The paper presents the results of mineralogical and chemical analyses of the clay fraction (<2 mu m) of samples from boreholes in the Etosha Pan and smaller pans of the Owambo-Pans-Plain in the Etosha National Park, northern Namibia. Four mineral associations can be differentiated within the vertical succession of the profiles in the Etosha Pan: I) analcime/K-feldspar and mica association; II) analcime/K-feldspar and sepiolite (loughlinite) association; III) expandable sheet silicate (saponite/stevensite) association; and IV) calcite and dolomite association. These mineral associations are the expression of the seasonal saline-alkaline to calciferous, saline-alkaline environment of the present Etosha Pan. The sedimentological and pedological descriptions, combined with the results of the mineralogical and chemical analyses, show a clear differentiation of the profiles of the Etosha Pan in: i) disintegrated sedimentary rocks of the Andoni Formation (mineral association I); ii) par-autochthonous sediments (mineral associations T and II); and iii) allochthonous sediments (mineral associations III and IV). Based on this vertical mineralogical differentiation, four sedimentological-mineralogical/ chemical zones are defined for the actual floor of the Etosha Pan. The zonation shows that a thin cover of allochthonous sediments is only present along the southern margin of the Etosha Pan, including Fisher's Pan. The results support the hypothesis that the Etosha Pan is an erosional form rather than a palaeolake. In principle, the zonal configuration of the recent allochthonous and parautochthonous sediments identified on the Etosha Pan provides a small-scale depositional environment model for the formation of the Etosha limestone and sediments of the Andoni Formation during the Oligocene and Miocene. Thus, the findings help to reconstruct the depositional environment of the evolution of the extensive depocentre of the Etosha basin during the Late Tertiary.
