New U–Pb SHRIMP zircon age for the Schurwedraai alkali granite: Implications for pre-impact development of the Vredefort Dome and extent of Bushveld magmatism, South Africa

Geochemistry and petrogenesis of tholeiitic intrusions of possible Bushveld-age in the Vredefort Dome, South Africa

“…It is thus possible that the results of Coetzee and Kruger (1989) give a to young age for the Losberg intrusion. Recently, Buick et al, 2001) constrained the emplacement of the Rustenburg Layered Suite of the Bushveld Complex to approximately 2.059-2.061 Ga, and Graham et al (2005) reported an age for the Schurwedraai alkali granite of 2.052 Ga. Since this granite cuts the Parsons Rust dolerite-norite and the Reebokkop dolerite the conclusion is that the tholeiitic group is older than 2.052 Ga, and the possibilty of the tholeiitc group having an age similar to the Rustenburg Layered Suite increases.…”

“…1). The collar rocks of the roughly circular dome are Precambrian rocks of the Dominion Group, and Witwatersrand Supergroup, as well as a large volume (%30%) of plutonic and hypabyssal rocks that have formed over a long geological time span that include the formation of the epidiorites of the Klipriviersberg Group age (2.714 Ga, Armstrong et al, 1991), the Schurwedraai alkali granite (2.052 Ga, Graham et al, 2005), and the Annas Rust dolerite (1.05 Ga, Reimold et al, 2000). The collar rocks surround a relatively flat, deeply eroded granitic gneissic core.…”