Hermann E. Praekelt

A progressive ductile shear model for the Proterozoic Aggeneys Terrane, Namaqua mobile belt, South Africa

Abstract Recent structural and stratigraphic study results indicate that the Namaqua orogenesis (ca. 1.2 Ga) involved relative movement of lozenge shaped suspect terranes. Detailed study of one of the terranes, the Aggeneys Terrane, provided important information concerning the deformation process. The principal process was differential shear which produced complex structures such as interference folds and thrust faults. All the observed deformational structures can be explained by a single long-lived compressional event.

The stratigraphic interpretation of a highly deformed Proterozoic region in Central Bushmanland, South Africa: first correlation of structurally separated metasediments of the Aggeneys Subgroup

Abstract It is demonstrated that highly deformed and structurally separated Proterozoic metasediments, which have previously defied stratigraphic and sedimentological classification, may be correlated and characterised. This is done by using a multidisciplinary approach, including stratigraphic and structural mapping and sedimentological interpretation, developed during the Geodynamics Programme in Western Namaqualand (1975–1980). The metasediments under consideration belong to the economically important Aggeneys Subgroup, which hosts stratabound massive sulphide deposits at Aggeneys and Gamsberg (Gams). Four isolated areas are considered and it is shown that the Dabenoris, Kabas and Pella Formations, and the lower part of the Achab Formation are equivalent to the lower part of the Wortel Formation, and that the upper part of the stratigraphic column is composed of the upper units of the Achab Formation, the Gams Formation and the Blomhoek Formation. The Zuurwater Formation is, for the most part, equivalent to the lower portion of the Wortel Formation, but the uppermost strata are correlated with the Blomhoek Formation. These results illustrate that it is possible to obtain the information necessary for a palaeobasin analysis from even the most complex Proterozoic regions.