MAGNETIC AND GRAVITY IMAGING ON KOPJESKRAAL FARM WITHIN THE VREDEFORT IMPACT STRUCTURE, SOUTH AFRICA

This project serves to investigate subsurface anomalies and groundwater potential on Kopjeskraal Farm located approximately 6 km northwest of Parys, South Africa within the Vredefort impact structure. The Vredefort impact structure, located in South Africa, is the Earth’s oldest recorded impact structure. An asteroid struck the Earth two billion years ago near the present day town of Parys. Shockwaves followed this impact that deformed and restructured the underlying stratigraphic layers. The research area is near the center of the dome due to its proximity to Parys. The granite dominant central dome is bounded by Dominion Group lavas and quartzite. There appears to be a large negative anomaly extending from northeast to southwest in the magnetic survey. Using the Scintrex CG-5 gravimeter we were able to determine the depth of the bedrock and the overburden. We performed magnetic surveys with the G-858 Cesium vapor “MagMapper” and the G-856 proton precession magnetometers. Forward modelling analysis was utilized in order to form our hypothesis that the anomaly is likely to be a weathered fracture zone. The gravity survey showed a southeast dipping gradient. Two methods do not contradict one another; however, gravity survey results are much less detailed than the magnetic survey. Groundwater potential is likely due to the intense faulting and fracturing resulting from the impact.