An Integrated Approach to Characterise the Subsurface Using Near Surface Geophysical Methods

Abstract

Summary One of the most precarious aspects of mining economics for underground mining includes the proper management of groundwater. Appropriate mine water management design may minimise inefficient and expensive dewatering schemes due to a thorough understanding of the groundwater storage and flow direction of the mine. The area of interest, Tharisa Mine, is located on the southwestern limb of the Bushveld Igneous Complex (BIC) that hosts world-class platinum group metal deposits in South Africa. The aquifers of the BIC are classified as fractured crystalline and intergranular systems. This research aims to delineate the near-subsurface architecture and fluid migration pathways linked to the potential water source in the study area. This is achieved by using stable environmental isotopes (δ18O and δ2H) and radioactive isotopes of water (δ3H). Further, geophysical methods comprising Electrical Resistivity Tomography (ERT) and Multichannel Analysis of Surface Waves (MASW) assist in delineating fluid migration pathways and lineaments. Integration of the hydrogeological and geophysical data delineated fluid migration pathways and lineaments. The main sources for water in the mine include mixing of surface/rain water with connate/deep water sources, recycling of water via lineaments and tailing dam seepages.