Page 21 - Leshobo Technical Report_October2016

Technical Report for the

LESHOBO LIMESTONE

Taung, North-West Province

4.1.2. The Campbellrand Subgroup

The Ghaap Plateau facies consists of 8 formations which include, Monteville, Reivilo,
Fairfield, Klipfonteinheuwels, Papkuil, Klippan, Kogelbeen and Gamohaan Formations (Fig
3.3). The Prieska facies consist of two formations which include, Nauga and Naragas
Formations (Harding, 2004). The Campbellrand Subgroup forms the Campbellrand
escarpment and Ghaap Plateau in Griqualand West. It conformably overlies shale of
the Schmidtsdrift Subgroup, which forms the base of the Transvaal Supergroup in
Griqualand West, and is in turn conformably overlain by the Kuruman iron formation. Its
sequence is virtually undeformed, dipping gently at 1-20 to the west on the Ghaap
Plateau. A set of north-westerly striking faults displaces the sequence. South of Prieska
the sequence is faulted out against the Doringberg shear zone (Coward and Potgieter,
1983).

The Ghaap Plateau facies consists of giant stromatolitic dolomite domes, columnar
stromatolitic dolomite, stratified stromatolitic dolomite, domal and chertified dolomite,
sparry dolomite, net-like fenestrae dolomite, oolitic dolomite and limestone, dolomite
and chert in shale breccias, quartz arenites, dolarenites and argillites, cherts and tuffs.
The depositional environment of the Campbellrand Subgroup was interpreted to have
been a stable shallow marine platform and basin, provided by the Kaapvaal Craton
(Beukes, 1980, 1983).

The underlying Vryburg Formation lavas of the Schmidtsdrif Subgroup has an age of
2642 ± 3 Ma (Walraven and Martini, 1995). The overlying Gamohaan Formation has a
U-Pb zircon age of 2521 ±3 Ma and 2516 ±4 Ma. The underlying Monteville Formation
has U-Pb zircon ages of 2555 ±19 Ma. Dates of about 2465±7 Ma from the base of
the overlying Danielskuil Formation (Asbestos Hills Subgroup) have been obtained
(Trendall et al., 1995; Sumner and Bowring, 1996; Altermann and Nelson, 1998; Nelson
et al., 1999). Thus, the deposition of the Campbellrand took place between 2600-2500
Ma.

4.1.3. The Monteville Formation

The Monteville Formation represents the lowermost unit of the Campbellrand Subgroup
in the Ghaap plateau region. It overlies the Clearwater Formation of the Schmidtsdrif
Subgroup and overlain by the Reivilo Formation ( Beukes, 1980; Beukes, 1978;
Altermann and Siegfried, 1997). The underlying Vryburg Formation (Schmidtsdrif
Subgroup) lavas have an age of 2642 ± 3 Ma (Walraven and Martini, 1995). The
overlying Monteville Formation has U-Pb zircon ages of 2555 ±19 Ma.

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