Granites and their mineralisation in the Swakop River area around Goanikontes, Namibia

The Goanikontes area is situated along the Swakop River, west of the confluence with the Khan River and approximately 35 km inland from the town of Swakopmund (Fig. 1). The area lies within the Central Zone of the northwest-trending branch of the Damara Orogen which is characterised by a large number of igneous bodies that are dominantly granitic (Miller, 1983). Sheeted granitoid intrusions are extremely well exposed in the Khan and Swakop Rivers. These leucogranite sheets, locally termed alaskites, are mineralogically and texturally variable and are emplaced into both basement rocks and younger Etusis, Khan, Rossing and Chuos Formations of the Damaran cover sequence. Different types of alaskite sheets can be distinguished in the field although there is probably a continuum be tween some of these alaskite types. Late-stage sheeted granite intrusions are locally of economic interest on account of the associated uranium mineralisation. The Rossing Mine has produced uranium since the late 1970s and an uranium anomaly in the Goanikontes area has been investigated for its economic potential although it has never been developed. Detailed fieldwork has been carried out in the area of the Goanikontes uranium anomaly to make comparisons and contrasts with the Rossing deposit as part of a project to understand controls on mineralisation. The work in this paper is a preliminary report based largely on fieldwork.