Figure 9. Wireframe constructed for the Kimberley Reef, Evander basin showing the extent of the lease area and mined out area (red and dark grey). Contours are in metres below datum (1 829 masl).

Figure 10. The pre-Kimberley Reef geology of the Far East Rand.

Figure 12. The geology of the pre-Kimberley Reef surface in the Evander area. The dips refer to the angles of unconformity between the Kimberley Reef and the footwall.

Figure 19. Palaeocurrent directions measured in the Kimberley Reef at Evander (K.A.M. Tweedie, 1968 ; E.B. Tweedie, 1981 ).

Figure 20. Palaeocurrent directions in the hangingwall (HW2) of the Kimberley Reef (reproduced from E.B. Tweedie, 1981 ).

Figure 21. Clast compositions and palaeocurrent directions in the Kimberley Reef of the Far East Rand (E.B. Tweedie, 1981 and 1986 ; Button, 1968 ; Armstrong, 1965 ; de Jager, 1964 ; Muntingh, 2016, pers. comm.). This map straddles the region between Secunda, Heidelberg and Delmas

Figure 24. Map showing mean pebble sizes in the Kimberley Reef as observed in boreholes by mine geologists.

Figure 25. Kimberley Reef isopach map. The isopachs extend beyond the subcrop due to the presence of narrow fault blocks and the smearing effect of the contouring software.

Figure 26. Percentage quartzite partings in the Kimberley Reef.

Figure 34. Spatial variation of the U/Au ratio in the Kimberley Reef at Evander.

Figure 35. Carbon occurrences in the Kimberley Reef.

Figure 36. Gold accumulation in relation to the type of carbon in the Kimberley Reef.

Figure 27. A schematic section across the Evander Goldfield showing the thickness of the Kimberley Reef and its pebble content in relation to the regional folding and footwall lithologies. The interval between the base of the Booysens Shale and the Kimberley Reef is approximately 150 m

Figure 22. The abundance of jasper and banded iron formation (BIF) clasts in the Kimberley Reef at Evander ( Hirdes, 1979 ).

Figure 11. Geological cross section from the East Rand to Evander, assuming that the Kimberley Reef is horizontal. Note the vertical exaggeration.

Figure 3. Polished slabs of reef conglomerates. ( a ) Clast-supported pebble conglomerate (Kimberley Reef). Clasts are mainly made of vein quartz. ( b ) Climbing ripple cross-laminated pebbly sandstone (Main Reef Leader, Geldenhuis Deep Mine). Most sand-sized grains are made of detrital pyrite

Figure 4. ( a ) Concentration of sand-sized carbonaceous grains (“fly-speck carbon”) forming a 2-cm-thick carbon seam in sandstone (Kimberley Reef, Daggafontein Mine). Note carbonaceous grains both above and below the carbon seam disseminated or concentrated in laminae. ( b ) Sand-sized

Figure 2. Schematic geological map of faults and mafic dykes in the Cooke Section at the level of the Kimberley Reefs. This complex array of faults and dykes is located in the footwall (eastern block) of the West Rand Fault Zone and forms a macroscopic breccia.

F ig . 1. Schematic map of the Witwatersrand Basin and location of the main goldfields: 1 Evander, 2 East Rand, 3 Central Rand, 4 West Rand, 5 Carletonville, 6 Klerksdorp, 7 Welkom. The stratigraphic column shows the position of the Kimberley Reef, from which the PGM were taken for our study.