高密度激发极化法测量在峪耳崖金矿区的应用     

徐德利  于爱军  李文良  卿敏  陈孝强  马德锡  樊战军 《物探与化探》2007,31(Z1):89-93

运用美国生产的高密度电法仪器对峪耳崖金矿区16~28线进行了测量。该仪器可同时测得视电阻率和视充电率2种数据,并可自动成图和地形改正。通过高密度电法工作圈定了地表较浅部的矿化异常区,除主要矿化异常赋存于岩体接触带外,在灰岩中也发现高极化异常区,表明在灰岩地层内也存在金属硫化物矿化现象,这为下一步找矿工作提供了新的思路和方向。通过钻探结果确定该矿区异常区有2种类型,即高阻高充电异常和低阻高充电异常,主要分布在岩性的接触带附近,尤其是内接触带。  相似文献   

Electron density distribution of FeTiO<Subscript>3</Subscript> ilmenite under high pressure analyzed by MEM using single crystal diffraction intensities     

Takamitsu Yamanaka  Yutaka Komatsu  Hironori Nomori 《Physics and Chemistry of Minerals》2007,34(5):307-318

Many of ilmenites ABO₃ compounds bearing transition elements have semiconductive, ferroelectric and antiferromagnetic properties. The high-pressure diffraction studies of FeTiO₃ have been conducted up to 8.2 GPa using synchrotron radiation in KEK at Tsukuba with diamond anvil cell. The compression mechanism of FeTiO₃ ilmenite has been investigated by the structure refinements converged to the reliable factors R = 0.05. The deformations of the FeO₆ and TiO₆ octahedra were reduced with increasing pressure. In order to elucidate the electric conductivity change with pressure, electron density distribution of ilmenite have been executed by maximum entropy method (MEM) using single-crystal diffraction intensity data. MEM based on F _obs(hkl) of FeTiO₃ clearly shows electron density in comparison with the difference Fourier synthesis based on F _obs(hkl) − F _calc(hkl). The radial distribution of the electron density indicates electron localization around the cation positions. The bonding electron density found in bond Fe–O and Ti–O is lowered with pressure. The isotropic temperature factors B _iso become smaller with increasing pressure. Nevertheless the thermal vibration is considerably restrained by the compression, the electric conductivity is enhanced with pressure. Neither charge transfer nor electron hopping between Fe and Ti along the c axis in FeTiO₃ is plausible under high pressure. But the electric conductivity due to electron super-exchange in Fe–Fe and Ti–Ti has been clarified by the MEM electron density distribution. The anisotropy in the electric conductivity has been clarified.  相似文献   

Statistical Segmentation of Geophysical Log Data     

Danilo R. Velis 《Mathematical Geology》2007,39(4):409-417

Stationary segments in well log sequences can be automatically detected by searching for change points in the data. These change points, which correspond to abrupt changes in the statistical nature of the underlying process, can be identified by analysing the probability density functions of two adjacent sub-samples as they move along the data sequence. A statistical test is used to set a significance level of the probability that the two distributions are the same, thus providing a means to decide how many segments comprise the data by keeping those change points that yield low probabilities. Data from the Ocean Drilling Program were analysed, where a high correlation between the available core-log lithology interpretation and the statistical segmentation was observed. Results show that the proposed algorithm can be used as an auxiliary tool in the analysis and interpretation of geophysical log data for the identification of lithology units and sequences.  相似文献   

塔克拉玛干沙漠腹地两种灌木有效根系密度分布规律的研究     

单立山  张希明  魏疆  闫海龙  花永辉  张建军 《干旱区地理》2007,30(3):00-405

在塔克拉玛干沙漠腹地通过分层分段挖掘法对滴灌条件下多枝柽柳(Tamarix ramosis-sima)和梭梭(Haloxylon ammodendron)幼苗根区有效根长密度和有效根重密度空间分布进行了研究。结果表明:梭梭幼苗平均有效根系密度为多枝柽柳幼苗的3倍左右。在垂直方向上,两种灌木的有效根系密度的变化因树种而异,多枝柽柳幼苗随土层深度的增加呈指数递减,而梭梭幼苗随土层深度的增加呈单峰型曲线。在水平方向上,两种灌木幼苗有效根系密度均随距离植株基径距离的增加呈指数递减。非线性参数拟合分析表明:采用RD=eA BX CZ函数模型能较好地反映滴灌条件下多枝柽柳幼苗的有效根系密度的空间分布。  相似文献   

Monitoring the three-dimensional ionospheric electron density distribution using GPS observations over China   总被引：3，自引：0，他引：3  

Debao Wen  Yunbin Yuan  Jikun Ou 《Journal of Earth System Science》2007,116(3):235-244

In this paper, an IRI model assisted GPS-based Computerized Ionospheric Tomography (CIT) technique is developed to inverse the ionospheric electron density (IED) distribution over China. Essentially, an improved algebraic reconstruction technique (IART) is first proposed to reconstruct the ionospheric images with high resolution and high efficiency. A numerical experiment is used to validate the reliability of the method and its advantages to the classical algebraic reconstruction technique (ART). This is then used to reconstruct the IED images using the GPS data in China. The variations of the IED during magnetically quiet and disturbed days are reported and analyzed here. Reconstructed results during magnetically quiet days show some prominent ionospheric features such as the development of equatorial anomaly and the tilt of ionization crest. Meanwhile, ionospheric storm phase effects and disturbed features can also be revealed from the reconstructed IED image under storm conditions. Research shows that the positive storm phase effects usually happen in southern China, and the negative storm phase effects mainly occur in northern China. The equatorial anomaly crest moved to the north in the main phase of the storm. Ionosonde data recorded at Wuhan station provides the verification for the reliability of GPS-based CIT technique.  相似文献   

基于解析方法计算频散层状介质的探地雷达响应     

王卓  曾昭发  张代国  郑圣谈  徐铮伟 《吉林大学学报(地球科学版)》2007,(Z1)

考虑频散介质的电磁波传播,采用Cole-Cole公式建立频散模型。只考虑介质的介电常数随外加电磁场频率的变化,采用高密度采样滤波算法,模拟层状介质的雷达响应,从中可以看出频散介质对雷达波的衰减影响。  相似文献   

二度半长方体组合模型的重力模拟退火反演   总被引：6，自引：4，他引：6       下载免费PDF全文

于鹏  王家林  吴健生 《地球物理学报》2007,50(3):882-889

针对重力异常反演的现状,采用矩形单元体网格剖分的二度半体组合模型,模拟任意的多层密度界面或形体,实现了重力正演.该建模方法适应性强,适合于实际工作中常见的密度横向变化的复杂模型.使用改进的全局寻优的快速模拟退火算法,对重力异常进行反演,结合这种灵活的密度建模方法,反演过程中只需要反演各矩形单元体的密度参数,即可同时得到地质体的界面或形态以及密度值分布.通过复杂界面和形体的模型试验,证明了方法的效果.在江苏下扬子地质构造复杂区的实际应用说明,在地震等先验信息约束下,该重力反演方法提高了反演精度并减少了多解性,可有效解决古生界泥盆系-志留系目的层分布等地质问题.  相似文献   

青藏高原班公湖－怒江缝合带域岩石密度结构及意义   总被引：4，自引：1，他引：4       下载免费PDF全文

曹忠权  张智  田小波 《地球物理学报》2007,50(2):523-528

班公湖-怒江缝合带分隔了青藏高原拉萨地块和羌塘地块, 该带域岩样采集与分析对于该区地球物理资料深化解释、拉萨地块和羌塘地块拼贴碰撞过程的理解等均具有重要意义. 1995年在措勤盆地中采集了3条剖面、从奥陶纪至第四系不同地质年代地层岩石标本共计2500块. 通过岩石密度测试, 获得了研究区不同地质年代岩石密度测量结果. 结果表明, 岩石由老到新密度变化范围为278～253 g/cm3；各相邻地质时代间岩石密度差基本上为010 g/cm3, 白垩与侏罗、二叠与三叠之间岩石密度差最大为012～013 g/cm3 在措勤盆地内不同构造单元间岩石密度存在明显的纵横向非均一性.  相似文献   

有关Kanai-Tajimi模型的统计特征分析     

张菊辉 《世界地震工程》2007,23(1):156-160

选择金井清过滤白噪声模型,采用留数定理推导出K-T谱激励的自相关函数表达式,并在此基础上利用相关函数法分析出K-T谱激励下的平稳反应,并采用功率谱方法加以验证。这些结果可为结构随机地震反应时域分析和抗震可靠性评估提供基础。  相似文献   

强震地面运动超随机特性的几点注记     

徐国栋  周锡元  闫维明 《地震工程与工程振动》2007,27(1):7-15

本文详细论述了功率谱与功率谱密度、平方和SS与平方平均值MS的适用范围及物理意义,比较深入地分析了平稳和非平稳加速度时间历程的统计特征,通过引入时域包线获取特定相位的方法,考虑了非平稳特性。本文基于非平稳时间历程,在不考虑频率非平稳性的基础上,提出了设计地震动三要素:(1)平方和SS;(2)归一化自相关函数或其对应的功率谱;(3)地震动时域包线.本文提出了在设计地震动合成中考虑超随机特性的实用方法,并指出地震动的超随机特性(即归一化功率谱的锯齿状波动部分,或归一化自相关函数的随机噪声部分)与相位的随机性是地震动随机特性的两个重要方面。本文将地震动的统计分析直接建立在非平稳时间历程的基础之上,从而避开了要对地震动进行平稳化处理的困难。这样提取出的地震动统计特征完全是以真实地震动记录为基础的。应用这些统计特征,可模拟出符合统计要求的基于非平稳时间历程的设计地震动。最后本文还讨论了工程上常用的将反应谱近似转换为功率谱的转换式的一些缺陷。  相似文献