The use of Borehole Radar for the delineation of thin tabular orebodies ahead of mining

Abstract

A significant portion of South Africa?s current gold resources come from the Ventersdorp Contact Reef (VCR). The VCR is a tabular orebody, generally less than 1.2m thick. Slopes, terraces and faults impact on VCR geometry. Gold is generally concentrated in palaeochannels, corresponding to terrace elevations. Conversely, slopes are generally associated with lower gold grades. To be able to site support pillars, such that they correspond with lower gold grade slope areas, has significant financial benefit. The geophysical challenge is, thus, to model the reef geometry prior to mining in order to facilitate optimal ore extraction. Borehole radar has proven to be applicable for mapping topography on the VCR. In this paper a case study is presented where radargrams and 3D visualization from three boreholes show continuity of geometrical features on the VCR target horizon. The improved confidence in the geological model has an immediate impact on resource estimation and mine planning with immediate financial benefits.