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RHEGMATIC-LIKE BASINS IN SICILY 17

Al eulerian pole A2 A3 shear/mantle up extension

"~~, t N
overlap
\'

overall eastward
drifting

Bl 5-4 Myr 3-2 Myr B3

Fig. 18. A. Kinematic mode! of stretching due to mega-shear movements of blocks moving on a sphere. A l is the initial stage. The
progressive movemcnt of the right part of the square induces a progressive rotation (scheme A2 an d A3), with severa! overlapping and
extensions areas. B. Hypothetical mode! of kinematic evolution of the Tyrrhenian area during the Plio-Pleistocene. During the Early
Pliocene (scheme B l) in the back-area of the N-S trending half-arched Sicilian-Apcnninic suture zone an important right-hand
transcurrent crustal fault (Egadi Fault and its notthward prolongation) bounds eastward the Sardinia Block. Some mega-riedels were
activated during this stage (e.g. the Selli Line), when an overall extensional status characterised the proto-Tyrrhenian area. The notthward
prosecution ofthe African "advancement" (scheme B2) produced a progressively more and more arched shape ofthe suture zone and the
evolution ofthe Selli structuralline in a sphenochasm-like structure. The prosecution ofthe African plate motion (scheme B3) accentuates
the overall E- W and/or NW-SE trending extension of the Tyrrhenian area and suppotts the eastward formati an of further rhegmatic-like
basins (e.g. the Marsili Basin). There are E-W trending transpressional structures, with associateci NW-SE Riedel systems, cutting the
Northern Sicilian Belt progressively toward the east. The progressive t1exural loading of the Sicilian Belt, together with the right-hand
motion of the "Egadi Fault" in the Pelagian area, contributes to the southern crustal thinning and rifting processes in the Pantelleria
rhegmatic-like basin

Sicanian-Gela Thrust Systems and the External Calabrian ated the overall E-W and/or NW-SE trending extension of
Are (Figs. 3 and l 0). the Tyrrhenian area. lt supported the eastward formation of
further rhegmatic-like basins (e.g. the Marsili Basin, Fig.
The very strong uplift ofthe Northem Sicilian Belt dur- 17) and other small sphenochasms over the very arched ar-
ing the last 2-3 Ma, and the activation ofthe northern Sicily eas of the subduction complex (Calabri an Are, Fig. JSB3),
LANFs system (see Fig. 12), could be explained by the pres- with a clockwise rotation ofthe Maghrebian terrains in Sic-
ence of a deep (intermediate?) necking leve! below the ily (Channel et al., 19SO); and widespread NNE-SSW and
northern side of the Sicily shelf (Fig. 15). The intraplate E-W trending deep structures in the Apennines (Lavecchia
stresses related to the northward motion of the Africa plate, et al., 19S4). The asociated progressive flexural loading of
and to the Tyrrhenian mantle uplift (and as a result of the Sicilian Belt, due to the out-of-sequence "Gela Thrust
oblique convergence of the Tyrrhenian-lonian complexes) System", together with the effects of the overall right-hand
in the Sicilian Belt, might bave activated the recognised motion of the "Egadi Fault" in the Pelagian area, probably
E-W trending right-lateral crustal transpressive fault sys- contributed to the southern crustal thinning and rifting proc-
tems (Figs. 7A, 7C, 7D, SD and SE) and, progressively to- esses in the Pantelleria rhegmatic-like basin (Carbone et al.,
wards the east, the associated NW-SE trending megariedel 19S2; Grasso & Reuther, 19SS; Grasso et al., 1990).
system (Figs. 7C, SA and SB, see also Figs. 13 and 14).

The prosecution of the African plate motion accentu-

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