The combined extent of the Kalahari Craton in southern Africa and Grunehogna Craton Dronning Maud Land, Antarctica (DML), defined by surface exposures is well established and comprises ca 1518300 km2. Two small exposures recently recognised at Brekkerista, Sverdrupfjella with an age of ca. 2850 Ma confirm Archaean crust underlying the Maud Belt. Archaean crust underlying the Maud Belt was previously inferred from xenocrysts and NdTDM data from Cambrian to Neoproterozoic granites and Mesoproterozoic gneisses in western DML. Neoproterozoic-Cambrian granites with highly evolved Nd characteristics have been reported as far east as the Conrad Mountains, CDML suggesting that much of western CDML is similarly underlain by Archaean crust at depth. Similarly Cambrian minettes at Schirmacher oasis have NdTdm ages >2.0 by. In central Mozambique, Mesoproterozoic gneisses underlying the Barue Complex along the E margin of the Kalahari Craton, similarly have NdTdm signatures indicating probable Archean basement at depth. In the Nampula Complex Neoproterozoic to Cambrian age granites, east of the Namama Shearzone have relatively juvenile characteristics whereas those west of the shearzone have evolved characteristics. On reconstruction of Gondwana, these data suggest that the Archaean crust extends at depth at least up to the Orvinfjella Shearzone and east of Schirmacher Oasis in CDML and up to the Namama Shearzone in northern Mozambique. The extent of the revised distribution of exposed and subcrustal Archaean crust in southern Africa and Antarctica suggests an area of 1731000 km2, an increase in area of 14%. The recognition of extensive Archaean crust underlying DML, particularly that underlying the Maud Belt and CDML, provides insight to the nature of thickened crust indicated by aero-gravity, satellite gravity and seismic tomography data (Grantham et al., 2019). The thick crust in this area has been interpreted as resulting from the Kuunga Orogeny, a Neoproterozoic-Cambrian continent-continent collision between N and S Gondwana from ca. 570 Ma to ca. 480 Ma (Grantham et al., 2013, 2008). Crustal thickness estimates suggest that the thickened crust extends at least to the Gamburtsev Mountains, underlying much of East Antarctica.

Reference(s)

Grantham, G.H., Kramers, J.D., Eglington, B., Burger, E.P., 2019. Precambrian Research 333. https://doi.org/10.1016/j.precamres.2019.105444

Grantham, G.H., Macey, P.H., Horie, K., Kawakami, T., Ishikawa, M., Satish-Kumar, M., Tsuchiya, N., Graser, P., Azevedo, S., 2013. Precambrian Research 234, 85–135. https://doi.org/10.1016/j.precamres.2012.11.012

Grantham, G.H., Macey, P.H., Ingram, B. A, Roberts, M.P., Armstrong, R.A, Hokada, T., Shiraishi, K., Jackson, C., Bisnath, A., Manhica, V., 2008. Geological Society, London, Special Publications 308, 91–119. https://doi.org/10.1144/SP308.4.