Detrital white micas from molasse sediments of the Nama Group were dated by the K/Ar method. The Kuibis Subgroup and the underlying pre-Damara Sinclair Sequence contain detrital muscovite with ages of 1100-1000 Ma and thus cannot be derived from the Damara Orogen, but prove to have originated from a basement probably affected by the Kibaran orogeny. Muscovite size-fractions of 250-100 μm from the upper Nama Group (upper Schwarzrand and Fish River Subgroups) yielded K/Ar ages 670-570 Ma. Because these sediments are regarded as molasse series of the Damara Orogen, these K/Ar ages can be interpreted as cooling ages of a first, early tectono-thermal event in the Damara Orogen. A later Damaran metamorphic overprint, which peaked at about 530 Ma, is not documented in the detrital content of the Nama Group at the present level of erosion, because detrital micas with K/Ar ages over 600 Ma, have been found up to the uppermost Fish River Subgroup. It can be concluded that, at least, two tectono-metamorphic events followed by uplift and erosion, have taken place during the development of the Damara Orogen. Thermal alterations of the Nama sediments were detected by means of illite crystallinity and K/Ar dating of clay size-fractions. These data, as well as the almost exclusive occurrence of the 2M mica polytype in these size-fractions point to a diagenetic to very low grade metamorphic alteration of the area investigated at about 530-500 Ma and younger. The deposition of the upper Nama Group is younger than the 570 Ma detrital white micas but occurred before the 530-500 Ma thermal alteration of the Nama deposits. The deposition of the lower Nama Group probably took place between 635 and 570 Ma.