Exploring relationships between geological structures delineated from high resolution geophysical data collected over 1:50,000 mapsheets 2229AB Mapungubwe and 2229AD Coila, Beit Bridge Terrane, Central Zone, Limpopo Belt, South Africa

[摘要] High resolution aeromagnetic and radiometric data covering the 1:50,000 mapsheets2229AB Mapungubwe and 2229AD Coila were collected by the Council for Geoscienceand interpreted in this study. Several generations of magnetised lineaments wereidentified and modelled as mafic dykes. North-northwest, east-northeast and east-westtrending lineaments occur in the pre-Karoo basement (~2.04 Ga to Dwyka) and east-westtrending lineaments predominate in Karoo sediments (<183 Ma).A number of circular magnetic anomalies occur in north-northwest and east-northeasttrending clusters in the southwest of the study area. These were interpreted to beintrusive plugs – possibly feeders for the dolerite sills and dykes that occur in the area.Radiometric data delineate geological units within the pre-Karoo basement. Granitic togranodioritic rocks (2.6 Ga) are enriched in uranium and thorium while tonalitic rocks arenot.Geological cross-sections, constructed along flight lines and tie-lines, suggest that thereare two or more sills at depth under the southwestern portion of the study area intrudedby the Venetia kimberlite pipes. In addition a large strongly magnetic anomaly with nosurface expression was identified in the northeastern area and modelled to be at about1200 m depth.

[发布机构] University of the Witwatersrand