Lithospheric Thickness, Rift and Inversion Tectonics: The Formation and
Deformation of the Neoproterozoic Katangan Basin of Central Africa.
Abstract
The tectono-stratigraphic development of continental basins is key to
our understanding of the location and scale of metal deposits required
by the energy transition. We examine the Neo-proterozoic Katangan copper
basin of Central Africa to determine the link between lithosphere and
crust and the generation of potential fluid pathways. Integration of
lithospheric thickness, quantitative basin analysis and structure,
defines a basin scale tectono-stratigraphic model for controls on
potential fluid pathways. The basin developed along the thinned (140-170
km thick) margins of the Congo, Kalahari and Bangweulu cratons. Crustal
scale fault zones define these margins and imply a mechanical weakness
in the basin. Drill core and seismic data show extensional, half graben
geometries. Basin subsidence analysis indicates two phases of
rift-driven subsidence and increasing lithospheric extension from the
basin boundary to a Central Rift Zone (CRZ). The CRZ also maps out as a
sediment provenance boundary. Subsequent Late Ediacaran and Cambrian
orogenesis and rift-fault inversion occurred most intensively within the
CRZ. Basin expulsion and thrust tectonics resulted in a narrow belt of
crustal thickening defined today by a ~50 km wide zone
of garnet amphibolite facies metamorphism. The spatial coincidence of
early crustal extension, relatively thin lithosphere, and later intense
basin inversion along the CRZ, indicates that pre-existing crustal
structure and weakness was a key tectonic control. The reactivated
structures define several tectonic domains, control basin architecture
within the zones and occur as potential fluid pathways for high volume
fluid migration for metal bearing brines.