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| Titel |
A major change in Pliocene Mediterranean hydrology, 3.55 - 3.35 Ma |
| VerfasserIn |
Nabil Khelifi, Michael Sarnthein  , Nils Andersen, Martin Frank, Dieter Garbe-Schönberg |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048581
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| Zusammenfassung |
| ODP Site 978 (1930 m w.d.) provides a highly resolved record of surface waters and West Mediterranean Deep Water in the Alboran Sea for the period 3.62–2.72 Ma (Khélifi et al., 2009; Khélifi, 2010). We found a ~4 psu increase in sea surface salinity from ~3.6 to 3.55 Ma, an event that occurred 100 kyr prior to a similar potential increase by ~1 psu in bottom water salinity (BWS) and by ~1 kg m-3 in bottom water density (BWD) from 3.5 to 3.35 Ma (if taking the Mg/Ca ratios of Cibicidoides spp. as face values of bottom water temperature). The latter joint salinity increase in surface and bottom waters records a significant aridification of Mediterranean summer climate. This event was coeval with the onset of more “steppic” vegetation in the Gulf of Lion (Fauquette et al., 1998). It was also documented at the northeast Atlantic continental margin (DSDP 548; 1250 m w.d.) up to Rockall Plateau (ODP 982; 1135 m w.d.) by a coeval singular and persistent increase in BWS by ~2-psu and in BWD by ~1 kg m-3 of Mediterranean Outflow Water (MOW) being traced by εNd values larger than –11. The outlined interval of strongly enhanced deep-water convection in the Mediterranean Sea and the resulting increase in MOW flow (estimated as ~1 Gt/day higher than today) record a major change in Mediterranean hydrology, that had no direct counterpart in Atlantic ocean history (Kleiven et al., 2002) and most likely originated from key changes in the African monsoon system, as shown by increasingly dry conditions depicted in terrestrial records from equatorial East Africa around that time (Trauth et al., 2007).
References
Fauquette, S., Guiot, J., and Suc J.-P., 1998: A method for climatic reconstruction of the Mediterranean Piocene using pollen data, Palaeogeo., Palaeoclim., Palaeoeco., 144, p. 183–201, doi: 10.1016/S0031-0182(98)00083-2.
Khélifi, N. (2010), Variations in Mediterranean Outflow Water and its salt discharge versus Pliocene changes in North Atlantic thermohaline circulation over the onset of Northern Hemisphere Glaciation, 3.7–2.6 Ma ago, PhD Thesis, 150 pp., Institute of Geosciences, Univ. of Kiel, Kiel, Germany, 04 June.
Khélifi, N., M. Sarnthein, N. Andersen, T. Blanz, M. Frank, D. Garbe-Schönberg, B.A. Haley, R. Stumpf, and M. Weinelt (2009), A major and long-term Pliocene intensification of the Mediterranean Outflow, 3.5–3.3 Ma ago, Geology, 37, 811–814, doi:10.1130/G30058A.1.
Kleiven, H.F., Jansen, E., Fronval, T., Smith, T.M., 2002. Intensification of Northern Hemisphere glaciations in the circum Atlantic region (3.5–2.4 Ma), ice-rafted detritus evidence. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 184, p. 213–223.
Trauth, M. H., M. A. Maslin, A. Deino, et al., 2007: High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution, Journal of Human Evolution, 53, pp. 475–486. |
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