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Southeastern DR Congo and Zambia lie in a region of tectonic interest because of the presence of the embryonic southwestern branch of the East African Rift System (EARS). This branch is composed of unconnected basins extending for 1,700 km from Lake Tanganyika in the DR Congo and Zambia to the Okavango basin in Botswana. The opening of individual basins started during the Mesozoic Karoo rifting and continued in the Cainozoic and present rifting episode. Intensive seismic activity associated with northeasterly striking faults with a NW-SE extension is noticeable. From an elevation point of view, this region is a part of the central African Plateau at an average altitude of about 1200 m above the sea level. It displays the geophysical attributes of the EARS, i.e., a regional gravity low (-140 mGal amplitude) and anomalously high heat flow (ca 64 mWm-2) both associated with an upward of the lithosphere-asthenosphere boundary.
Anomalous Pn velocities are evidenced by a positive telesismic P wave delay time record (+0.5 s). To explain the origin of the elevated Kundelungu plateau, we applied thermoelastic modeling of lithospheric uplift by a finite difference numerical solution. The Kundelungu plateau is a large lithospheric block (around 750 km diameter) bounded by the extensional Congolese Upemba rift to the west and the Luangwa-Lukusashi Zambian basins to the east. Based on sedimentological data and geophysical modeling its present uplift is considered to have occurred since the Cainozoic. To obtain an uplift model, the physical properties of the lithosphere were estimated from the regional gravity field and surface heat flow data in order to obtain the exact timing and nature of the uplift. Using input values of initial lithospheric plate thickness, crustal thickness, and basal and radial heat fluxes, the elastic plate is deformed to provide estimates of elastic thickness, surface heat flow and elastic uplift. Preliminary estimates suggest that a heat flux of 100 mW/m-2 best over a 40 Million period best explains the observed uplift. Additional modeling using available tectonic and geophysical constraints may provide a possible mechanism of the Kundelungu uplift provided that the mechanism is thermoelastic uplift of the lithosphere due to basal and radial thermal anomalies.
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