Comparative 14C and OSL dating of loess-paleosol sequences to evaluate post-depositional contamination of n-alkane biomarkers

Zech, M., Kreutzer, S., Zech, R., Goslar, T., Meszner, S., McIntyre, C. , Häggi, C., Eglinton, T., Faust, D. and Fuchs, M. (2017) Comparative 14C and OSL dating of loess-paleosol sequences to evaluate post-depositional contamination of n-alkane biomarkers. Quaternary Research, 87(1), pp. 180-189. (doi: 10.1017/qua.2016.7)

Abstract

There is an ongoing controversial discussion as to whether n-alkane lipid biomarkers—and organic matter of loess in general—reflect a synsedimentary paleoenvironmental/climate signal or whether they are significantly affected by postdepositional “contamination,” for example related to root and rhizomicrobial activity. In order to address this issue at our study site (the Middle to Late Weichselian loess-paleosol sequence Gleina in Saxony, Germany), we determined and compared radiocarbon ages of bulk n-alkanes and sedimentation ages, as assessed by optically stimulated luminescence (OSL) dating. The bulk n-alkanes of the four dated samples yielded calibrated 14C ages ranging from 24.1 to 49.7 cal ka BP (95.4% probability ranges). While the three uppermost n-alkane samples are well within the range or even slightly older than the OSL-inferred sedimentation ages, the lowermost n-alkane sample is slightly younger than the OSL ages. There is hence little or no evidence at our study site for n-alkanes in loess-paleosol sequences being significantly “contaminated” by deep subsoil rooting or microbial processes. We propose a 14C isotope mass balance calculation for estimating such contaminations quantitatively. Radiocarbon dating of bulk n-alkanes might have great potential for Quaternary research, and we encourage further comparative 14C and OSL studies.

• Item Type: Articles
• Additional Information: This study was funded by the German Research Foundation (DFG; FA 239/13-2 and ZE 844/1-1). The work of S. Kreutzer and M. Fuchs was gratefully funded by the DFG (FU 417/7-2). M. Zech and R. Zech also gratefully acknowledge the support provided by the Alexander von Humboldt-Foundation and the Swiss National Foundation (SNF 131670 and SNF 150590), respectively.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mcintyre, Dr Cameron
• Authors: Zech, M., Kreutzer, S., Zech, R., Goslar, T., Meszner, S., McIntyre, C., Häggi, C., Eglinton, T., Faust, D., and Fuchs, M.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Quaternary Research
• Publisher: Cambridge University Press
• ISSN: 0033-5894
• ISSN (Online): 1096-0287
• Published Online: 06 February 2017
• Copyright Holders: Copyright © 2017 University of Washington
• First Published: First published in Quaternary Research 87(1): 180-189
• Publisher Policy: Reproduced in accordance with the publisher copyright policy