Geological and geophysical evidences for mud diapirism in south-eastern Sicily (Italy) and geodynamic implications

A recent investigation on the northern margin of the Hyblean Plateau in south-eastern Sicily highlights the occurrence of a clayey diapiric intrusion into the foreland carbonate series. The piercing body, exposed along a ∼270 long and ∼30 m deep NE-SW elongated quarry, consists of serpentinite-bearing clayey material. As suggested by the internal contractional features and by its geometric relations with the adjacent rocks, the clayey body intruded in the foreland series producing on its flanks a set of domino-arranged normal faults which nucleated as a result of gravitative collapse. Taking into account previous petrological studies, which provided information about the origin of the mud, a deep geodynamic model for the northern part of the Hyblean Plateau is here presented. The mud diapirs originated from the uprising of pre-existing serpentinite bodies and others products of alteration probably developed along an ancient ridge-transform intersection where a hydrothermally altered mantle wedge occurred. This interpretation is supported by seismic, magnetic and gravimetric anomalies beneath the analyzed area and has implications on its geodynamic evolution.