A Dissertation Submitted to the Faculty of Science
University of the Witwatersrand, Johannesburg
for the Degree of Master of Science. / Beatrix Mine is located 35 km south of the city of Welkom in
the Welkom Goldfield and as such forms the most southerly of
the Witwatersrand-type gold mines.
The Beatrix Reef overlies an angular unconformity at the
base of the Turffontein Subgroup, Central Rand Group
Significant, southerly truncation of over 600m of the
Johannesburg Subgroup, and the lower formations of the
Turffontein Subgroup, occur at this unconformity in the
Beatrix area..
characteristics of the Beatrix Reef conglomerates such as
the morphology, sorting and packing of clasts, and the
arrangement. of the sediments in various sedimentary
structures and facies/ sequences, suggest deposition within a
braided fluvial environment on a coarse-grained braid-delta.
Sedimentation occurred after the fluvial degradation of
previously deposited units, and culminated in a marine/
lacustrine transgression. Low aggradation rates led to
significant reworking and concentration of placer materials
in a depositional model probably typical of ventral Rand
Group placer formation. Heavy minerals (and gold) are
concentrated in response to hydraulic conditions and show a
close association with large and small scale sedimentary
features. Transport directions deduced from the sedimentary
structures suggest a north to south dispersal of sediment
down the braid plain.
Sedimentary structures in the finer rained units at the
base of the Eldorado Formation are indicative of tidal
influences and document the marine transgression as the
culmination of the degradational events.
The lithologys sedimentary structures and facies sequences
of the coarser grained units of the Eldorado Formation
well as the overall coarsening upward of these lithologies
indicate sedimentation in a braided , fluvial system, on an
alluvial fan prograding across the preyiously deposited
units" Sedimentary ~tructures and lithologic variations
confirm a continued north to south dispersal pattern.
In the area south of the Sand over the period of fluvial
degradation and transgression after the formation of the
Beatrix: Reef was followed by more rapidly aggreding fluvial
progradation due to a major change in base level in response
to compressional tectonics and uplift along the Western
Margin Structure. Only in post-Central Rand Group times did
relaxation and extensional tectonics result in the
outpourings of the Ventersdorp .supergroup lavas and the
cessation of active Witwatersrand Supergroup sedimentation. / Andrew Chakane 2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/25042 |
| Date | January 1990 |
| Creators | Genis, Jac H |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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