PLANT WAX BIOMARKERS IN FLUVIAL-LACUSTRINE SEDIMENTS FROM EAST AFRICA: PRESERVATION, ABUNDANCE, AND FEASIBILITY FOR PALEOCLIMATE RECONSTRUCTIONS
The heterogeneity of fluvial-lacustrine deposits requires assessment of biomarker preservation and abundance prior to generating isotopic records for paleoenvironmental reconstructions. We analyzed fluvial-lacustrine samples from the Omo-Turkana and Awash Basins to assess the feasibility of generating continuous isotopic records of vegetation and hydroclimate. We measured the distribution, abundance, and where possible, preliminary δD and δ13C values in n-alkanes and n‑alkanoic acids. The carbon preference index, which serves as an indicator for biomarker preservation, suggests suitable preservation in most samples. Abundances vary significantly in both n-alkanes and n‑alkanoic acids, with higher biomarker concentrations in lacustrine versus fluvial samples. About two-thirds of samples can be analyzed for δD values, whereas nearly all can be analyzed for δ13C values based on minimum analytical requirements. In many n-alkane samples, a large unresolved complex mixture is present, which can interfere with isotopic measurement unless further steps are taken to clean up the sample. Our results indicate fluvial-lacustrine deposits are promising biomarker archives, but illustrate careful screening and assessment are necessary.