The Waterberg project, Limpopo province, South Africa
Date
2018
Authors
Huthmann, Florian Marius
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Abstract
The Waterberg deposit is located north of the Northern Lobe of the Bushveld Complex in South
Africa and represents a large, high-grade, new platinum-group element (PGE) discovery. The
northeast-oriented lobate arc of ma c to ultrama c rocks extends 24 km from the previously known
outcrop of Bushveld rocks. Laser ablation ICP-MS zircon U/Pb geochronology has returned ages
of 2059 ± 3 and 2053 ± 5 Ma for the intrusion, ages that are within error of previously published
ages for the Bushveld Complex of 2.056 Ga. It is therefore proven that the Bushveld Complex
extends further to the north than previously thought. Based on laser ablation ICP-MS zircon U/Pb
geochronology, detrital zircons extracted from the sedimentary rocks unconformably overlying the
succession have a maximum depositional age of 2045 Ma and abundant peaks of Archean age. It
may be argued that the Bushveld Complex now reaching to the Palala Shear Zone to the north
indicates that assembly of the Kaapvaal and Zimbabwe Cratons only took place around 2.0 Ga.
In detail, theWaterberg succession consists of a basal Ultrama c Sequence of harzburgite and feldspathic
pyroxenite, overlain by the Troctolite-Gabbronorite-Anorthosite Sequence and locally Upper
Zone, comprising magnetite gabbronorite and gabbro. Logging and geochemical data demonstrate
that all samples represent ultrama c to gabbroic cumulate rocks dominated by varying proportions
of olivine, plagioclase, clinopyroxene, and orthopyroxene. Mineralization occurs in the T
and F Zones located just below the Upper Zone and in the Ultrama c Sequence, respectively.
The Waterberg Project is an outstanding discovery with an indicated mineral resource of 25 Moz
Pt+Pd+Rh+Au.
Detailed geochemistry for the the lower mineralized F-Zone of the deposit indicates that although
the Northern Lobe and the Waterberg Project share many geochemical features, there are also
signi cant di erences. Sr isotopic data for plagioclase of the succession are di erent from values
reported for the Northern Lobe of the Bushveld Complex. Together with geochemical data, the
isotopic analyses suggest that a separate magmatic basin exists in the far northern Bushveld
Complex. That is, although both intrusions are roughly coeval, the Waterberg succession was at
least partially separated from the Northern Lobe and evolved independently.
In summary, the Waterberg Project represents a highly mineralized Bushveld Complex-age succession
sharing geological characteristics with the Northern Lobe. There are also clear di erences,
however, and the two areas cannot be directly linked. Therefore, the project area is interpreted to
represent a separate magmatic basin from the Northern Lobe, that is likely to include the rocks
at the very northern end of the Northern Lobe of the Bushveld Complex. The results of this work
have been published in four scienti c articles and presented at four academic conferences.
Description
A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfillment of
the requirements for the degree of
Doctor of Philosophy
School of Geosciences, University of the Witwatersrand, 2018