Proxy data of Holocene and Eemian sapropels in the Black Sea

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.