gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1998.62A.1.112 Early Diagenesis of Organic Matter from Higher Plants in a Malagasy Peaty Marsh. Application to Environmental Reconstruction During the Sub-Atlantic Bourdon S. Laggoun-Défarge F. Maman O. Disnar J.-R. Guillet B. UMR CNRS 6531, Université d'Orléans, BP 6759, 45067 Orléans Cedex 2, France Derenne S. Largeau C. UMR CNRS 7573, ENSCP, 75231 Paris Cedex 05, France 1998 62A 1 211 212 Copyright © 1998, The Mineralogical Society 1998