Kusch, Stephanie ORCID: 0000-0002-2708-4975, Rethemeyer, Janet, Hopmans, Ellen C., Wacker, Lukas and Mollenhauer, Gesine ORCID: 0000-0001-5138-564X (2016). Factors influencing C-14 concentrations of algal and archaeal lipids and their associated sea surface temperature proxies in the Black Sea. Geochim. Cosmochim. Acta, 188. S. 35 - 58. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1872-9533

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Abstract

Understanding the preservation and deposition history of organic molecules is crucial for the understanding of paleoenvironmental information contained in their abundance ratios such as U-37(k') and TEX86 used as proxies for sea surface temperature (SST). Based on their relatively high refractivity, alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) can survive postdepositional processes like lateral transport, potentially causing inferred SSTs to be misleading. Likewise, selective preservation of alkenones and GDGTs may cause biases of the SST proxies themselves and can lead to decoupling of both proxy records. Here we report compound-specific radiocarbon data of marine biomarkers including alkenones, GDGTs, and low molecular weight (LMW) n-fatty acids from Black Sea sediments deposited under different redox regimes to evaluate the potentially differential preservation of both biomarker classes and its effect on the SST indices U-37(k') and TEX86. The decadal Delta C-14 values of alkenones, GDGTs, and LMW n-fatty acids indicate similar preservation under oxic, suboxic, and anoxic redox regimes and no contribution of pre-aged compounds, e.g., by lateral supply. Moreover, similar C-14 concentrations of crenarchaeol, alkenones, and LMW n-fatty acids imply that the thaumarchaeotal GDGTs preserved in these sediments are produced in the euphotic zone rather than in subsurface/thermocline waters. However, we observe biomarker-based SSTs that strongly deviate (Delta SST up to 8.4 degrees C) from in situ measured mean annual SSTs in the Black Sea. This is not due to redox-dependent differential biomarker preservation as implied by their Delta C-14 values and spatial SST pattern. Since contributions from different sources can largely be excluded, the deviation of the U-37(k') and TEX86 proxy-derived SSTs from in situ SSTs requires further study of phylogenetic and other yet unknown environmental controls on alkenone and GDGT lipid distributions in the Black Sea. (C) 2016 Elsevier Ltd. All rights reserved.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Kusch, StephanieUNSPECIFIEDorcid.org/0000-0002-2708-4975UNSPECIFIED
Rethemeyer, JanetUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hopmans, Ellen C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wacker, LukasUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mollenhauer, GesineUNSPECIFIEDorcid.org/0000-0001-5138-564XUNSPECIFIED
URN: urn:nbn:de:hbz:38-265210
DOI: 10.1016/j.gca.2016.05.025
Journal or Publication Title: Geochim. Cosmochim. Acta
Volume: 188
Page Range: S. 35 - 58
Date: 2016
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication: OXFORD
ISSN: 1872-9533
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
ORGANIC-MATTER PRESERVATION; MARINE-SEDIMENTS; SEASONAL VARIABILITY; ANAEROBIC OXIDATION; TETRAETHER LIPIDS; OXIC DEGRADATION; RADIOCARBON AGES; MEMBRANE-LIPIDS; RESERVOIR AGES; CHLOROPHYLL-AMultiple languages
Geochemistry & GeophysicsMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/26521

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