An interpretation of the aeromagnetic data covering portion of the Damara orogenic belt, with special reference to the occurrence of uraniferous granite

Abstract

Abstract provided by author:

- Virtual geomagnetic poles were derived for the 500 Ma tectonothermal event and for the basement rocks in the area, the pole for the latter indicating an age of 2 150. Ma for these rocks

- A close correlation exists between positive magnetic anomalies and high radiometric responses over the red granites, reactivated basement and, to a lesser extent, over the Salem Granite Suite and other late- to post-tectonic granites. This could be a useful relationship, with the application of gamma spectrometry, as an aid to mapping

- A number of structural lineaments and broader lineament zones are, apart from the Okahandja lineament, identified and named for the first time, i. e. -the Uis lineament zone, - the Omaruru lineament, - the Welwitschia lineament zone, and the less prominent -Wlotzka and Abbabis lineament zones. Interactive computer modelling indicates that these geomagnetic lineament zones are in fact fault-controlled geanticlinal ridges bounded by relatively rapid monoclinal downfolding of the stratigraphy

- A post-F3 (northeast) structural phase, F4, oriented north-north-east is recognised as being a major structural event of particular significance to the emplacement of uraniferous granite

- The gravity studies indicate that the investigated dome structures result from an interplay between both vertical and lateral stress components. The former component arising from gravitational instability between rocks of the Damara Sequence and basement, and the latter component arising from the lateral stress fields prevailing at the time

- A number of structural lineaments and broader lineament zones are, apart from the Okahandja lineament, identified and named for the first time, i. e. - the Uis lineament zone, - the Omaruru lineament, - the Welwitschia lineament zone, and the less prominent -Wlotzka and Abbabis lineament zones. Interactive computer modelling indicates that these geomagnetic lineament zones are in fact fault-controlled geanticlinal ridges bounded by relatively rapid monoclinal downfolding of the stratigraphy