Development of joint moving-interface inversion methodology for geophysical DC resistivity and time-domain EM data

铀矿开采对加拿大的经济很重要，找到更多的铀矿床开采对这个行业的未来至关重要。加拿大的大多数铀矿都位于萨斯喀彻温省北部的阿萨巴斯卡盆地。铀矿体位于地球表面下数百米处，位于深部基岩中的断裂带和位于基岩顶部的沉积岩之间的交界处。基岩中的这些断裂带通常含有石墨，这使得它们与周围的岩石相比，具有较好的导电性。电力和电磁测量对地下这种导电特征的存在很敏感，因此在阿萨巴斯卡盆地寻找新的铀矿体方面发挥着重要作用。这类调查的数据包含有关石墨质断裂带的位置、深度、大小和导电性的信息。从这些测量中确定断裂带的位置等越好，所需的钻探就越少，这可以显著降低勘探过程的费用。要从调查数据中得出这一信息，需要使用计算机建模和解释技术。然而，目前的技术并不适合于石墨质断裂带的尖锐、独特的性质，而是产生了断层的模糊、模糊的表示。该项目将扩展以前为重力和磁性数据开发的一种新的计算机解释方法，以包括电气和电磁数据。这一新方法通过离散相邻岩石类型之间的界面，然后移动和调整这些界面，从而指定地下特征，以便为该地下模型计算的地球物理测量数据与测量数据相匹配。这与目前的方法不同，当前的方法是将亚表面划分为许多小单元，并求出所有单元中的电导值，使得计算数据和测量数据之间的匹配良好，并且物理性质从一个单元到下一个单元的变化是平滑的。

Uranium mining is important to Canada's economy, and finding more uranium ore deposits to mine is criticalto the future of this industry. Most uranium ore deposits in Canada are to be found in the Athabasca Basin in northern Saskatchewan. The uranium ore-bodies are located hundreds of metres beneath the Earth's surface at the junction between fault zones in the deep basement rocks and the sedimentary rocks which lie on top of the basement rocks. These fault zones in the basement rocks often contain graphite, which makes them relatively good at conducting electricity compared to the surrounding rocks. Electrical and electromagnetic surveys are sensitive to the presence of such electrically conductive features in the subsurface, and so play an important role in the exploration for new uranium ore-bodies in the Athabasca Basin. The data from such surveys contain information about the location, depth, size and electrical conductivity of the graphitic fault zones. The better the location, etc., of the fault zones can be determined from these surveys the less drilling is required, which can significantly reduce the expense of the exploration process. To derive this information from the survey data requires the use of computer modelling and interpretation techniques. However, current techniques are not suited to the sharp, distinct nature of the graphitic fault zones, producing instead fuzzy, indistinct representations of the faults. This project will extend a new computer interpretation approach, previously developed for gravity and magnetic data, to include electrical and electromagnetic data. This new approach specifies the subsurface features by discretizing the interfaces between neighbouring rock types, and then moving and adapting these interfaces so that geophysical survey data computed for this model of the subsurface match the data measured in a survey. This is in contrast to the current approach, which is to divide the subsurface into many little cells and to find the values of electrical conductivity in all the cells such that the match between computed and measured data is good and that the variation of the physical property from one cell to the next is smooth.