Zambezi: a new palaeodrainage evolution.

07/05/2020

A new, more complete Zambezi paleodrainage evolution is presented, based on timing of Karoo rift reactivations and subsequent stream capture events (see also Bonne & Caracciolo 2017). 

Our alternative Zambezi River evolution is based on high-resolution geomorphology constraints and the evolution of regional and local stress fields. The river evolution is controlled by the propagation of rifting and graben formation of the East African Rift System, into southern Africa, forking into the continent as the southwestern branch of the East African Rift System, ending in the Okavango rift. 

Well-constrained timings of rift initiation and using the knowledge of drainage development upon incipient rift systems and associated structures, the Late Cenozoic palaeodrainage evolution of the Zambezi River is found to differ from the publically accepted (and undisputed) evolution. This is due to different timings of reactivation and the subsequent changes in erosional base level, needed for a trunk stream to be able to capture hinterland drainage

Based on the combined analysis of fluvial and tectonic landforms, the linkage of the Upper and Lower Zambezi, forming the Victoria Falls, is believed to have occurred at a different time. 

Basement units of Mozambique
Basement units of Mozambique

Some study outcomes Zambezi palaeodrainage:

  1. The modern, large Zambezi is a recent phenomenon, but also the older, shorter Zambezi had at some moments in time a significantly high solid sediment flux, in turn having a considerable impact on sedimentation in the Zambezi Depression.
  2. Capture mechanisms of the Zambezi River, and changing sandstone compositions.
  3. Changes in the exact location of the outlet of the Zambezi River, dictated by fault activity.

  4. Interactions of the downstream Zambezi River with the Pungoé and Buzi rivers.

  5. Changes in offshore sandstone mineralogy, reflecting hinterland uplifts, river captures, active erosion in sub-basins with varying outcrop lithologies, gradual erosion of Karoo LIP basalts, exposure at rift shoulders of various Precambrian metasedimentary, metamorphic and magmatic basement suites, erosion of Karoo, Cretaceous and EARS rift sediments. 

Go back to Highlights, or check what we have on the Rovuma and Limpopo rivers.

Zambezi overview, basin, streams, Phanerozoic, Neogene.
Zambezi overview, basin, streams, Phanerozoic, Neogene.
Rift shoulder, East Africa.
Rift shoulder, East Africa.
¬© 2013-2022 Kathelijne Bonne. Copyright notice: All information on this website is the intellectual property of Kathelijne Bonne and none of it may be copied, reproduced, used, distributed or otherwise handled without prior written agreement. All information given is approximate and may have been altered for confidentiality purposes. K. Bonne reserves the right to make changes without prior notice. The displayed information has an informative purpose only, no exact data or results are given. Photograph credit: All images and pictures are either from K. Bonne or from the public domain unless otherwise stated. If an image lacks proper credit please get in touch so we can solve the issue. 
Powered by Webnode
Create your website for free!