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

Type Article
Date 2017-03
Language English
Author(s) Tesi T.1, Asioli A.2, Minisini D.3, Maselli V.4, Valle G. Dalla1, Gamberi F.1, Langone L.1, Cattaneo AntonioORCID5, Montagna P.1, Trincardi F.1
Affiliation(s) 1 : CNR, CNR ISMAR, Ist Sci Marine, Via Gobetti 101, I-40129 Bologna, Italy.
2 : CNR, IGG, Via G Gradenigo 6, I-35131 Padua, Italy.
3 : Shell Int Explorat & Prod Inc, 3333 Highway 6 South, Houston, TX 77082 USA.
4 : Univ Aberdeen, Dept Geol & Petr Geol, Kings Coll, St Marys Bldg, Aberdeen AB24 3UF, Scotland.
5 : IFREMER, Geosci Marines EDROME, Ctr Brest, BP70, F-29280 Plouzane, France.
Source Quaternary Science Reviews (0277-3791) (Pergamon-elsevier Science Ltd), 2017-03 , Vol. 159 , P. 139-154
DOI 10.1016/j.quascirev.2017.01.020
WOS© Times Cited 24
Keyword(s) Sapropel S1, Mediterranean sea, African monsoons, Anoxia, Thermohaline circulation
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 first-order control on S1 deposition.
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Tesi T., Asioli A., Minisini D., Maselli V., Valle G. Dalla, Gamberi F., Langone L., Cattaneo Antonio, 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. Publisher's official version : https://doi.org/10.1016/j.quascirev.2017.01.020 , Open Access version : https://archimer.ifremer.fr/doc/00371/48205/