Nature and degradation mode of organic matter in Tritrivakely peaty marsh (Madagascar). Application to environmental reconstruction during the last 2300 years

Abstract : The petrographical and geochemical study of superficial peat and living higher plants of Tritrivakely peaty marsh (Madagascar) has enabled the determination of (1) origin of peat organic matter, (2) some parameters which account for variations in depositional conditions, especially water table level, and their effects on organic matter preservation of accumulated peat. Moreover, transmission electron microscopy on ultrathin sections histochemically stained for phenols and polysaccharides revealed the distribution of these components in plant tissues and amorphous organic matter, and enabled their evolution during early diagenesis to be followed. It appears that the phenolic parts are nanoscopically amorphous, while polysaccharidic laminae are bioresistant, and probably belong to plant cell walls.