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Citation
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HERO ID
4270240
Reference Type
Journal Article
Title
Redox evolution during Eemian and Holocene sapropel formation in the Black Sea
Author(s)
Wegwerth, A; Eckert, S; Dellwig, O; Schnetger, B; Severmann, S; Weyer, S; Brueske, A; Kaiser, J; Koester, J; Arz, HW; Brumsack, HJ
Year
2018
Is Peer Reviewed?
1
Journal
Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN:
0031-0182
Volume
489
Page Numbers
249-260
DOI
10.1016/j.palaeo.2017.10.014
Web of Science Id
WOS:000416501000019
Abstract
The Black Sea repeatedly experienced major hydrographic changes during glacial-interglacial transitions, with alternating limnic and brackish stages. While the redox conditions during the present Holocene brackish period (since similar to 9,000 yr BP) have been intensively studied, the redox evolution during the last interglacial, the Eemian (similar to 128,000-120,000 yr BP), remains largely unexplored. With its at least 3 degrees C warmer climate and an up to 10 m higher global sea level, the Eemian could open a window into the future development of the Black Sea. This study provides a detailed comparison of the Black Sea redox evolution during Eemian and Holocene sapropel formation. We show that the redox conditions and associated geochemical processes in the Black Sea water column can strongly deviate from the Holocene when sea level and climate conditions are different. Mo/Al and Re/Mo as well as Mo and Fe isotope proxies record a comparatively uniform rise of the Eemian redoxcline culminating in pronounced euxinia. This scenario strongly contrasts with weaker euxinic conditions during the Holocene Unit II sapropel (similar to 8,000-2,500 yr BP). Higher Mo/TOC ratios during the Eemian and Mo inventory considerations suggest a higher Eemian Mo availability, possibly due to an improved connection to the Mediterranean Sea. We conclude that higher temperatures, productivity, sea level -associated salinity changes, and corresponding higher sulphide levels were ultimately responsible for enhanced trace metal enrichment during the Eemian Black Sea sapropel stage.
Keywords
Interglacials; Restricted basin; Euxinia; Trace metals; delta Mo-98; delta Fe-56
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Molybdenum
Litsearch 2018
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