地中电偶极源极低频电磁场的分布与传播特征

利用层状大地中偶极源响应的正演算法, 计算地中电偶极源激发的极低频地震电磁场并分析其在地球环境下的传播特征.设计了多个水平层状地球模型, 分别模拟和展示了深埋地中的电偶极源的响应和空间分布特征.重点分析了含地壳波导+LAI波导模型的高阻大地中, 倾斜电偶极源激励响应随观测点的偏移距和垂直位置、激励源深度、地壳波导结构和参数变化时各场量响应的幅频特征.研究表明, 用倾斜电偶极源模拟和分析高阻大地中孕震电磁辐射的响应及在大地电磁系统中的传播特性是可行的; 模拟的高阻大地中的电磁辐射在地壳波导和LAI波导中均表现有慢衰减或幅值增强特性, 但两个波导效应具有不同的频率选择性; 高阻大地中的电磁辐射在波导的高阻介质中具有幅值强、衰减慢的特点.建议在高阻地层出露的地表、井中或海底的高阻岩层中以及大气层中布设测站.

     

The periodic variations of the core drift rate: global and zonal motions (Mitteilung des Zentralinstituts für Physik der Erde,Nr. 1746)

Toroidal zonal motions at the top of the Earth's core were computed from the observed secular variation and investigated with regard to their time dependence. Previously derived results for a pure westward drifting core could be re-examined. Additionally, the well-known 66.7 years period was found to be an oscillation of the zonal velocity field of third degree. With respect to periodic constituents, the total magnetic core-mantle coupling torque according to the zonal motions is comparable with that derived for a pure westward drifting core. Some differences in period lengthes and amplitudes do not remove previously stated differences between the spectra of the magnetic and mechanical torques on principle.     

地幔对流与岩石层板块的相互耦合及影响──（Ⅱ）地幔混合对流理论及其应用

观测到的板块运动包含两种能量分布几乎相等的运动形态：极型场和环型场．纯粹的由热驱动的地幔自由对流不能预期和解释环型运动的产生．本文提出地幔混合对流理论,既考虑了热驱动的自由对流,也考虑了由板块自身激发的强迫对流．根据板块处于动力学平衡状态的观测事实,建立了相应的模型．数值结果表明,根据混合对流模型所预期的板块速度场,既能产生极型场,也能产生环型场,而且在空间分布特征及功率谱分布上与观测资料符合相当好．地幔物质的上升流动基本和洋脊对应,而下降流动和俯冲带对应．     

广西佛子冲铅锌矿田矿化蚀变特征及其成矿预测

广西佛子冲铅锌矿矿田位于桂东南博白-岑溪多金属成矿带的中段.矿区围岩蚀变强烈,类型繁多,其中以矽卡岩化、硅化和帘石化与成矿关系最为密切.矿体至围岩明显有矽卡岩化 - 强硅化 - 弱硅化 - 石英、碳酸盐化的蚀变分带特征.作者根据赋矿岩性、矿化蚀变分布、矿体产出特征及相关物探工作,提出六塘 - 龙树垌和牛卫 - 水滴两个找矿预测区.     

Palaeointensity In the Pelagic Realm: Marine Sediment Data Compared With Archaeomagnetic and Lake Sediment Records

Summary. Four box cores collected from the Ontong—Java plateau during the Eurydice expedition have been used to make relative geomagnetic palaeo-intensity measurements. Rock magnetic measurements on the sediments show that they are characterized by a uniform magnetic mineralogy, and that they are suitable for relative intensity estimates. These are obtained by normalizing the NRM by an ARM imparted in a low DC bias field. the palaeoceanographic event known as the preservation spike is used to establish a crude time-scale for the record so that it may be compared with other data from the same region, and also with global palaeointensity estimates. the marine sediment data are quite similar to Australian intensity data from lake sediments and archaeomagnetic sources, but as might be expected exhibit some obvious differences from the global record.     

地磁场能量在地球内部的分布及其长期变化

用国际参考地磁场模型(IGRF)分析了地磁场能量在地球内部的分布及其长期变化.结果表明,从1900年到2005年,地核以外地磁场总能量由6.818×1018J减少到6.594×1018J,减小了3.3%,地表以外地磁场总能量由8.658×101J减小到.63×101J,减小了11.4%.分析地球内部不同圈层地磁场能量的变化表明,地壳(A层)、上地幔(B层)、转换带(C层)、下地幔D′层的地磁场总能量在减小,但是下地幔"层的地磁场总能量却在快速增加.磁能密度随时间的变化更清楚地显示出磁能增加和减小的分界面在r=3840km处.上述结果表明,地核和地表以外地磁场总能量在趋势性减小的同时,也在进行重新分配.进一步分析表明,下地幔D"层磁能快速增长,主要是由高阶磁多极子的增强引起的.在地磁场倒转前,偶极矩减小而多极性相对增强在能量分布上的表现就是磁能向下地幔底部(特别是D"层)集中.     

BOOK REVIEWS

Books reviewed in this article: Aerial Photography and Remote Sensing Aerial photography and image interpretation for Resource Management . DAVID P. PAINE . Analytical Models and Techniques Spatial Processes Models and Applications A. D. CLIFF AND J. K. ORD Quantitative and Statistical Approaches to Geography: A Practical Manual JOHN A. MATTHEWS . Cartography and Maps Map Data Processing . HERBERT FREEMAN AND GOFFREDO G. PIERONI , eds. Computer-assisted Cartography: Principles and Prospects, 1982 . MARK S. MONMONIER . Cultural Navajo Architecture: Forms, History, Distributions . STEPHEN C. JETT AND VIRGINIA E . SPENCER . Rational Landscapes and Humanistic Geography . EDWARD RELPH . Economic The Structure and Control of a State Economy . W. L. L'ESPERANCE . Economic Geography . JAMES O. WHEELER AND PETER O. MULLER . The Myth of the Family Farm: Agribusiness Dominance of U.S. Agriculture . INGOLF VOCELER . Libya: The Experience of Oil . J. A. ALLEN . Geography of Public Finance, Welfare Under Fiscal Federalism and local Government Finance . ROBERT BENNETT . Environmental Management, Resources, and Systems Mountains and Man . LARRY W. PRICE . Environmental Geology . DONALD R. COATES . An Introduction to Environmental Systems . G. H. DURY . The Environment: Chinese and American Views . Edited by LAURENCE J. C. MA AND ALLEN G. NOBLE . Land Use in America . RICHARD H. JACKSON . Medical Conceptual and Methodological Issues in Medical Geography . MELINDA S. MEADE (ed.). Philosophy and Geographic Thought Birds in Egg/Eggs in Bird . GUNNAR OLSSON . PhysicaI Climatology: Selected Applications . J. E. OLIVER . Geomorphological Techniques . ANDREW GOUDIE (ed.). Political Politics, Geography and Behaviour . RICHARD MUIR AND RONAN PADDISON . The State of the World Atlas . MICHAEL KIDRON AND RONALD SECAL . Population The Population of the South . DUDLEY L. POSTON , JR . AND ROBERT H. WELLER , eds. Regional Latin America: Economic Development and Regional Differentiation . ARTHUR MORRIS . Developing the Amazon . EMILIO F. MORAN . Western Europe: A Systematic Human Geography . BRIAN W. ILBERY . Settlement Systems in Sparsely Settled Regions: The United States and Australia . RICHARD E. LONSDALEAND JOHN H. HOLMES , eds. African Perspectives: The Economic Geography of Nine African States . HARM DE BUJ AND ESMOND MARTIN , eds. Rural Nonmetropolitan America in Transition . AMOS H. HAWLEY AND SARA MILLS MAZIE , eds. Social Crime and Environment . R. NORMAN DAVIDSON . The Ghetto: Readings with Interpretations . JOE T. DARDEN , ed. Urban Urban Problems and Planning in the Developed World . MICHAEL PACIONE (ed.) Problems and Planning in Third World Cities . Edited by MICHAEL PACIONE . The City in West Europe . D. BURTENSHAW , M. BATEMAN , AND C. J. ASHWORTH .     

双侧向电阻率测井反演算法研究

双侧向测井仪因其激励源的复杂性给其测量数据的反演带来了极大的困难．本文利用变形玻恩（Born）迭代法对轴对称二维非均匀介质中双侧向测井仪的位场数据进行了严格反演．在每一次迭代过程中采用了高效数值模式匹配的正演计算方法,它可半解析地求出反演中所需计算的格林（Green）函数及其偏导数,同时利用所推导出的位场非线性积分方程中积分运算的半解析形式,大大提高了计算效率和反演质量．通过反演实例表明,反演结果与电导率原状剖面吻合较好,并且受噪声影响较小．     

不同带宽的防风固沙林流场结构及防风效能风洞实验

林带宽度是防风固沙林建植时要考虑的基本参数,研究不同带宽林带的防护效果对防风固沙林配置及构建具有重要的指导意义。通过风洞模拟实验,在7、10、15 m·s^-1风速条件下,对单行一带（Ⅰ型）、三行一带（Ⅱ型）、六行一带（Ⅲ型）和九行一带（Ⅳ型）共4种带宽的林带的迎风面、带中和背风面的风速进行了测定,分析了4种林带的风速流场、风速加速率和防风效果。结果表明：（1）4种林带流场结构和垂直风速变化规律相似,沿来风向均形成了林带上方和迎风面林缘附近的小范围高风速区及其后的风影区相互组合的流场结构;依据风速垂直变化规律划分为上部变化层（高度30~60 cm,受林带的影响最小）、中间变化层（高度5~20 cm,风速受林冠遮蔽作用,影响最大,且为风影区形成层）和近床面变化层（高度1~3 cm）。（2）4种林带在垂直纵剖面上的平均风速加速率随林带宽度的增大而减小,即Ⅰ型（0.90） > Ⅱ型（0.87） > Ⅲ型（0.79） > Ⅳ型（0.78）。（3）4种林带的防风效果为Ⅰ型和Ⅱ型林带相同,Ⅲ型和Ⅳ型林带相同,后2种林带的防风效果优于前2种林带,且4种林带的防风效能均随着风速的增大而减小。     

补偿向下延拓方法研究及应用

位场向下延拓是重、磁处理和解释的常用方法,但其不稳定性限制了其在资料处理及反演中的应用.本文基于补偿圆滑滤波思想以及空间域向下延拓迭代法,通过逐次补偿的办法实现位场的稳定向下延拓.同时,在频率域空间给出了该下延方法的频率域响应因子,并讨论了其低通滤波特性,理论模型和实际位场资料试验表明该方法向下延拓稳定性具有较高的延拓精度.将其应用于重力密度界面反演中,改进反演的稳定性,实际莫霍界面反演表明下延因子具备实用性.