Page 7 - Basin_formation_the Egadi

F . Gumhrri. A . Argnuni/Trcfonophysics 252 (1995)285-294 1LINE INVO-7

1 a n t i i n e with ouier aici- e x t e n i m

Fig. 9. Line INV089-7, eastem part. The pattem of reflection suggests that the fold, obsemable in the basin centre, is related to
contractional reactivation of a previous extensional fault. Fig. 3 for location.

5.2. Structural high (SH) subsidence of the adjacent basins, we believe that
large-scale contractional folding and uplift also con-
A structural high with a NW-SE strike separates tributed to its present setting.
the WS from the ES. It is 5 km wide in the south,
while in the north, where the two subbasins are 5.3. Eastern subbasin (ES)
almost joined, it narrows to less than 2 km. Line
INVO-7 (Fig. 8) shows a package of parallel reflec- It has a length of 30 km and a width of 10 km and
tions that defines a broad anticline with shallow its depth does not exceed 800 m. It is related to
dipping extensional faults affecting the sedimentary N-S- and NW-SE-trending extensional faults, ei-
cover of the SH. The strata bound by these faults dip ther east- or west-dipping, which divide the sub-
rather steeply to the southwest. As the faults have basin, along strike, into various half grabens having
very limited throw the tilting of the sedimentary opposite dips of the main extensional fault and oppo-
strata is not due to block rotation during extension site asymmetry of the basin infill. In places, how-
but, rather, to arching of the substrate. Therefore, ever, the basin appears to be symmetrical and with-
although this structural high might be only due to the out any bounding faults.

Fig. 10. Line G-69 illustrating two contractional stnictures affecting the sedimentary infill of the ES at different tirnes. The reverse fault at
the southem rnargin of the basin shows recent activity, while the anticline within the basin indicates earlier activity (see FIG. 11). The
triangle indicates the tie with line G-37. For location see Fig. 3.