)

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