The structure of the Calabro-Sicilian Arc: result of a post-orogenic intra-plate deformation

Abstract

Summary Morphotectonic and geological data show that this arc constitutes a post-orogenic ring-like system concentric round the Marsili ‘backarc’ basin. Peripheral concentric features comprise the ‘Aeolian andesitic ring’ and the arcuate troughs and ridges characteristic of the ‘forearc’ region. The Hyblean horst-like plateau and the Strait of Sicily represent the block-faulted foreland of the Sicilian segment of the Calabro-Sicilian Arc. The present shape of the arc has largely resulted from Plio-Quaternary vertical tectonic movements, superimposed on compressive structures caused by previous phases of tectonic deformation. The effect can be visualized as an outward-moving topographic wave producing inversion of tilting movements. This kinematic process (termed ‘krikogenesis’) is postulated as being related to midplate domal upwarp, dilatation and cauldron-like collapse of the Marsili block in the core of the arcuate system. Volcanicity appears to be associated with various stages of this geological history. Rather than originating by collision of two rigid plates, present-day morphological, volcanic and seismic configurations seem to be due to interaction of intra-plate ‘arches’, activated by local mantle movements.