18O Analyses of bulk lipids as a novel palaeoclimate tool in loess research - a pilot study

The analysis of the stable oxygen isotopes ¹⁸O and ¹⁶O has revolutionised palaeoclimate research since the middle of the last century. Particularly, ¹⁸O of ice cores from Greenland and Antarctica is used as a palaeotemperature proxy and ¹⁸O of deep-sea sediments is used as a proxy for global ice volume. Important terrestrial archives to which ¹⁸O as palaeoclimate proxy is successfully applied are speleothems, lake sediments or tree rings. By contrast, ¹⁸O applications to loess-palaeosol sequences (LPSs) are scarce, despite for instance a compound-specific ¹⁸O analytical tool for sugar biomarkers was developed and presented already years ago (Zech et al., 2014). Here we present a first continuous ¹⁸O record (n=50) for the LPS Crvenka in Serbia, SE Europe, spanning the last glacial-interglacial cycle. From a methodological point of view, we took advantage of a recently proposed palaeoclimate/-hydrological tool/proxy based on bulk ¹⁸O analyses of plant-derived lipids. The ¹⁸O lipid values range between −10.2‰ and +23.0‰ and are systematically more positive in the interglacial and interstadial (paleo-)soils compared to the loess layers. In our presentation, we compare our ¹⁸O lipid record from the LPS Crvenka with the marine oxygen-isotope stages as well as with the Greenland ¹⁸O ice core records revealing the famous Dansgaard-Oeschger events (stadials and interstadials). Concerning the interpretation of our LPS ¹⁸O lipid record, we will discuss several influencing factors, such as temperature-control on ¹⁸O, evaporative leaf water enrichment, post-sedimentary effects and pool-effects.

References

Labahn, J., Bittner, L., Hirschmann, P., Roettig, C., Burghardt, D., Glaser, B., Marković, S. and Zech, M., 2022. ¹⁸O analyses of bulk lipids as novel paleoclimate tool in loess research – a pilot study. E&G Quaternary Science Journal 71, 83-90.

Zech, M., Mayr, C., Tuthorn, M., Leiber-Sauheitl, K. and Glaser, B., 2014. Reply to the comment of Sternberg on "Zech et al. (2014) Oxygen isotope ratios (¹⁸O/¹⁶O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy I: Insight from a climate chamber experiment”. GCA 126, 614-623. Geochimica et Cosmochimica Acta 141, 680-682.