EGU21-8853
https://doi.org/10.5194/egusphere-egu21-8853
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Climate and carbon cycle changes drive the hydrographic configuration of the eastern Mediterranean through the Tortonian-Messinian Transition

Evangelia Besiou1, George Kontakiotis1, Assimina Antonarakou1, Andreas Mulch2,3, and Iuliana Vasiliev2
Evangelia Besiou et al.
  • 1National and Kapodistrian University of Athens, Athens, Greece (wwweua@hotmail.com)
  • 2Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, D-60325 Frankfurt am Main, Germany
  • 3Goethe University, 60438 Frankfurt am Main, Germany

The Late Miocene has been considered one of the most climatically stable periods of the Cenozoic, time span characterized by minor long-term cooling and ice growth. Especially, the Tortonian-Messinian Transition is recognized as a priority for paleoenvironmental reconstruction and climate modelling due to the significant paleoenvironmental changes preceding the Messinian Salinity Crisis (MSC; 5.97-5.33 Ma). Here, we present stable oxygen (δ18O) and carbon (δ13C) isotopes measured on benthic and planktonic foraminifera from Potamida section (Crete Island, eastern Mediterranean). The δ18O results indicate a decoupling between the surface and the bottom water column starting before the Tortonian-Messinian boundary. The difference between planktonic and benthic oxygen isotope signals (Δδ18O) further provides an estimate of the degree of water column stratification during that time. The δ13C data indicate a generally trend towards lighter values as an excellent illustration of the Late Miocene Carbon Isotope Shift (LMCIS; 7.6-6.6 Ma) due to progressive restriction of the Mediterranean basin, with the exception of the 7.38-7.26 Ma time interval where significantly heavier δ13C values are documented in both records. Such changes in carbon cycle seem to be most pronounced in the planktonic foraminiferal record (surface waters) through a 6-cycle development indicative of a cyclic productivity pattern during the latest Tortonian. The entire record is substantiated by sea surface temperature (SST) estimates based on TEX86 biomarker based proxy. The reconstructed SST record shows that a warm phase characterized the late Tortonian sea surface (~27⁰C), time followed by a strong, steady cooling starting with earliest Messinian, when the SSTs dropped to values as low as 20⁰C. The outcome of the combined stable isotope and biomarker based SST data hint to increased salinity in the surface waters already before the Messinian, while at the Tortonian-Messinian Transition, the conditions in the surface waters changed towards cooler (~24⁰C) and normal salinity conditions.

How to cite: Besiou, E., Kontakiotis, G., Antonarakou, A., Mulch, A., and Vasiliev, I.: Climate and carbon cycle changes drive the hydrographic configuration of the eastern Mediterranean through the Tortonian-Messinian Transition, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8853, https://doi.org/10.5194/egusphere-egu21-8853, 2021.

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