Page 6 - Basin_formation_the Egadi

290 F . Gumheri. A. Argriuni / Tecronophysic.~252 (19951285-294

Fig. 7. Line INVOS9- 16 crossing the southernmost part of the WS. Note the change in polarity of the half graben with respect to line G-35
(Fig. 5 ) and the lack of contractional features. See Fig. 3 for location.

tively, in the sediment input during contraction. In the basin and the seismic units previously recognised
the upper part of unit B wedging of reflections seems can not be traced on the profile. The wedging of
to indicate extensional activity of the boundary fault. reflections within the basin infill testifies continuous
This extension was mainly active during the deposi- activity of the extensional fault. In this portion of the
tion of unit C. WS the basin infill is not affected by contractional
structures and the unconformities inside the basin
The southemmost half graben (Fig. 7) is bound by infill are likely due to intermittent activity of the
an east-dipping NNW-SSE-trending fault which main extensional fault or, alternatively, to pulses of
lowers the base of the Pliocene to 2.8 s.t.w.t. A sediment input.
transfer zone separates this half graben by the rest of

Fig. 8. Line INV089-7, western part. The structural high appears as a broad anticline with low-angle extensional faults affecting the
sedimentary succession. Location in Fig. 3.