The geology, geochemistry and metallogeny of the felsic rocks of the bushveld complex, North of Bronkhorstspruit, South Africa
Date
2016-06-08
Authors
Bailie, Russell Hope
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Abstract
The felsic rocks ofthe Bushveld Complex are host to abundant, small polymetallic
mineralisation. The study involved mapping and metallogenic characterisation of an area
north of Bronkhoratspruit, in the acid phase of the Bushveld Complex.
The upper Rooiberg Group shows an evolution from rhyodacites of the Kwaggasnek
Formation to rhyolites of the Schrikkloof'Formarion. The Rooiberg Group formed from the
same magma that formed the underlying granophyres. The granites represent further
fractionation of the same parental magma, evolving from grey hornblende-rich granites at
the base of the sheet to red biotite-rich granites at the top.
Mineralisation is derived from highly fractionated granites that evolved to water saturation.
Structural controls also influenced hydrothermal fluid flow. The mineralisation progresses
from a magmatic Sn assemblage through a Cu-Pb-Zn assemblage to a late meteoric Fe-U-F
assemblage superimposed on earlier assemblages. Progressive fluid mixing from magmatic
to meteoric characterised the development of the paragenetic sequence.
Description
A dissertation submitted to the Faculty of Science, University (If the
Witwatersrand, Johannesburg, in fulfilment of the requirements for the
degree of Master of Science.
Johannesburg, 1997