Calibration and first application of biomarker and compound-specific isotope analyses in Mongolia

To enable more robust reconstructions of the paleoenvironmental/climatic conditions in Mongolia and to gain a convincing link between regional climate dynamics and pastoral empires beyond the ∼1,500 years limit of tree-ring records, well-dated high-resolution lake sediment records and more sensitive proxies are needed. Molecular biomarkers such as terrestrial n-alkanes and hemicellulose-derived sugars are promising proxies that can contribute to a better understanding of regional paleoenvironmental/climatic conditions. Especially the ability to analyze compound-specific isotope signatures (CSIS) provides source-specific environmental and climatic information. Although these proxies have been increasingly used and gained importance in the last decades in many regions of the world, no calibration nor paleo application of molecular biomarkers and CSIS exists in Mongolia so far. Therefore, this thesis aims to first apply biomarkers and CSIS for more robust paleoenvironmental/climatic reconstructions in Mongolia. In a first step, this thesis aims to calibrate the homolog patterns of terrestrial n-alkanes as well as the compound-specific carbon, hydrogen, and oxygen isotopes of n-alkanes and hemicellulose-derived sugars (δ13Cn-alkane, δ2Hn-alkane, and δ18Osugar) on modern reference material along two transects in Mongolia to evaluate their potential for paleoenvironmental/climatic reconstructions. In a second step, these proxies were applied in Late Holocene lake sediments from Telmen Nuur (Central Mongolia) and Khar Nuur (Mongolian Altai) to gain more robust and detailed paleoenvironmental/climatic information, especially in terms of Late Holocene moisture fluctuations.