Figure 1

Kopanang-Vaal system. (A) Map of Kopanang Mine showing dykes (green lines) fault zones (blue lines) and mining tunnels, stopes (grey), Vaal River (light blue) and property boundaries (black lines). Red box is inset outline for B. Yellow box is inset outline for C. (B) A simplified geological map of the mine level showing the location of the borehole (red arrow) with respect to two intersecting fault zones (outlined in blue), one striking WSW/ENE and a younger fault zone striking SW/NE and off-setting the old fault zone, showing the dykes (green), mining tunnels (grey lines), and the borehole (brown line with blue dots). The open red arrow marks position of the drilling cubby where the borehole is accessible from the tunnel. (C) The possible direction of fissure water flow along the fault zone and towards the borehole (red arrows). Also shown is the position of the Vaal River overhead (light blue) hypothesized to recharge the fissure fluid. (D) Google Earth image of the region showing the location of Kopanang Mine and the vertical extrapolation of the location of the borehole (red dot) and the fault zones. Sampling sites of Vaal River water and mud occur near Orkney bridge (yellow X’s). The open white arrow points to an isolated patch of vegetation sitting on top of a ridge with the WSW/ENE fault zone to the north and the SW/NE fault zone to the south. Red dot marks position of the drilling cubby where the borehole is accessible from the tunnel. (E) Photograph of the borehole in the cubby. Scale bars: (A) 1 km, (B) 100 m, (C) 250 m, (D) 1 km, (E) 10 cm. Map data: Google, Digitalglobe/CNES/Airbus.