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An integrated geophysical study of the lithospheric structure beneath Libya.

机译：利比亚下方岩石圈结构的综合地球物理研究。

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摘要

This doctoral dissertation constitutes an integrated geophysical investigation of the lithospheric structure in the region of Libya. It is separated into three sections, each of which will be submitted to different scientific journals for publication. In the first part of the study, I utilized a seamless mosaicking approach based on the commercial Environment for Visualizing Images (ENVI) software package to create mosaics of two geologically interesting portions of Libya. In this study I present a step by step method of mosaicking Landsat 4 satellite images. Firstly, I performed histogram matching to give images the same color scale, then I used a cutline feathering technique to blend suture areas and finally I overlaid the images to form the two mosaics. The resulting mosaics were then combined with structural features and the seismicity map of the area. The resulting mosaics were proven to be useful in identifying recently active faults and shows great potential for verification of other faults and in natural hazard assessment.; For the second portion of my research, I made use of over 6,000 free air corrected gravity data in conjunction with other geological and geophysical data to develop a 3D density model for northern Libya. I used a gravity modeling program (SURFGRAV) to develop the 3D density model by manipulating it to accurately predict large areas of Free Air anomaly shown in the data. The residual gravity anomaly values were calculated by subtracting predicted Free Air anomaly from the observed Free Air anomaly. The results were satisfactory for uplifted areas of Libya while there were significant mismatches in basin areas. The density model was iterated and used as a starting model for the final portion of the study.; In the last part of this research, I used the Nafe-Drake relationship along with other geological data to convert the 3D density model to a 3D velocity model (LIBYA3D) for the region. Two earthquakes having source receiver paths sampling much of the modeled area were used to perform 1D and 1.5D validation tests, and the results were compared to those from previous studies. The results showed that the new 3D velocity model is valid and superior to the global model. However, until there is sufficient earthquake data acquired, and we are able to perform 2D and 3D modeling we may not be able to see the true improvement of LIBYA3D as compared to the other regional models.
机译：该博士论文构成了对利比亚地区岩石圈结构的综合地球物理研究。它分为三个部分，每个部分将提交给不同的科学期刊进行出版。在研究的第一部分中，我使用了基于商业化可视化图像环境（ENVI）软件包的无缝镶嵌方法来创建利比亚两个地质有趣部分的镶嵌图。在这项研究中，我提出了逐步拼接Landsat 4卫星图像的方法。首先，我执行直方图匹配以使图像具有相同的色标，然后我使用剪切线羽化技术来混合缝合区域，最后覆盖图像以形成两个镶嵌图。然后将生成的镶嵌图与结构特征和该地区的地震图结合起来。事实证明，由此产生的镶嵌图可用于识别近期活动的断层，并具有验证其他断层和进行自然灾害评估的巨大潜力。在我的研究的第二部分中，我利用了6,000多个自由空气校正重力数据以及其他地质和地球物理数据，为利比亚北部开发了3D密度模型。我使用重力建模程序（SURFGRAV）通过操纵3D密度模型来准确预测数据中显示的大面积Free Air异常。通过从观察到的自由空气异常中减去预测的自由空气异常来计算残余重力异常值。对于利比亚隆起地区，结果令人满意，而流域地区存在明显的不匹配。迭代密度模型，并将其用作研究最后部分的起始模型。在这项研究的最后一部分中，我使用了Nafe-Drake关系以及其他地质数据，将区域的3D密度模型转换为3D速度模型（LIBYA3D）。使用两次地震的源接收器路径对大部分建模区域进行了采样，以进行一维和1.5D验证测试，并将结果与​​先前研究的结果进行了比较。结果表明，新的3D速度模型是有效的并且优于全局模型。但是，在获得足够的地震数据之前，我们能够执行2D和3D建模，与其他区域模型相比，我们可能看不到LIBYA3D的真正改进。

著录项

  • 作者

    Brown, Wesley A.;

  • 作者单位

    The University of Texas at El Paso.;

  • 授予单位 The University of Texas at El Paso.;
  • 学科 Geology.; Geophysics.; Geodesy.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 154 p.
  • 总页数 154
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地球物理学;大地测量学;
  • 关键词

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