Magnetic modelling of the Umvimeela and East Dykes: evidence for regional tilting of the Zimbabwe Craton adjacent to the Limpopo Belt

Models of the Umvimeela and East dykes of Zimbabwe have been deduced from aeromagnetic data. Assuming a constant magnetic susceptibility and direction of remanent magnetization the models show the two dykes are essentially vertical with a mean dip of 84 towards the Great Dyke for the Umvimeela dyke and 89° away from the Great Dyke for the East dyke (excluding results from south of latitude 20.5 S). There is a large variation in the width of the dykes. A mean width of 204 m for the Umvimeela dyke and 106 m for the East dyke were obtained. The large errors may represent true variations in width or result from variations in the susceptibility. Both dykes have shallower dips south of latitude 20.5 S. The Umvimeela dyke has a mean dip of 70 and the East dyke of 80°. This, together with palaeomagnetic data from the Umvimeela dyke, suggests a tilting of the Zimbabwe craton adjacent to the Limpopo Belt over a zone about 100 km in width. The axis of rotation is roughly parallel to the northern margin of the Limpopo Belt.

An environmental analysis of the Umvimeela and East Dykes of Zimbabwe.