The age of the Koegel Fontein anorogenic complex, South Africa, and its relationship to the regional timing of magmatism and breakup along the South Atlantic rifted margin

Abstract

The early Cretaceous Koegel Fontein intrusive complex is situated near the Atlantic coast in South Africa, about 350 km northwest of Cape Town. The complex comprises felsic units of granite and syenite with compositionally related dykes, and a single intrusive plug of diorite. Existing zircon U-Pb ages of 144 ± 2 Ma for the syenite and 133.9 ± 1.3 Ma for the granite suggest that the emplacement of the complex took place over a period of about 10 My. This study provides additional and independent ages of the Koegel Fontein complex by 40Ar/39Ar dating to confirm the onset and duration of magmatism and better define the sequence of igneous units that comprise it. Show more