Comment on: New PGE and Re/Os-isotope data from lower crustal sections of the Vredefort dome and a reinterpretation of its "crust-on-edge" profile: R.J. Hart, I. McDonald, M. Tredoux, M.J. de Wit, R.W. Carlson, M. Andreoli, D.E. Moser and L.D. Ashwal (Vol. 207 (1/2), 173-184)

Abstract

Ever since Slawson (1976) suggested that the Archaean crystalline basement rocks in the core of the Vredefort dome southwest of Johannesburg might represent “crust-on-edge”, debate has existed about the extent to which the deep crust was exhumed by the ~2.02 Ga, impact-induced doming event. In a suite of papers since 1981, Hart and co-workers (Hart et al. , 1981; 1990a; b; 2004; De Wit et al. , 1992; Tredoux et al. , 1999; Moser et al. , 2001; Flowers et al. , 2003) postulated that doming (and subsequent erosion) exposed a complete section through the crust of the central Kaapvaal craton, and that even rocks of the uppermost mantle are exposed near the centre of the dome. Their argument has been compiled based on: Geophysical evidence has also been used in support of this model - a positive Bouguer gravity anomaly in the central parts of the dome (Maree, 1944; Stepto, 1990) was interpreted by Hart et al. (1990b) as indicative of the existence of dense upper mantle rocks close to surface, …