Uplift and contractional deformation along a segmented strike-slip fault system: the Gargano Promontory, southern Italy

Abstract

The Gargano Promontory in southern Italy is a region of localized uplift and contractional deformation within the Apulian foreland province. Our field mapping has defined two main fault systems that controlled the uplift of the Gargano block. E–W-trending strike-slip faults bound the northern and southern margins of the uplifted block, defining a compressive stepover zone between the two fault zones. The second system strikes NW–SE with primarily reverse to oblique-reverse displacements. Uplift was accommodated by a broad antiformal fold and reverse motion on the NW–SE fault system. This deformation is attributed to localized high compressive stress within the stepover region, driven by slip on the bounding strike-slip faults. Three-dimensional numerical models incorporating the observed fault geometries and slip sense support our interpretation. Results show that significantly higher compressive stresses occur within the fault overstep region, and computed stress trajectories agree closely with the orientations of contractional features observed in the field. Although the role of strike-slip faulting in the deformation of the Gargano Promontory has been proposed previously, this mechanism provides a new model for the localized uplift and related deformation. We also cite similar occurrences of this mechanism in the complexly deformed interior of the Apennine fold–thrust belt.