Structural Analysis

Several case studies showing how to carry out a structural analysis are presented in this chapter. Firstly, the principal decisions that have to be made by the geostatistician are reviewed. Are the data stationary? Are they isotropic? Should we work with the variables themselves or their accumulations? Should the study be carried out in 2D or 3D?The first case study is a relatively simple 3D study of an iron ore deposit. As the horizontal and vertical variograms are well structured, it provides a clear illustration of a straightforward variographic analysis. The second study concerns an Archaean gold deposit that is being mined by opencut methods. So the grades of closely spaced blastholes are available in addition to the more widely spaced exploration drillholes. The third deposit presented is a sedimentary gold deposit with a periodic variogram in one direction because the gold was deposited by stream action. In contrast to the other two deposits, this one is only about im thick and so the study was carried out in 2D rather than 3D.