THE SINGO GRANITE, MINERAL OCCURRENCES AND RING COMPLEXES UGANDA

Recently acquired high resolution aeromagnetic data was used to investigate the structure of the Singo granite in central Uganda which hosts hydrothermal economic minerals such as gold and copper. The spatial distribution of these deposits is not well known and current mine workings are limited on the western margins of the intrusion. Our objective was to investigate the relationship between the structure of the granite and mineral occurrences as an aid to future exploration programs. The data flight height was 80 m with a line spacing of 200 m. Analytical signal, vertical and tilt derivative filters were applied to the reduced to the equator data to enhance the structure of the granite and contact with the surrounding country rocks. In addition, a three-dimensional model was produced using Geosoft’s Voxi module. The filtered data provided an unprecedented view of nine ring complexes with diameters ranging from 2.5 to 14 km and high magnetization at the margins with non-magnetic centers. The 3-D inversion revealed near vertical walls of the ring complexes extending to depths of about 7 km suggesting a stopping and assimilation emplacement process. The magnetic anomaly in the NE and SE edge of the granite where porphyries were detected range between (-516 to 125) nT. Identification of these new porphyry sites suggests potential areas for mineral exploration. Our results also suggest that high resolution aeromagnetic data is crucial for mapping ring complexes and understanding their modes of emplacement.