Organic geochemical evidence of late Pleistocene-Holocene environmental changes in the Lake Balaton region (Hungary)

This paper presents organic geochemical records and a combined interpretation of organic geochemical and palaeoecological data for a late Pleistocene-Holocene shallow lake sequence. Abundance, bulk chemical composition and sources of the organic matter (OM), as well as the relative contribution of the labile and resistant bio- and geo-macromolecules, were determined on 46 sediment samples. Lipids isolated from selected samples, representing the lowest and highest water levels, were analyzed. Integration of the organic geochemical and palaeoecological records suggests that climate exerted the primary control on the amount and quality of the OM preserved. The relative contribution of the labile (fresh plant and litter) and resistant (lignin and cellulose) bio-macromolecules, immature geo-macromolecules (humic substances) and mature refractory geo-macromolecules, and the degree of preservation of the primary biomass, calculated from mathematical deconvolution of Rock-Eval pyrograms, allowed the distinction of three and five zones, related mainly to water level fluctuation, within the late Pleistocene and Holocene sequences, respectively.