Crustal domains in the northern Kaapvaal craton as defined by magnetic lineaments

Abstract

The northern part of the Kaapvaal craton and Limpopo belt can be subdivided into domains on the basis of aeromagnetic lineament patterns. These subdivisions reflect portions of the lithosphere with different tectonic histories and many of these domains correlate with known metamorphic-tectonic provinces. The dykes causing the lineation pattern intruded intermittently over a very long period of time, and, within a domain, the trend of the intruded dykes is determined not only by the stress field operative at the time of intrusion, but also by an inherited fracture pattern in that domain. The event that introduced the fracture pattern has to be older than 2456 ± 78 Ma and younger than 2603 ± 129 Ma. The magnetic lineation data show that a 15° anticlockwise rotation of the central zone of the Limpopo belt with respect to the southern marginal zone will restore parallelism in the fracture pattern of the two domains. The presence of the greenstone belts has no effect on the dyke pattern, and domain boundaries cut across these structures.