TECTONOMETAMORPHIC PATTERNS DEVELOPED DURING PAN-AFRICAN CONTINENTAL COLLISION IN THE DAMARA INLAND BELT, NAMIBIA

The Pan-African Damara orogenic inland belt (Namibia) allows to invest igate the tectonometamorphic evolution along and across strike of an a ncient active continental margin. The supposed southernmost edge of th e overriding plate (Congo Craton), the Okahandja Lineament, separates a high-temperature/low-pressure (Central Zone) from a medium-temperatu re/medium-pressure metamorphic belt (Khomas Trough), both of which exp erienced different styles of sedimentation, deformation, metamorphism and magmatism through their geological history of continental separati on and continental collision. The present study summarizes patterns of structural evolution, metamorphism and geochronology from both terran es. Structural and metamorphic signatures are well correlatable along tectonic strike of the respective terranes. In spite of obvious differ ences in the geological evolution of both terranes, the Okahandja Line ament does not represent a sharp break in tectonometamorphic patterns. Although a proper high-temperature metamorphic belt, interpreted as c ontinental magmatic arc with abundant intrusions, is developed in the Central Zone, the metamorphic grade continuously decreases across the lineament towards the accretionary complex of the Southern Zone, and g eochronological data suggest a comparable metamorphic history in both terranes. We conclude that the majority of structural and metamorphic features in both terranes is associated with the late tectonic metamor phism resulting from crustal thickening and subsequent thermal relaxat ion, and that the actual late- to post-metamorphic juxtaposition of di fferent crustal levels in restricted to localized zones off the ancien t continental margin of the Okahandja Lineament.