3D Seismic Imaging of the Ghost-Carbon Leader Reef of the World's Deepest Gold Mine - Mponeng Gold Mine, South Africa

Abstract

The re-interpretation of the old 3D seismic data from the world’s deepest gold mine of the Witwatersrand basin, have proven to be effective in enhancing the detection of fault zones and unstable lithologies that are potential mining hazards. Most of the structures identified seem to offset the gold-bearing horizons such as the Ventersdorp Contact Reef (VCR) and Carbon Leader Reef (CLR) with throws below seismic resolution limit (equivalent to one-quarter dominant seismic wavelength (λ/4)). To derive or ghost the seismically transparent Carbon Leader Reef model, we used more than 2000 drillholes that intersect the CLR (within the Central Group), VCR (top of the Central Rand Group) and Crown lava (top of the West Rand Group). The final ghosted CLR shows a very consistent dip with the VCR and Crown lava. The model also shows that 60% of the structures imaged at the VCR level at 2-3 km depth continue and displace the ghosted-CLR at 3.5-4.5 km depth in a similar manner. This model represents the gross-structural architecture that was formed following the massive Platberg age extension on the first-order scale structures.