Using Lipid Biomarkers and their Isotopic Composition to reconstruct the Late Pleistocene Paleoclimate of the Amazon Basin

Abstract

This thesis deals with the reconstruction of the late Pleistocene climate and vegetation history of the Amazon basin and is made up of three manuscripts: In the first manuscript biomarker based paleosalinity proxies are tested. It is shown that the stable hydrogen isotope composition of palmitic acid reflects the salinity conditions in the Amazon Outflow Plume, while the stable hydrogen isotope composition of alkenones is influenced by factors other than salinity. The second manuscript deals with the transport of long-chain n-alkanes in the Amazon River and its main tributaries. It is demonstrated that long-chain n-alkanes mainly originate from the lowland basin, contrasting the dominant inorganic sediment source in the Andes. The third manuscript deals with the application of plant wax proxies in a marine sediment core covering the late Pleistocene. It is shown that forest vegetation persisted through drier conditions during the last glacial maximum, while minor savanna expansion occurred during Heinrich Stadials.