This is a poorly exposed complex an estimated 85% of which is obscured by sand and calcrete. It intrudes quartzites, schists and granites of Late Precambrian age and comprises a series of syenite intrusions that may form rings (Marsh, 1976, Fig. 5). The principal rock types are quartz monzonite, fine- and coarse-grained porphyritic syenites, biotite-rich syenite and leucocratic syenite, but none of these rocks contain alkali pyroxene or amphibole. The dyke rocks, however, which are not abundant, comprise feldsparphyric quartz bostonites, which contain arfvedsonite or aegirine-augite, and quartz-feldspar porphyry. Analyses for major and selected trace elements for the main rock types are given by Marsh (1976).