Quantification des flux sédimentaires et de la subsidence du bassin ...

tel-00790852, version 1 - 21 Feb 2013
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generate subsidence in the central basins. However the observation of transgressive
ravinement surfaces in the Valencia Trough (García et al., 2011) and possibly in the Alboran
margin (Estrada et al., 2011) as well as the necessity of water inputs from oceans to
precipitate evaporites suggest a combination of subsidence and increase of the Mediterranean
sea-level (Bache et al., 2012). This context coupled with a high evaporation rate was
favorable to precipitate thick evaporites at the centre of the Mediterranean after the major
Messinian drawdown dated at 5.60 Ma (Butler et al., 1995; Butler et al., 1999; CIESM, 2008;
Clauzon et al., 1996; Riding et al., 1998) and before the catastrophic reflooding of the
Mediterranean at 5.46 Ma (Bache et al., 2012), followed by a continuing sea-level rise well-
documented at 5.332 Ma (Hilgen and Langereis, 1993; Lourens et al., 2004; Van Couvering et
al., 2000).
Here, we assume sufficient water inputs from ocean after the Messinian drawdown and before
the catastrophic reflooding. Recent numerical models suggest that such water input is
insufficient or unlikely to occur after the closure of the Rifian Corridor (Blanc, 2002; Garcia-
Castellanos et al., 2009; Govers, 2009; Govers et al., 2009). The numerous uncertainties on
models constraints (erodibility, uplift rate, climate data…) and the lack of alternative
conceptual scenarios consistent with our observations do not allow to discard our
assumptions. Loget et al. (2005) have shown that intense regressive erosion developed
inevitably in the Gibraltar area after the Messinian drawdown. It should be a likely process to
explain a continuous input of marine waters necessary to precipitate enough evaporites in the
desiccated Mediterranean Basin.
In the Eastern Mediterranean, wave ravinement surfaces comparable to the TRS observed in
the Gulf of Lions have been observed off the Nile Delta in the interfluves bordering the Abu
Madi canyon, where it contrasts sharply with the lowermost part of the canyon fill (Dalla et
al., 1997). A series of flat ravinement surfaces have also been identified in the Levantine
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