Simulation of collision zone segmentation in the central Mediterranean

Abstract

Collision processes between the African and European plates in the Ionian Sea offshore Calabria and in Sicily take place in several ways. To the east, normal subduction of oceanic crust (underlying the Ionian Sea) occurs underneath the Calabrian arc, whereas to the west, continental collision between the Pelagian block and the Calabrian arc (which extends from Calabria to the northeastern tip of Sicily and offshore of the island to the north) gives rise to the Maghrebian thrust belt on mainland Sicily. This belt consists mostly of stacked basinal and platform carbonates of Mesozoic-early Tertiary age deposited along the Africa passive margin. No clear subduction characterizes the area north of the HybleandashMalta plateau where it collides with the Maghrebian chain. The origin of the HybleandashMalta plateau is unclear. Geophysical data indicate, however, that its crustal structure is different from that of the surrounding Pelagian foreland. Crustal structure variations at the edge of the subducted African plate may thus cause the observed segmentation of the collisional arc system. A computer model of the region was created to learn about the deformation and faulting processes in the region. The simulation starts prior to the collision of the Pelagian block with the Calabrian arc. With time the HybleandashMalta plateau collides with the northern crustal block and, as a result, a new simulated topography, a new distribution of velocities and, most important, a new distribution of fracture zones are created. A shear fracture zone is formed east of the HybleandashMalta plateau (Malta escarpment) extending to the subduction zone at the Calabrian arc. A less active strike-slip fracture zone is created west of the HybleandashMalta plateau. An additional E-W trending active fracture zone is creating in the southern part of the simulated area. This feature may correspond to a fault zone which runs from the Strait of Sicily to the Ionian Sea.