gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1998.62A.2.147 Nd Isotopic Constraints on the Genesis of Archaean Tonalitic Gneisses from Southern Zimbabwe Luais B. Département des Sciences de la Terre, UMR-CNRS 5570, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 LYON Cedex 07, France Hawkesworth C. J. Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK 1998 62A 2 913 914 Copyright © 1998, The Mineralogical Society 1998