NEW GEOCHEMICAL AND PALAEOMAGNETIC RESULTS FROM NEOARCHAEAN DYKE SWARMS IN THE BADPLAAS-BARBERTON AREA, SOUTH AFRICA

A geochemical and paleomagnetic study was performed on southwest to northeast and northwest to southeast trending dyke swarms in the Badplaas-Barberton area, South Africa. The aims of the study were to contribute towards the debate on the tectonic setting and genesis of these calc-alkaline to tholeiitic dyke swarms. Thermomagnetic analysis indicated a very complex intrusion history with several episodes of magma influx and/or re-magnetization. Three poorly defined poles were identified and isolated from the northwest to southeast trending dykes. These poles correlate respectively with published poles for the ca. 2984 ± 2.6 Ma Agatha basalt from the upper Pongola Supergroup, the 2.71 to 2.66 Ga Allanridge Formation of the Ventersdorp Supergroup, as well as the 2050 ± 12 Ma Bushveld Complex. Overlapping geochemical signatures for the calc-alkaline northwest to southeast trending and more tholeiitic southwest to northeast trending dyke swarms prevent clear distinction between the proposed different intrusion events. However, geochemical similarities with previously published data from the Nsuze Group and upper Ventersdorp Supergroup, respectively, suggest tectonic settings ranging from intra-continental rift to back-arc settings.