b'FeatureDiscovery and geophysics of the Khamsin depositFigure 10.1. CDI depth slice: 100m. Units are mS/m. The black outlineFigure 10.3. CDI depth slice: 600 m. indicates the dense ovoid in Figure 5.2.Figure 10.2. CDI depth slice: 450 m Figure 10.4. CDI depth slice: 900 mmight seem more probable than a palaeochannel at that depth. Interpretations will no doubt converge as more information becomes available. This feature seems not to have been drilled, and, if the low conductivity means weakly saline or even potable water, it might represent a resource of value to local pastoralists and/or for mine development. The lobe of elevated conductivity associated with Plate 9 in Figure 12.1 (near 730000E, 450 m depth) seems to be about all that we can expect from the ore at Khamsin under such difficult survey conditions. In an early model a single plate covered the lateral extent of the ovoid in Figures 5.2 and Figure10.2, but when divided into Plates 5 and 9, the small separation, with resistive Plate7, was found to replicate better the dip in conductivity that follows the linear gravity low.A numerical experiment shown in Figure12.2 indicates that ifFigure 11. Channel amplitudes and CDI for Line 6547800N with profiles of Plate 1, used to simulate conductive cover, is eliminated thengravity (red), magnetics (blue) and topography (green).Plates 5 and 9, used to simulate the vicinity of the ovoid, would both be revealed in the CDI. It seems safe to conclude that ato require a dispersive conductivity in order to generate the conductive zone in the cover is masking the TEM response fromlow (blue) values under them in Figure 12.2, but the effect is a significant portion of the deposit. insufficient when compared to the data. This may mean that Visual inspection of drill core suggests rock of relatively lowthe best combination of Cole-Cole parameters has not yet been porosity (to the exclusion of conductive brines?) with sulphidefound, or, that the deeper country rocks under the deposit are disseminationsa situation often recognised as causingless conductive. When Plates 5 and 9 in Figure 12.1 are made polarization effects in TEM data (Flis et al.1987, Hodges andnon-polarizable (m=0) the conductivity low beneath them Smith, 1997). The response of Plates 5 and 9 in the model seemsdisappears (not shown). FEBRUARY 2024PREVIEW 49'