Page 1 - 05 albarello

ANNALI DI GEOFISICA, VOL. XL, N. 4, August 1997

Finite element modelling
of the recent-present deformation pattern

in the Calabrian are
and surrounding regions

Dario Albarello, Enzo Mantovani and Marcello Viti
Dipartimento di Scienze della Terra, Università di Siena, ltaly

Abstract

An attempt is made to quantify the implications of the hypothesis that the recent-present deformation pattem
in the Calabrian are and the adjacent African margin is mainly determined by horizontal tectonic forces in-
duced by the relative convergence of the confining blocks (Africa and Adriatic). Modelling of present-day tec-
tonic processes is carried out by means of a 2D finite element scheme involving elastic shells in a piane stress
approximation. On the assumption that tectonic processes are strongly influenced by the presence of major dis-
continuities, the model includes zones where most deformations can concentrate. Convergent and divergent
boundaries are simulated by narrow belts having elastic parameters lower than those in the surrounding re-
gions. Transform boundaries are reproduced by orthotropic elements. Kinematic boundary conditions are im-
posed to simulate the relative convergence between Africa and the Adriatic. Numerical experiments show that
this convergence causes the lateral escape of crustal wedges in the Calabrian are and the adjacent African mar-
gin (Sicily). The resulting microplate kinematics can account for the complex distribution of compressional,
tensional and transcurrent deformations actually observed.

Key words geodynamic modelling - finite ele- Ben, 1986; Bigi et al., 1989; Van Dijk and
ments- Mediterranean Okkes, 1991; Reuther et al., 1993).

l. Introduction The distribution of recent (Quatemary)
compressional, tensional and transcurrent fea-
The eastemmost sector of the Maghrebian tures delineates a strong lateral heterogeneity
belt, with the related Iblean foreland zone, and of the strain field. The central sector of the
the Calabrian are (fig. l) has been affected by Sicily Channel has been affected by a SW-NE
intense tectonic activity during the recent evo- extension in the framework of strike slip tec-
lution, as indicated by neotectonic deforma- tonics (see, Celio et al., 1985; Finetti and Del
tions, intense seisrnicity and volcanism (see, Ben, 1986). Sinistra! transpressional move-
e.g., Barbano et al., 1978; Beccaluva et al., ments are observed along the Egadi fault (EF
1982; Cristofolini et al., 1985; Finetti and Del in fig. l) separating the Adventure block (AD)
from the adjacent Maghrebian belt (Reuther
Mailing address: Dr. Dario Albarello, Dipartimento di et al., 1993), and along the Sciacca fault (SF),
Scienze della Terra, Settore di Geofisica, Università di between the Adventure block and the Gela basin
Siena, Via Banchi di Sotto 55, 53100 Siena, Italy; e-mail: (GB). A system of dextral transform faults
dario@ibogfs.df.unibo.it (Comiso-Scicli, CF) is observed at the bound-
ary between the lblean block (IB) and the Gela
basin (Antonelli et al., 1988; Argnani et al.,

833