Stratigraphic and structural setting of the Griqualand West and the Olifantshoek Sequences at Black Rock, Beeshoek and Rooinekke Mines, Griqualand West, South Africa

Abstract

The Black Rock to Rooinekke area has been influenced by the Kheis and Namaqua orogenies. Thrusting associated with the Kheis orogeny is well documented throughout the mining area. Thrusting at Rooinekke resulted in the Griqualand West Sequence rocks overlying parts of the Olifantshoek Sequence. At Black Rock lithologies of the Vo~lwater Subgroup have been thrusted onto the Olifantshoek Sequence. A prominent N-S trending graben structure has been observed in the Rooinekke, Beeshoek and Black Rock mining areas. The thrusts are disrupted by these N-S faults. At Rooinekke supergene replacement and enrichment of the iron ore is associated with pre-Olifantshoek N-S faulting. The Namaqua orogeny may also have played a part in upgrading the existing ore bodies under discussion.

Paleomagnetism of a lateritic paleoweathering horizon and overlying Paleoproterozoic red beds from South Africa: Implications for the Kaapvaal apparent polar wander path and a confirmation of atmospheric oxygen enrichment

“…Indeed, a prominent splay of the Blackridge thrust is exposed not more than 20–30 m above our sample sites at Rooinekke. This area has been substantially disrupted by late‐Namaqua faults [ Grobbelaar et al , 1995], and a hydrothermal origin has been demonstrated for manganese ore in the area [ Van Wyk , 1980]. We interpret the INT component as a low‐ to moderate‐temperature, hydrothermal CRM or pTVRM resulting from Namaqua orogenesis, akin to synorogenic hematitization within red beds in the Appalachian foreland [e.g., Lu et al , 1994].…”

“…The Griqualand West region is the foreland to E‐verging deformation related to the ∼1800–1700‐Ma Kheis and/or ∼1250–1000‐Ma Namaqua orogens [ Stowe , 1983; Onstott et al , 1986a; Altermann and Hälbich , 1991; Grobbelaar et al , 1995; Moen , 1999]. We sampled through a part of the foreland characterized by broad, open, shallow folds, interrupted by a single thrust fault (Blackridge thrust [ Beukes and Smit , 1987]) with local subordinate splays.…”

Seismic Stratigraphic Constraints on Neoarchean - Paleoproterozoic Evolution of the Western Margin of the Kaapvaal Craton, South Africa

“…KBF03A, where there is good outcrop control, were used to check the validity of assigned stratigraphic nomenclature to the seismic profile. For example, the published thickness of units from these well-studied areas (Stowe, 1986;Cornell, 1987Schlegel, 1988Altermann and Halbich, 1990;Altermann et al, 1992;Grobbelaar et al 1995;Moen, 1999) are compared to those along the seismic profiles, estimated using two way time (TWT) and P wave velocities given in Table 4. Along KBF03A, the Olifantshoek Supergroup comprises two units separated by an unconformity, here named the Neylan Unconformity (Nunc) (first recognised by H.S van Niekerk, RAU, personal communication 2000).…”

The carbonates of the Transvaal and Griqualand West sequences of the Kaapvaal craton, with special reference to the Lime Acres limestone deposit

“…Mineral deposits of Mississippi Valley Type (MVT) associated with the carbonates are described by Martini et al (1995). Mn and Fe mineralization of collapsed karst structures in the Ghaap Group dolomites led to some of the largest mineral deposits of iron and manganese in the world and are described by PlehweLeisen and Klemm (1995) Grobbelaar et al (1995), and Cornell and Schiitte (1995).…”