Large-scale response of the Eastern Mediterranean thermohaline circulation to African monsoon intensification during sapropel S1 formation

T. Tesi, A. Asioli, D. Minisini, V. Maselli, G. Dalla Valle, F. Gamberi, L. Langone, A. Cattaneo, P. Montagna, F. Trincardi

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Abstract

The formation of Eastern Mediterranean sapropels has periodically occurred during intensification of northern hemisphere monsoon precipitation over North Africa. However, the large-scale response of the Eastern Mediterranean
thermohaline circulation during these monsoon-fuelled freshening episodes is poorly constrained. Here, we investigate the formation of the youngest sapropel (S1) along an across-slope transect in the Adriatic Sea. Foraminifera-based
oxygen index, redox-sensitive elements and biogeochemical parameters reveal – for the first time – that the Adriatic S1 was synchronous with the deposition of south-eastern Mediterranean S1 beds. Proxies of paleo thermohaline
currents indicate that the bottom-hugging North Adriatic Dense Water (NAdDW) suddenly decreased at the sapropel onset simultaneously with the maximum freshening of the Levantine Sea during the African Humid Period. We
conclude that the lack of the “salty” Levantine Intermediate Water hampered the preconditioning of the northern Adriatic waters necessary for the NAdDW formation prior to the winter cooling. Consequently, a weak NAdDW limited
in turn the Eastern Mediterranean Deep Water (EMDWAdriatic) formation with important consequences for the ventilation of the Ionian basin as well. Our results highlight the importance of the Adriatic for the deep water ventilation
and the interdependence among the major eastern Mediterranean water masses whose destabilization exerted firstorder control on S1 deposition.
Original languageEnglish
Pages (from-to)139-154
Number of pages16
JournalQuaternary Science Reviews
Volume159
Early online date7 Feb 2017
DOIs
Publication statusPublished - 1 Mar 2017

Keywords

  • Sapropel S1
  • Mediterannean Sea
  • African monsoons
  • Anoxia
  • Thermohaline circulation

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    Tesi, T., Asioli, A., Minisini, D., Maselli, V., Dalla Valle, G., Gamberi, F., Langone, L., Cattaneo, A., Montagna, P., & Trincardi, F. (2017). Large-scale response of the Eastern Mediterranean thermohaline circulation to African monsoon intensification during sapropel S1 formation. Quaternary Science Reviews, 159, 139-154. https://doi.org/10.1016/j.quascirev.2017.01.020