The archean granites of mumias– kakamega-kisumu region of western kenya: petrography, petrogenesis and economic potential.
Abstract
Western Kenyan greenstone belt which extends into Tanzanian is highly composed
of Archean granites. The study area is concerned with the occurrence of the Kisian,
Maragoli and the Mumias granites. These are generally referred to the KisumuKakamega-Mumias
Archean granites. These three granite formations are closely
related to each other both microscopically and megascopically.
Their geochemistry confirms that they are closely related. Their geology can also
be related to the geology of the Tanzanian Craton given the similarities in their
elemental composition.
The Archean Maragoli granites and the Archean Mumias granites have been dated
at 2504±48 Ma (Rb:Sr, Dodson et al.,1975) and at 2495±70 to 2577±100 Ma
(K:Ar, Cahen and Snelling, 1966) respectively. According to Bell and Dodson
(1981), the initial 87Sr/86Sr ratios derived from whole rock Rb-Sr isochrones and
errorchrons are generally low indicating that the granitic magmas formed by partial
melting of protoliths with short prior residence time in the crust thus the granitic
crust underlying Tanzania and parts of Uganda and Kenya (with reference to
western granites) formed about 2.8 Ga and 2.4 Ga.
Huddlestone et al. (1959), states that the Archean Maragoli granites in the south
and the Archean Mumias granites in the north are intrusive into the rocks of the
Nyanzian and Kavirondian systems. There is little however to distinguish them
either in hand specimens or in thin sections and it is possible that they are part of
one large batholiths.
Granites have widely been used globally for different purposes. These include the
building and construction industries. Such areas include the building of roads,
dams, bridges and houses.
My sincere gratitude goes to my project advisor Dr. D. Ichang’i for the support and
guidance he offered to me throug
Citation
Bachelor of Science Degree in GeologyPublisher
University of Nairobi Geology