Volcanology of the diatreme-rich carbonatitic Gross Brukkaros volcanic field and of the nearby Gibeon kimberlite province, Namibia - Lorenz, V.; Kurszlaukis, S.; Stachel, T.; Brey, G.; Stanistreet, I.G.; Franz, L. (International Kimberlite Conference: Extended Abstracts, 1995)