1. GEOLOGY OF THE
KAYELEKERA URANIUM
DEPOSIT, MALAWI
A. Wilde, D. Princep, J.C. Corbin, E. Becker,
J. Mwenelupembe
2. Introduction & History
19,900t U3O8
At 0.08%
Cut-off 0.03%
AGIP 1977
— Airborne radiometric survey
— Secondary U near Kayelekera
CEGB 1983
— Recognised economic potential
— PFS concluded in 1986
— Licence lapsed in 1992
Paladin 1998
— Construction started in 2007
— First production in 2009
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19. Why is Kayalekera there?
Hybrid ore (9.2 & 9.4)
— 60% U stratiform & stratabound
— Lower grade
— 40% U structurally-controlled
— Higher grade
(At least) two ore events:
— Primary ore (Permian – Jurassic)
— East African Rift (Cretaceous –
today)
Driver/s for primary fluid flow?
— Topographic (rifting)
— ± Convection (rifting)
— Jurassic volcanism?
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20. Why is Kayalekera there?
Primary ore deposition
— In situ vs mobile reductant?
— No relationship to channels
Secondary ore deposition
— Fault control
Uranium source?
— Is it important?
— Basement geology poorly
understood
— Uraniferous pegmatite
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21. Implications for Exploration
MORE RESEARCH IS NEEDED!
Ore geochronology
Local provenance studies
Ore mineralogy & paragenesis
Distribution and characteristics of
clay minerals
Collaborative Research Initiative?
John Mwenelupembe, project manager
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Editor's Notes
The East African Rift is an active continental rift zone in eastern Africa that appears to be a developing divergent tectonic plate boundary. In the past it was considered to be part of a larger Great Rift Valley that extended north to Turkey. The rift is a narrow zone in which the African Plate is in the process of splitting into two new tectonic plates called the Somali Plate and the Nubian Plate, which are subplates or protoplates.The East African Rift consists of two main branches called the Gregory Rift and the Western Rift Valley. These result from the actions of numerous normal (dip-slip) faults which are typical of all tectonic rift zones. The Eastern Rift Valley includes the Main Ethiopian Rift, running eastward from the Afar Triple Junction, which continues south as the Kenyan Rift Valley. The Western Rift Valley includes the Albertine Rift, and further south the valley of Lake Malawi.The Great Rift Valley of East Africa—the birthplace of the human species—may have taken much longer to develop than previously believed, according to a new study published this week in Nature Geoscience that was led by scientists from James Cook University and Ohio University.The team's findings suggest that a major tectonic event occurred in East Africa as far back as 25-30 million years ago, rearranging the flow of large rivers such as the Congo and the Nile to create the unique landscapes and climates that mark Africa today."The findings have important implications for understanding climate change models, faunal evolution and the development of Africa's unique landscape," said lead author and geologist Eric Roberts of the James Cook University in Australia. 2012Roberts, E.M., Stevens, N.J., O’Connor, P.M., Dirks, P.H.G.M., Gottfreid, M.D., Clyde, W.C., Armstrong, R.A., Kemp, A.I.S., and Hemming, S. Initiation of the western branch of the East African Rift coeval with the eastern Branch. Nature Geoscience 5. DOI: 10.1038/NGEO1432.
