Periodicity of magnetic intensities in magnetic anomaly profiles: the Cenozoic of the South Atlantic     

B. D'Argenio  M. Iorio  D. H. Tarling 《Geophysical Journal International》1996,127(1):141-155

Spectral analyses of several published magnetic anomaly profiles from Candé & Kent (1992a) were undertaken prior to analysing, in the same way, raw magnetic anomaly data from similar parts of the South Atlantic. It was found that similar and distinct medium and short wavelengths were present in both the published and raw data. When these are converted into the time domain using the average rate of spreading for each profile, these periodicities appear similar, possibly identical, to those expected from the long-term eccentricity orbital parameters (Fischer, DeBoer & Premoli Silva 1990). While such correlations are not necessarily causative, they suggest that magnetohydro-dynamical processes near the core-mantle boundary may be affected by gravitational changes due to planetary orbital perturbations.  相似文献   

Three-dimensional Rayleigh hysteresis of oriented core samples from the German Continental Deep Drilling Program: susceptibility tensor, Rayleigh tensor, three-dimensional Rayleigh law   总被引：2，自引：0，他引：2  

H. Markert  A. Lehmann 《Geophysical Journal International》1996,127(1):201-214

Rayleigh hysteresis, as defined by the well-known Rayleigh relations, has been observed not only when magnetization of pyrrhotite-bearing KTB-samples is measured in parallel to a weak dc magnetic field, but also in experiments where field and measuring directions have been adjusted strictly perpendicularly to each other. Nine-tupels of independent Rayleigh hysteresis loops could thus be compiled. Their characteristic coefficients X ^ijk of initial susceptibility together with the Rayleigh loss coefficients α^jk have been proved to determine completely the samples' weak-field magnetic anisotropy. Interpreting the coefficient matrices ( X ^ijk) and (α^jk) as the tensor of initial susceptibility and the Rayleigh tensor, respectively, generalization of the isotropic Rayleigh relations in terms of corresponding tensor relationships has been suggested for the anisotropic case. Application to the KTB samples showed 3-D Rayleigh hysteresis measurements to be an excellent tool for rock magnetic analysis in terms of ore content and crystalline texture. In particular, a magnetocrystalline double texture of the basal planes of pyrrhotite precipitates and their [1120] directions of easy magnetization have been clearly detected. Surprisingly, the welt-known theorem α= const. X ²_I, formulated by Néel (1942) for the isotropic case, has been found to hold true even in tensor generalization (α_jk) = const ( X ²_jk). To reach sufficient resolution for the measurements performed, a sensitive vibrating coil magnetometer (VCM) has been developed.  相似文献   

Unsiting Nuclear Power Plants: Decommissioning Risks and Their Land Use Context*     

Martin J. Pasqualetti  K. David Pijawka 《The Professional geographer》1996,48(1):57-69

Nuclear power plant siting provided the first significant public opportunity to examine nuclear safety and to affect nuclear policy. These discussions were prompted and fueled by perceptions of nuclear risk. Now, as we begin the process of nuclear decommissioning, we are finding that power plant removal—unsiting–is also likely to attract public interest. This paper presents a preliminary survey of how we are likely to react to this emerging theme, applying these findings within a land use context to see if it is likely to produce issues salient to the public. In so doing it also examines how these issues could affect decommissioning timing and type. It suggests that the most likely prospect is that power plants will remain on the landscape long after they are closed.  相似文献   

覆盖层下三维异常体对垂直磁偶极源的电磁响应     

李守春  李春祥  张伯军 《吉林大学学报(地球科学版)》1996,(4)

针对地下半空间存在三维异常体及覆盖层情况，计算了垂直磁偶极子的场，计算结果表明σ１与σ２接近时，覆盖层影响减小；σ１增加时覆盖层影响增大；对于不同的σ２／σ１值，场幅值对高频（ｆ≥２ｋＨｚ）和低频（ｆ≤１０Ｈｚ）都明显减小，只有在２ｋＨｚ≥ｆ≥１０Ｈｚ之间，场幅值可达最大。还表明垂直磁偶极子的场具有较强的岩性识别和分层能力  相似文献   

核技术找水二十年     

梁锦华 《物探化探计算技术》1996,(S5)

本文简要地叙述了核技术找水的研究历程 ,阐明了含水构造放射性异常机制和规律探索对方法技术发展的影响。列出了部分县市的实用数据 ,表明在推广应用中 ,核技术找水的成功率高于 75 %。  相似文献   

石油重磁资料处理解释系统在微机上的实现     

吴健生  王家林 《物探化探计算技术》1996,18(1):35-46

微机技术的发展和石油重磁勘探的需要促使了石油重磁资料微机处理和解释系统的建立。系统由输入、输出辅助子系统、重磁场分离和转换子系统及五个反演解释子系统八部分组成。五个反演解释子系统针对重磁力方法在油气勘探中所能解决的地质问题的类型不同而设计。计算模块的选择注意到方法的有效和适应，地球物理综合解释的需要及平面与剖面、定量正演与反演相结合的重要性。实际应用例子说明系统建立的成功和有效  相似文献   

Radon,Lung Cancer Risk and Environmental Geology in Gejiu Area     

卢伟  王任重等 《中国地球化学学报》1997,16(3):278-282

The incidence of lung cancer in the Gejiu area of Yunnan Province ranks the first in the world.The radon level(indoor,soil) was measured in the Gejiu area by the SSNTD method from 1990 to 1996,The result indicates an extensive high-level of indoor radon in that area though U and Th are lower in local limestones,The indoor radon level of houses located in the geologic fault zone is 6 times high that 2km far from the fault zone.The reason probably is that the radon level of soil in the fault is 6-8 times high that 1 km far from the faults.our data indicate that a lower range of radon levels,0-100Bq.m^-3,exists in healthy families.However,a higher radon level,over 800 Bq.m^-3,is often found corresponding to that of cancer patients‘ homes(the house-owners are suffering from either lung cancer or leukaemia or liver cancer),Obviously,an increase in lung cancer incidence follows an increase in indoor radon level,The risk of cancer induced by indoor radon is no longer an inference,but a fact.  相似文献   

我国磁法勘探的研究与进展   总被引：7，自引：2，他引：7       下载免费PDF全文

管志宁 《地球物理学报》1997,40(Z1):299-307

简要概述了我国磁法勘探50年来的研究与进展，主要包括：地面、航空与海洋磁测工作，磁力仪研制与生产，磁异常处理与转换技术，磁异常解释理论与方法，岩石磁性研究，磁法勘探在基础地质研究、固体矿产勘查、油气勘查和其他领域中的应用．  相似文献   

克服低纬度化磁极困难的有效方法     

姚长利  管志宁 《吉林大学学报(地球科学版)》1997,(2)

低纬度地区（尤其是磁赤道附近）磁场化极是长期以来没有很好解决的问题。这里提出的方法只时常规化极稍加改进，通过时化极因子的频点偏移，避开无界点，使化极结果改善很大，甚至在赤道上也可以化极。它既有很高的精度，又因仍是在频率域内进行，故计算方便、快速，非常适合大面积的资料计算  相似文献   

马山金（硫）矿床地球物理地球化学找矿模式     

马敦昶 《地质与勘探》1997,33(3):43-47

根据矿床的地球物理地球化学异常特征，磁异常与金矿体的关系，地球化学异常及其垂向分带规律，归纳出矿床地球物理地球化学找矿模式和找矿标志。  相似文献