The Geology, metamorphism and hydrothermal alteration of the Swakop Group on Daheim Farm in the Karibib District of Namibia

Abstract

Abstract provided by author:

Daheim Farm is made up of the Oberwasser, Daheim and Karibib Formations that form part of the Khomas Subgroup. The amphibolites of the Daheim Formation can be subdivided into various units on the basis of field appearance. These units often show characteristic mineralogies

The metamorphism of pelitic, mafic, calc-silicate and carbonate rocks has produced medium grade mineralogies characteristic of the amphibolite facies. Metamorphic temperatures and pressures experienced in the Daheim area have reached about 580°C and 3. 3Kb respectively, with the mole fraction Xco2 for the carbonate-rich rocks exceeding 0. 9. Metasomatism concurrent with metamorphism has affected the meta-pelite and meta-mafic rocks

The hydrothermal alteration of the Daheim rocks has occured in various stages. Pre-tectonic accumulations of metamorphically derived opaque oxides have been subjected to post-tectonic silification and potassic metasomatism with accompanying sulphide mineralization. Late stage carbonate and opaque oxide growth marks the end of mineral formation in the hydrothermal alteration zone