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The almost circular Roter Kamm impact crater, in 1200 Ma granitic gneiss of the Namaqua Metamorphic Complex of the southern Namib Desert, has a diameter of 2.5 km and an age of 4–5 Ma. A variable orientation of the foliation in the rim gneisses is suggestive of large-scale brecciation of the rim. Along some parts of the rim, the average orientation of the foliation in the rim gneisses is tangential, along other parts it is radial, and along still other parts it is random. New analyses of large samples of the rim gneisses demonstrate a large-scale chemical heterogeneity of the target rocks. Black cataclasite veins, although mineralogically identical to their host gneisses, are almost invariably more potassic than the latter. The ejecta apron outside the crater was deposited on the earliest, fossil-bearing, eolian sands of the Pliocene to Holocene Sossus Sand Formation. Subsequent calcretization cemented the apron, but erosion and redeposition of the ejecta have not been significant in the desert environment of the southern Namib. Younger Sossus Formation sands now fill the crater and partly cover the rim and the ejecta apron. Ejecta outside the crater are most abundant in an outward-fanning apron extending from the north-northwest to the west of the crater. Blocks between 20 cm and 1.5 m in size are concentrated in this main apron in concentrically and radially orientated swaths. The longest of the latter extends 5.5 km to the northwest of the crater. Sizes of fragments on the crater rim and mappable features in the rim that can be followed and fan out into the ejecta apron, together with a slight asymmetry of the crater, suggest that the trajectory of the impacting body was northwesterly.

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