Basin formation and inversion tectonics on top of the Egadi foreland thrust belt (NW Strait of Sicily)

Abstract

Extensional basins are known to occur on top of the Apennine Maghrebian fold-and-thrust belt that runs along Sicily and peninsular Italy. They formed mainly during the Plio-Quaternary, presumably in relation to the opening of the Tyrrhenian back-arc basin, while contraction was active at the thrust front. Contractional structures are often present within their sedimentary infill. One of these basins, INVO-2 located southwest of the Egadi islands, has been investigated using a closely spaced grid of multichannel seismic reflection profiles in order to define its structural style. Basin INVO-2 was formed along a system of NW-SE-trending extensional faults and is subdivided into two subbasins separated by a morphologic high. Flipping of half-graben polarity is often encountered along the axis of the two subbasins. Contractional structures, trending both perpendicular and parallel to the basin axis, occur within the basin infill, and in some instances these structures can be related to reactivation of previous extensional faults. Although the lack of well control does not allow a precise dating of the contractional episodes, they appear to occur intermittently, from the onset of the basin until recent times, intercalated to a dominant extensional regime. The origin of compressional pulses in this extensional setting can be looked for in the dynamics of the adjacent Maghrebian collision zone.