TY - JOUR

T1 - Redox evolution during Eemian and Holocene sapropel formation in the Black Sea

AU - Wegwerth, Antje

AU - Eckert, Sebastian

AU - Dellwig, Olaf

AU - Schnetger, Bernhard

AU - Severmann, Silke

AU - Weyer, Stefan

AU - Brüske, Annika

AU - Kaiser, Jérôme

AU - Köster, Jürgen

AU - Arz, Helge W.

AU - Brumsack, Hans Jürgen

N1 - © 2017 Elsevier B.V. All rights reserved.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - 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 ~ 9,000 yr BP) have been intensively studied, the redox evolution during the last interglacial, the Eemian (~ 128,000-120,000 yr BP), remains largely unexplored. With its at least 3 °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 (~ 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.

AB - 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 ~ 9,000 yr BP) have been intensively studied, the redox evolution during the last interglacial, the Eemian (~ 128,000-120,000 yr BP), remains largely unexplored. With its at least 3 °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 (~ 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.

KW - Euxinia

KW - Interglacials

KW - Restricted basin

KW - Trace metals

KW - δFe

KW - δMo

UR - http://www.scopus.com/inward/record.url?scp=85033597648&partnerID=8YFLogxK

U2 - 10.1016/j.palaeo.2017.10.014

DO - 10.1016/j.palaeo.2017.10.014

M3 - Article

AN - SCOPUS:85033597648

VL - 489

SP - 249

EP - 260

JO - Palaeogeography, Palaeoclimatology, Palaeoecology

JF - Palaeogeography, Palaeoclimatology, Palaeoecology

SN - 0031-0182

ER -