Abstract
M.Sc. (Geology)
The Mozaan Group of the Pongola Supergroup together with the correlative Witwatersrand
Supergroup host the oldest, best-preserved cover successions deposited on a stable craton
between 2.96 – 2.84 Ga ago. Little is known about the tectonic processes which operated on
the young Earth in the Archean. Paleomagnetism remains the most robust method with which
early cratonic movements can be constrained. There is a poor paleomagnetic record for the
Kaapvaaal Craton during the Archean. This study aims to contribute to the pole density and
constrain the apparent polar wander path (APWP) for the Kaapvaal Craton during this period,
as well as to interrogate the sediment source of the Klipwal Member diamictite. The
provenance of Klipwal diamictite was previously poorly understood. This study contributes
new insight as to the origin of the sediments making up this unit. The geochemical data
suggests a strong mafic to ultramafic source with minor felsic input. The CIA is consistent
with moderate weathering which probably took place at the source. The elevated levels of
iron are attributed to the precipitation of ferric-oxyhydroxides from the anoxic seawater with
a high concentration of dissolved iron. Petrographic and field studies suggest that sediments
were sourced from an off craton greenstone terrane adjacent to the Witwatersrand – Mozaan
basin indicating that the extent of glaciation was more extensive than previously thought. A
glacial influence is envisioned but more reliable data is required. During thermal
demagnetisation, a low temperature (250 - 350°C), steep northerly negatively inclined
component HIG was observed. Because of the negative bootstrap fold test, this component
has been interpreted to be an overprint. A total of six sites were sampled but only five
produced meaningful results. Sites KWU, KWV, KWW, KWX and KWZ show no preferred
grouping which impedes the calculation of a reliable pole. Individual VGPs were calculated
for these sites to reveal three groups when plotted together with Meso – Neoarchean poles.
Sites KWX, KWZ and other previously proposed poles for the Klipwal diamictite record an
overprint around 2.8 - 2.7 Ga This overprint is associated with post-Pongola granites which
intruded the Pongola Supergroup during this interval. Another group is observed around 1.05
Ga as recorded by sites KWU and KWV. This event is interpreted as an overprint associated
with the Namaqua-Natal orogeny which affected the eastern margin of the Kaapvaal Craton
during this time. All the sites were ultimately combined to calculate an average pole situated
at longitude = -40.3° and latitude 69.1° with α95 = 12 presented in this study. This new pole
together with those previously proposed demonstrates that a reliable APWP for the Kaapvaal
Craton during the Archean remains elusive.