关于倾斜脉的重力异常公式及理论曲线正误的商榷     

袁业培  金文丽 《华东地质学院学报》1986,(2)

本文着重讨论了重力勘探教材中关于倾斜脉的△g、V_(xz)、V_(zz)理论公式及二次微商理论曲线的正误问题。文中给出了无限延深倾斜脉的准确的 V_(xz)及 V_(zz)理论曲线,并且指出应该充分地利用 V_(xz)V_(zz)异常特征解释推断脉的倾向.  相似文献   

莺－琼盆地YA13－1气田热流体活动与有机／无机成岩响应   总被引：7，自引：0，他引：7       下载免费PDF全文

孙永传  陈红汉  李蕙生  陆永潮  张启明  张国华  朱河清 《地球科学》1995,(3)

根据钻井中途测试（ＤＳＴ）、重复地层测试（ＲＦＴ）、镜质体反射率（Ｒ０）、流体包裹体分析和粘土矿物Ｘ射线衍射全定量分析等综合研究发现，莺－琼盆地ＹＡ１３－１气田存在４期热流体活动；南侧的崖南地区和西侧的莺歌海盆地是其两个重要的热流体物质源和动力源；多期热流体活动在ＹＡ１３－１地区不仅造成热异常和物质迁移，而且还引起了不同的有机／无机成岩响应，如骨架颗粒的多期溶蚀作用、至少两期的次生加大作用、粘土矿物转化和有机质热成熟作用异常。第二、第三期热流体因出溶作用形成ＹＡ１３－１气田大规模的天然气聚集。  相似文献   

地幔对流与岩石层板块的相互耦合及影响──（Ⅰ）球腔中的自由热对流     

叶正仁  滕春凯 《地球物理学报》1995,38(2):174-181

板块运动是地幔对流的主要证据之一．同时，作为地球动力系统中一个相对独立部分，板块自身的存在和运动对地幔内部物质的流动形态有巨大影响．地幔内部的流动由两部分组成：一是由内部非绝热温度差异造成的自由对流解；另一部分是由在地表运动的板块所激发．作为系列工作的第一部分，本文研究球腔中的自由热对流问题．得到了对地幔对流研究有实际意义的下边界为自由、上边界为刚性情况下的临界瑞利数值，不同的瑞利数时球腔内流场和温度场的分布形态等．  相似文献   

A preliminary study of the effects of some flow parameters in the generation of poloidal and toroidal energies within a 3-D spherical thermal-convective system with variable viscosity     

Albert T. Hsui  Woo-Sun Yang  John R. Baumgardner 《Pure and Applied Geophysics》1995,145(3-4):487-503

The effects of variable viscosity on flow dynamics within spherical shells are investigated using a finite-element thermal convection model, and preliminary result for cases with relatively low Rayleigh numbers and small viscosity contrasts are reported. These results demonstrate some general effects of viscosity variation on mantle dynamics, and, in particular, the generation of toroidal energy. Since lateral viscosity variations are necessary in the generation of toroidal motion in a thermally driven convective system, it is not surprising our results show that flows with greater viscosity contrasts produce greater amounts of toroidal energy. Our preliminary study further shows that solutions become more time-dependent as viscosity contrasts increase. Increasing the Rayleigh number is also found to increase the magnitude of toroidal energy. Internal heating, on the other hand, appears to lead to less toroidal energy compared wth bottom heating because it tends to produce a thermally more uniform interior and thus smaller viscosity variations.  相似文献   

论浙江火山岩区金银矿床的成矿物质来源   总被引：2，自引：0，他引：2  

徐国风 《地球科学》1987,(4)

稳定同位素和地质特征的研究,结果表明浙江火山岩区金银矿床的成矿物质系多元来源。金属和挥发性组分来源于岩石圈深部(下地壳或上地幔)和上地壳,成矿流体是大量大气水和少量岩浆水的混合溶液.金银矿化与板块运动及地热流体对流体系有关.  相似文献   

Small channels: Their experimental formation,nature, and significance     

A. J. Moss  Patricia Green  J. Hutka 《地球表面变化过程与地形》1982,7(5):401-415

The manner in which small channels are generated, from plane beds beneath sheet flows, has been experimentally elucidated. On plane, erodible, sand beds, the transition from thin, supercritical sheet flows to the channelled condition was studied over ranges of discharge, slope, and temperature. Secondary flow of the second kind, its action facilitated by steep vertical velocity gradients in the primary flows, caused sheet-flow instability. Along junctions between neighbouring secondary cells, both either raised or lowered elements of the primary flow. In the latter case, fast surface water was lowered to the bed, causing relatively intense, local, longitudinal scour. Dislodged grains were moved divergently to either side, leaving straight, central trenches. Development of positive feedback between cells and trenches led to rapid enlargement of the latter and concomitant growth of paired levees. The resulting structures, ‘protochannels’, were themselves ephemeral, developing two types of instability associated with secondary flow of the first kind. Firstly, small deviations from bilateral symmetry were enhanced, causing evolution into meandering channels. Secondly, headcutting led to multiple tributary development and, at resulting confluences, the action of strong pairs of secondary cells led to the development of braiding channels. Because they are shortlived, protochannels are but rarely seen in nature. Their seeding is markedly temperature-sensitive, reflecting their frictional origin. The erosive power of shallow overland flow largely depends on flow-energy concentration by secondary flow, firstly into channels, then within the channels themselves. Suppression of secondary flow, as by intense raindrop bombardment, can stabilize sheet flows. In deeper water, the effects of secondary flow appear relatively less dramatic. However, even if such motion is weak, bedload divergence from attachment lines can favour entrainment locally and thus affect bed geometry. Analogy between our results and river behaviour appears close and. on continental shelves where water must often flow as sheets, structures resembling giant protochannels evidently persist.  相似文献   

A Note on the Mixing Length Theory and Massive Star Evolution     

Li－CaiDeng  Da－RunXiong 《中国天文和天体物理学报》2001,1(1):50-56

1 INTRODUCTIONThe mixing length theory (MLT) for stellar convection originally developed by Vitense(1953, 1958) has been the most popularly used local convection theory in the studies of stellarstructure and evolution. The theory was later modified and revised by many investigators,who suggested some different expressions. In fact, MLT is not a real hydrodynamic theory,rather, it is a simple "ballistic" theory which traces the motion of imaginary convective elements. In reality j stell…  相似文献   

On determining the noon polar cap boundary from SuperDARN HF radar backscatter characteristics     

M. Pinnock  A. S. Rodger 《Annales Geophysicae》2001,18(12):1523-1530

Previous work has shown that ionospheric HF radar backscatter in the noon sector can be used to locate the footprint of the magnetospheric cusp particle precipitation. This has enabled the radar data to be used as a proxy for the location of the polar cap boundary, and hence measure the flow of plasma across it to derive the reconnection electric field in the ionosphere. This work used only single radar data sets with a field of view limited to 2 h of local time. In this case study using four of the SuperDARN radars, we examine the boundary determined over 6 h of magnetic local time around the noon sector and its relationship to the convection pattern. The variation with longitude of the latitude of the radar scatter with cusp characteristics shows a bay-like feature. It is shown that this feature is shaped by the variation with longitude of the poleward flow component of the ionospheric plasma and may be understood in terms of cusp ion time-of-flight effects. Using this interpretation, we derive the time-of-flight of the cusp ions and find that it is consistent with approximately 1 keV ions injected from a subsolar reconnection site. A method for deriving a more accurate estimate of the location of the open-closed field line boundary from HF radar data is described.  相似文献   

永平水泄铜钴矿控矿因素     

杨宏城 《云南地质》2007,26(4):416-420

水泄铜钴矿区地质条件较为复杂,控矿因素较多,通过分析认为主要受断层及岩性控制,地层初始富集,构造及区域变质作用提供通道及热源。水的循环、溶解作用形成热卤水成矿。  相似文献   

Stress induced time dependent behavior of clayey soils     

Sudhir Kumar Tewatia  Pratima Rani Bose  Asuri Sridharan  Sunanda Rath 《Geotechnical and Geological Engineering》2007,25(2):239-255

It is shown that time compression curve obtained from one-dimensional consolidation curve in the laboratory may include six phases. These are initial compression, first primary compression, transition from first primary compression to second primary compression, second primary compression, and transition from second primary compression to creep and lastly creep. This paper attempts to identify the quantitative beginnings and characteristics of these phases. A mathematical characteristic of all the soils that follow primary consolidation as per Terzaghi’s one dimensional consolidation theory is derived. It is known as the constant of primary consolidation. It is used to study the beginning of secondary consolidation and its effects on primary consolidation. Another characteristic of soils for creep and total absence of primary compression is derived. Methods are suggested for the determination of coefficients of Primary and Secondary consolidations and the compression index.  相似文献