Page 10 - 05 albarello

Dario Albarello, Enzo Mantovani and Marcello Viti

Fig. 6. Strain field associated to the displacements field shown in fig. 5. Principal strain directions are re-
ported for a number of points representative of the local strain field. The length of arrows is proportional to lo-
ca! strain values, following the scale reported in the inset. Converging and diverging arrows respectively indi-
cate E1 and E3 (maximum and minimum principal strain axis respectively) directions. Geographical contours
and geometry of structural domains are reported for reference. North is upward.

ment roughly corresponds to the drifting of zone, which simulates the consumption of
Africa during a time span of 150 years, in ac- thinned Ionian lithosphere beneath the Cala-
cord with the kinematic pattem proposed by brian are (Rossi and Sartori, 1981; Finetti and
Mantovani et al. (1993, 1996) and Albarello Del Ben, 1986; Bousquet and Philip, 1986).
et al. (1993, 1995).
In the wake of the Calabrian blocks, exten-
lt can be noted that boundary conditions are sion occurs at the boundary with the Tyrrhe-
accommodated by the lateral escapes of crustal nian area (see fig. 6). The extensional rate in
wedges in the zone of maximum compression. this zone, about 2.0 mm/yr ("'30 cm in 150
The Calabrian wedges extrude roughly east- years, fig. 5), is compatible with the Quater-
wards. This motion is allowed by the shorten- nary extensional rate observed in Southem
ing of the «weak» boundary with the Ionian Calabria (Westaway, 1993), with the strain

842