Quantification des flux sédimentaires et de la subsidence du bassin ...
Quantification des flux sédimentaires et de la subsidence du bassin ...
Quantification des flux sédimentaires et de la subsidence du bassin ...
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tel-00790852, version 1 - 21 Feb 2013<br />
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equivalent represented by UU-MU-upper part of LU1) has been <strong>de</strong>posited <strong>du</strong>ring the<br />
<strong>la</strong>ndward migration of the shoreline that led to the formation of the TRS.<br />
Figure 10. Scenario of the MSC <strong>de</strong><strong>du</strong>ced from the data avai<strong>la</strong>ble on<strong>la</strong>nd for the peripheral<br />
basins (see Bache <strong>et</strong> al., 2012) and for the central basins from the seismic interpr<strong>et</strong>ation which<br />
supports a precipitation of central evaporites only after the major sea-level fall (this study).<br />
The stages of this scenario are d<strong>et</strong>ailed in the text.<br />
Subdivisions of the MSC: see Figure 7.<br />
Figure 11. Variation of the Mediterranean sea level in the Gulf of Lions b<strong>et</strong>ween 6 and 5.30<br />
Ma encompassing the MSC (modified from Bache <strong>et</strong> al. (2012)). Successive major changes<br />
are estimated with respect to present-day sea level (noted “0”). The initial position of the<br />
paleoshoreline just before the catastrophic reflooding (step 2-III) has been estimated b<strong>et</strong>ween<br />
600 m and 900 m below the present sea level by (Bache <strong>et</strong> al., 2012) by subtracting the<br />
Pliocene and Quaternary subsi<strong>de</strong>nce <strong>de</strong><strong>du</strong>ced by (Rabineau <strong>et</strong> al., 2006) from its present-day<br />
position. The rapid increase in water <strong>de</strong>pth <strong>du</strong>ring step 2-III was thus b<strong>et</strong>ween 600 and 900 m.<br />
Solid and dashed b<strong>la</strong>ck lines are constrained by an increase of 600 m and 900 m respectively.<br />
Subdivisions of the MSC: see Figure 7.<br />
Figure 12. Numerical simu<strong>la</strong>tions constrained by the interpr<strong>et</strong>ation of seismic data supporting<br />
a precipitation of central evaporites after the major sea-level fall. The water budg<strong>et</strong> has been<br />
comprehen<strong>de</strong>d to intro<strong>du</strong>ce 1/ the existence of a d<strong>et</strong>rital episo<strong>de</strong> in re<strong>la</strong>tion with the maximum<br />
<strong><strong>de</strong>s</strong>iccation phase (step 2-I) prior to the precipitation of evaporites and 2/ a two-step<br />
reflooding (step 2-II <strong>du</strong>ring which evaporites <strong>de</strong>posited, and step 2-III, which en<strong>de</strong>d the<br />
MSC). The value of E-P has been chosen at 1.75 m 3 /m 2 /yr. River discharge = 7500 m 3 /s.<br />
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