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6 F. NIGRO

Fig. 4. Main neotectonic brittle lineaments charac-
terising mainland Sicily

with different kinematic indicators (dip- and strike-

slip). The fold systems that have also involved the

outcropping Plio-Pleistocene sequences appear as

large-scale and gentle en-echelon systems, relatable

to some buried and emergent transcurrent faults.

Fig. 4 shows a synthesis of aerophotographical ob-

servations in Sicily and the main brittle neotectonic Fig. 5. Geòlogical map and sections across the Nebrodi Mts. tectonic
trends of the lineaments characterising the island. edifice ofwhich the thrust system (<i>) involving Pliocene sequences ("Trubi")
Figs. 7 and 8 show some examples, based on field is recognised. l - Early Pliocene "Trubi" Fm.; 2- Oligocene-Early Miocene
observations, of recent structures characterising flysch-Iike Reitano Fm.; 3 - Cretaceous-to-Paleogene Sicilidi terranes; 4 -
western and eastem Sicily. The regional trend of Oligocene-Early Miocene Numidian Flysch; 5- main thrusts

brittle structure allows to consider the whole system as

deep-seated down to the crustallevels that represent the Af- Fig. 7B represents the neotectonic structural setting of

rican regional monoclìne (Fig. 3). the Palermo area. The sketch illustrates:

Several examples based on field observations allow to -an E-W trending dip-slip fault system cutting a sand-

hypothesise the presence of important crustal structural ele- stone sequence of Sicilian age (G. truncatulinoides excelsa

ments in the Sicily mainland. biozone);

The example in Fig. 7A is a sketch of large-scale - a previous extensional fault system represented by a

neotectonic structures involving the previously deformed N-S trending symmetric graben (in the Monreale area);

Western Sicily Belt. Two NW-SE to E-W trending high an- -an E-W trending asymmetric graben (in the Belmonte

gle reverse (transpressive) faults that have produced some Mezzagno area), where two opposite-verging structures are

positive flower structures (Kumeta and Busambra Mts.) are separated by a NNW-SSE trending high angle strike-slìp

represented in the figure. In these areas, the most recent se- "transfer" fault. Comparison with marine data from interpre-

quences involved in the deformation related to the positive tation of high-resolution multichannel seismic reflection

flower structures are Late Pliocene (G. iriflata biozone) and profiles (Agate et al., 1993) makes it possible to date the

appear to be not older than 2.4 Ma, and certainly not earlier earlìest extensional deformation at between 1.2-1.4 and 0.8

than 1.2-1.4 Ma in the Calatubo area, as ìllustrated by Agate Ma.

et al. (1993) in the Northern Sicily offshore areas. Fig. 7C shows a NE-SW trending large scale gentle en-

echelon fold system involving Pleistocene marine se-

quences. These structures could be interpreted as a shallow

expression of an E-W trending buried right-lateral transcur-

rent fault, which northwards has produced a buried positive

flower structure and a system of partially emergent syntethic

macroriedels (Castelvetrano area). The age of the most re-

cent successions involved in the folding is Lower Pleisto-

cene (G. cariacoensis-G. truncatulinoides excelsa bio-

zones).

In the Sicani Mts. Area, it is possible to suppose the

presence of a partially buried shear zone. The right-lateral

displacement ofthis crustal structure could have produced a

Fig. 6. Example of post-Messinian thrusting recognised in the system of E-W trending, high-angle branched transpressive
more internai mainland Sicily areas (Peloritani Mts.). Pz- pre-Tri- faults and associated meridionalls-trending riedels. Outcrop
assic Aspromonte Unit (high-grade crystalline rocks); Me- Mess- data confirm this supposition. Fig. 7D shows an analogous
inian gypsum configuration. In this area, outcropping Mesozoic sequences