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

tel-00790852, version 1 - 21 Feb 2013
A) Zoom on Seismic Profile LRM16 in TWTT (s) and interpretation of Miocene and
Pliocene-Quaternary strata. Wells Tramontane is on the profile. Note the deformation
of plio11 refelctor and q10 reflector just above a major deeper Fault F1. Interpretation
of Miocene strata slightly modified from Bache, 2008. Another deformation can be
suspected in the landward most part of the profile See position of profile and Faults on
Figure B.
B) Mapping of Major Faults and thickness of Miocene deposits (without messinian
deposits) (in seconds twtt) from Bache, 2008. The thick line represent the position of
Seismic Profile LRM16 shown in A). Major Fault F1 is localised near the Tramontane
well (green dot) on the profile.
Figure 10-Rectot.ai
Seismic Profile LRM18 in depth (m) used for calculation of 2D subsidence along the profile.
Black pins on top show cross-lines. The inner part of the shelf (Km 0 to Km 36) has been
reconstructed to correct the effect of post-depositional deformation (large scale deformation).
In this configuration topsets of reflectors p1 to present day sea-floor are well approximated to
straight lines both on the inner and outer part of the shelf. All lines are inclined seaward, their
inclinations increase with the age of reflectors. All lines have also a common rotation point
which is located 13 km landward of present-day coast. The tilting of the margin from p1 to
present day can be measured directly on the profile, it reaches 1280 m at Km 70 from the
coast. Considering that the first clinoform p1 can be dated as early Pliocene (just after the
Zanclean reflooding) we estimated its age between 5.3 and 5 Ma. This allows us to calculate a
subsidence rate going from 0 m/Ma at -13 Km landward of the coast to 240-255 m/Ma at Km
70 seaward from the coast (near the upper slope).
Figure 11 – A) ECORS profile converted in depth (using previous velocity law-figure 06).
Dm : discontinuity at the base of Messinian deposits; LU0, LU1 : lower unit of messinian age
; MU : mobile unit (salt) ; according to Bache et al., 2009. For a more detailed interpretation
of Miocene and messinian deposits see recently published paper from Bache et al., 2009 ;
Bache et al., 2010. The vertical dashed red line indicates a change in the direction of the
seismic profile. B) Approximation of the messinian surface to the base of salt with a straight
line inclined seaward. The line has a rotation point which is located 22 km landward of
present-day coast.