Details of the Abstract
| Title of paper | MT image of an orogenic copper-gold deposit at the edge of Kongo craton, Namibia |
| List of authors | Becken, M., Treppke, H., Joone, C., Scheunert, M. |
| Affiliation(s) | University of Münster, University of Münster, Ongwe Minerals, TU Bergakademie Freiberg |
| Summary |
Orogenic copper gold deposits have been widely found to be associated with lithospheric electrical conductors. Recent work has suggested that precipitation of graphite during mantle-sourced fluid ascent represents the genetic link between lower crustal conductors and surface mineralizations. This renders the magnetotelluric (MT) method a valuable tool to characterize orogenic copper-gold mineral systems. We present the results of a 50 km MT profile across the edge of the Kongo craton near Khorixas, Namibia. The area is currently being explored for gold and auxiliary minerals using geological mapping and rock sample analysis and has shown to host significant concentrations of gold up to 2-50 g/t. However, questions remained to as the type of mineral system responsible for enhanced gold concentrations. MT was used in this context to test for the existence of lower crustal conductivity anomalies and crustal pathways. The final model displays a pronounced conductivity anomaly with conductivities in excess of 1 S/m at mid-to-lower crustal levels, reaching to depths of about 10 km below the mineralization zone. Individual pathways connecting the deep conductivity anomaly with the surface mineralization cannot be imaged, but the audio-MT grid data reveal localized, moderate near-surface conductors, possibly associated with alteration zones. The model is thus overall consistent with MT images of orogenic copper-gold deposits elsewhere, suggesting that the gold occurrences encountered in the study area belong to this type of mineral system. |
| Session Keyword | 3.0 EM methods for exploration (geothermal, mineral resources, etc.) |
| File upload |
3.0_mt_image_of_an_orogenic_c_becken.pdf
|