207-4 A magnetotelluric investigation of the Okavango Rift Zone, northern Botswana

Session: Honoring the Late Professor Mohamed Abdelsalam: Outstanding Researcher, Generous Colleague, Legendary Mentor, and Ambassador for the Geosciences In Africa

Presenting Author:

Estella Atekwana

Authors:

Matende, Kitso¹, Ranganai, R.², Evans, Rob³, Zhu, J.⁴, Laletsang, K.⁵, Mickus, Kevin⁶, Atekwana, Estella⁷, Brovko, Oleg⁸

Abstract:

The Okavango Rift Zone (ORZ) in northern Botswana is generally considered to be an incipient rift and the terminus of the southwestern branch of the East African Rift System (EARS). The ORZ offers a natural laboratory to understand rift development at early stages due to the absence of substantial tectonic and volcanic activity that could have overprinted pre-rift structures. Despite the numerous efforts directed towards unravelling the evolution and deformation in the ORZ, there is limited insight into how it is linked to the EARS, with several different studies providing conflicting evidence of the existence of rifting. In the current study, we used three-dimensional (3D) inversion modelling of magnetotelluric data to develop conductivity models from which we can interpret structures beneath the ORZ and surrounding areas. Our results show the ORZ to be underlain by a thick and resistive lithosphere, in conflict with models of magma assisted rifting. To the NW of the ORZ, our results reveal NE-SW oriented conductors located close to the margin of the Congo Craton and the Damara Belt that extend from the upper mantle to crustal depths. These conductors may be related to melts associated with the African super plume and, if that is the case, then they may play a key role in strain localization, and suggest that rifting is occurring further to the northwest than previously believed. An alternative explanation is that these conductors represent relict metasomatic signatures of past melting and deformation associated with past tectonic events.  

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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