Batoka Basalt Fm
Type Locality and Naming
Mid-Zambezi Basin. Named after the spectacular Batoka Gorge, which was carved by the Zambezi River immediately downstream of the Victoria Falls on the border between Zambia and Zimbabwe. The falls and the gorge are entirely hosted within these basalts.
Synonym: Batoka Formation
Lithology and Thickness
A massive succession of subaerial, tholeiitic continental flood basalts. The total preserved thickness varies but exceeds 400 to 1,000 meters in the deeper parts of the basins. It comprises stacked individual lava flows that range from a few meters to over 30 meters thick. The centers of the flows are massive, hard, and jointed (forming the vertical cliffs at Victoria Falls), while the tops and bottoms of the flows are highly vesicular (filled with amygdales of quartz, chalcedony, and zeolite minerals).
Relationships and Distribution
Lower contact
Conformably to paraconformably overlies the massive, aeolian desert sandstones of the Forest Sandstone Fm (Zimbabwe) or the Ntane / Bodibeng Sandstone Fm (Botswana).
Upper contact
Unconformably overlain by the much younger, unconsolidated sediments of the Cenozoic Kalahari Gr, or forms the modern erosional surface (as seen extensively around Livingstone and Victoria Falls).
Regional extent
Widespread across northwestern Zimbabwe, southern Zambia, and northern Botswana. Karoo Volcanics; Stormberg Lavas. It is the direct regional chronostratigraphic equivalent of the Drakensberg Gr (South Africa/Lesotho), Stormberg Lava Gr (Kalahari Basin) and the Kasane/Kwitane Basalts (Botswana).
GeoJSON
Fossils
Age
Depositional setting
Continental flood basalts (Large Igneous Province).
Additional Information
The Batoka Basalts are geomorphologically famous for hosting Mosi-oa-Tunya (Victoria Falls). The falls continuously migrate upstream by exploiting the east-west trending tectonic fracture zones and softer, vesicular flow-tops within the basalt succession.