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Faisal S.Al-Huzaim 《世界地质(英文版)》2003,6(2)
The Jabal Mabal-prospect of Al Bayda area is covered by meta-volcano sedimentary rocks. The importance of the study area comes from previous studies, which proved that the area has mineralization zones at the periphery of Jabal Al-Mabal. These mineralized zones lie along northwest-southeast shear zones, which occur inside the meta-volcanic rocks. The previous studies concluded that the mineralization was mostly associated with sulphides, especially at the reduction zones. These sulphides give a good response to electrical or electromagnetic techniques. The present study uses electrically induced polarization and Genie electromagnetic surveys to explore the extension of the mineralization zones at the subsurface.
The self-potential (SP) technique shows numerous of mineralized zones. Most of these zones are distributed in the southern area along the contact between the quartz and gabbro. The induced polarization (IP) method has been applied on the selected profiles to delineate the subsurface contact between calcite, gabbro and quartz in Al-Jarra Valley and to calculate the shape and depth of the mineralization zones in the subsurface along these profiles. The Genie electromagnetic survey, which has been applied on selected profiles, delineated some weak mineralization occurrences corresponding to the shear zones. The integration of the results obtained using these three techniques, in addition to the different ground geophysical methods previously used, makes it possible to determine the most appropriate zones for development of exploration at the area of investigation. 相似文献
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Intraday variations of compact extragalactic radio sources in flux density and po- larization are generally interpreted in terms of refractive scintillation from the continuous interstellar medium of our Galaxy. However, continuous polarization angle swings of～180° (for example, the one observed in the QSO 0917 624) could not be interpreted in this way. Qian et al. have shown that the polarization angle swing observed in the QSO 1150 812 can be explained in terms of focusing-defocusing effect by an interstellar cloud, which occults two closely-placed polarized components. Here we further show that the polarization angle swing event observed in the QSO 0917 624 can also be explained in this way. We also found evidence for the cloud eclipsing a non-polarized (core) component during a short period out- side the swing. A particular (and specific) plasma-lens model is proposed to model-fit the polarization swing event of 0917 624. Some physical parameters related to the plasma-lens and the source components are estimated. The brightness temperatures of the two lensed components are estimated to be ～1.6×1013 K. Thus bulk relativistic motion with a Lorentz factor less than ～20 may be sufficient to avoid the inverse - Compton catastrophe. 相似文献
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将ICA（Independence Component Analysis）消噪原理应用于合成孔径雷达抗噪声干扰技术中,用噪声信号和受到干扰的SAR回波数据作为扩展的虚拟观测信号,对扩展的多维加噪观测信号进行分离, 得到源雷达回波信号, 从而实现噪声的有效消除.通过对条带式SAR点目标成像进行仿真试验, 结果表明这种消噪方法在消除SAR噪声干扰中是有效的. 相似文献
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