Tectonosedimentary expressions of the evolution of the Fungurume foreland basin in the Lufilian Arc, Neoproterozoic–Lower Palaeozoic, Central Africa

Abstract

AbstractThe Lufilian Arc is a part of the Neoproterozoic–Lower Palaeozoic Pan-African orogenic system within southern and central Africa. The succession of the Lufilian orogen, the Katanga Supergroup, contains large bodies of fragmental rocks recently interpreted as syntectonic conglomerates, which reveal the existence of two previously unrecognized basins and shed new light on tectonic evolution of the belt. Rifting between the Congo Craton in the north and the Kalahari Craton in the south at c. 880 Ma resulted in the opening of two rift basins: the Roan rift and the succeeding Nguba rift. During post-735 Ma orogenesis, north-advancing nappes supplied detritus into the Fungurume foreland basin in the northern part of the Lufilian Arc. The coarse-clastic sequence of the Fungurume Group includes olistostromes that contain olistoliths of the pre-existing Katangan rocks, rest upon a syntectonic unconformity and are overridden by the Katangan nappes/thrust sheets. Strong tectonic deformations of strata within the olistoliths reflect their provenance from the orogenic source of the Katangan nappes. By contrast, the olistostrome matrix is essentially intact even when olistostrome occurs as a part of a tight fold. These structural relations suggest that nappe overthrusting and further deformation of the foreland occurred soon after deposition of the olistostrome sediments, and prior to their lithification.