Abstract

The late Precambrian Nama beds of the Naukluft Mountains in South West Africa show intense Alpine-type deformation.

The crystalline basement underlying these rocks is little disturbed. Its upper surface is basin-shaped. The intensity of deformation in the overlying Nama beds increases upward to a practically undedormed unconformity which separates the Nama into two folded units. The unconformity is overlain by a strikingly uniform and little disturbed dolomite bed. Above this dolomite the intensity of deformation once more increases; it reaches its maximum in this upper deformed unit. The folds delineate a cascading movement from the topographically higher northern hinterland and form a great arc in front of the steepest slope of the basin, overriding the undeformed Nama beds of the southern foreland in a number of thrust sheets and nappes.

These observations, based on detailed mapping from exceptionally favorable exposures, bring out a movement pattern which is plainly controlled by the shape of the basin. Such a pattern is best interpreted as due to plastic flow under the influence of gravity.

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