The geology of an area southeast of the Brandberg, South West Africa

Abstract

Abstract taken from Opsomings, Bloemfontein, 1971, p. 100 [corresponds with abstract from original thesis] :

Extreme conditions of metamorphism resulted in the fusion of the sediments in the deep-seated roots of synclines. The granitic magna which was thus produced, intruded at different stages as three different types of granite. Conditions of the bornblende-hornfels facies of contact metamorphism were caused by the intrusions

The only other rock in the area are dykes of dolerite which probably belong to the Karoo System. Superficial sediments, Tertiary in age, cover the larger part of the area

The sediments of the Damara System are believed to have been deposited as sandstone, greywacke, shale and limestone in a slowly sinking geosyncline. Compressive stress from the south-east, caused the isoclinal folding of these sediments. Later stress, directed from the north-east, gave rise to dome-like structures in the schist. Some of these structures were intruded by diapiric-like intrusions of granite. A conspicuous normal fault, with a north-easterly strike, cuts through the domes. This proves that it post-dates the last period of folding

A few pegmatites have been worked in the area. but seem to have been of little economic importance