Response to the papers by Bailie et al. concerning the age and deposition of the Bushmanland Group (South African Journal of Geology, 110, 59–86) and single zircon ages of the Aggeneys Granite Suite (South African Journal of Geology, 110, 87–110)

摘要

We appreciate the comments by Colliston et al. (2008) on our recent publications concerning the age and deposition of the Bushmanland Group and the age of the Aggeneys Granite Suite (Bailie et al., 2007a; b). We welcome the debate around the geological significance of the analytical results but note that this can vary according to the stratigraphic/structural models that themselves evolve. We agree with Colliston et al. (2008) that the Namaqua mobile belt is highly structurally complex, being divided into a number of terranes bounded by major thrust faults and with complex stratigraphic relationships that require disciplined and detailed study. It has, nevertheless, being shown by previous authors (Rozendaal, 1975; Joubert, 1986; Ryan et al. 1986; Lipson, 1990; Laccasie et al., 2006) that despite the structural complexity of the area that various lithological units are consistent across large areas of Namaqualand, albeit that they have been duplicated by thrusting, faulting, shearing and other tectonic events.