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with the detachment of both carbonate and clastic– a post-Messinian thrust envelopment deformation,
terrigenous cover throughout regional subhorizon- marks the discontinuity between the internal thick-
tal surfaces. The bodies separated by these surfaces skinned part of the chain to the NW and the thin-
formed superposed duplex levels. The geometry of skinned external chain to the SE.
the thrust fronts (Figs. 3 and 11), from the
Cornaglia area to the Sicily offshore, points out The chain, between the Elimi ridge and offshore
the swinging of the transport direction trend from Sicily, is an embricate fan of sedimentary rocks,
SE to ESE. whose thrust planes root on the not involved
African crystalline basement.
The Upper Oligocene–Burdigalian terrigenous
successions (Numidian and equivalents) filled the The African crust is 25–30 km thick, a lower
foredeep of the Sardinian and Kabilian–Calabrian value than expected. The extensional structures do
chain (Fig. 9). These deposits were deformed as not appear significant in order to reduce original
roof thrust of the carbonate duplexes and emplaced crustal thickness. As a consequence, it is suggested
south-eastward over more external domains after here that most of the crustal thinning was inherited
the Langhian (Fig. 12). The Numidian nappes did from the Mesozoic Tethyan rifting.
not overpass the Egadi thrust front. In the outer
sector younger foredeep clastics (Lower to Middle Acknowledgements
Miocene) were stacked progressively south-eastward.
Many thanks to R. Catalano for constructive
Post-Messinian high-angle thrusts dissected the discussions, A.W. Bally for suggestions on the
Miocene thrust embricates, reactivating or cross- structural setting, and to the reviewers for their
cutting previous fault planes (Oldow et al., 1990), useful comments. Thanks also to S. Merlini and
with an in-sequence thrust envelopment. Pliocene– to ENI-AGIP for providing us with CROP and
Lower Pleistocene syntectonic basins later devel- commercial seismic profiles. This work has been
oped in the frame of Tyrrhenian opening. funded by CNR 96-98 (R. Catalano).
7. Discussion and conclusions References
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