STRUCTURAL AND TIME CONSTRAINTS OF LONG-LIVED, CRUSTAL-SCALE STRUCTURES IN THE FORELAND DOMAINS OF THE APENNINE-MAGHREBIAN CHAIN (SOUTHERN ITALY): IMPLICATIONS FOR BACKGROUND DEFORMATION

In southern Italy, oil and thermogenic gas accumulated in Mesozoic carbonate rocks belonging to the Apulian platform. At this location, petroleum plays are related to the main phases of Tethyan crustal stretching. These carbonate reservoir rocks crop out in the Puglia Region (Gargano Promontory, Murge Plateau) and in SE Sicily (Hyblean Plateau); they are crosscut by 2 regional structures: The Mattinata (MFZ) and The Scicli-Ragusa (SRFZ) Fault Zones respectively. Both are crustal-scale fault zones characterized by predominant strike-slip motion, they recorded different tectonic phases and played a important role in the structural arrangement of the foreland domains of the Apennine-Maghrebian Chain. Thus they are key areas in order to gather a new knowledge on the fracturing state of the Mesozoic carbonate reservoirs. In this work, we focus on the kinematic and evolutionary histories of these fault zones by mean of detailed geological, structural and morphological analyses. The MFZ is a E-W oriented structure and crosscuts the Gargano Promontory that is part of an about 3km-thick Jurassic–Cretaceous carbonate succession consisting, of shallow-water carbonates passing into slope and basinal deposits. In agreement with other authors, our data suggest two kinematic episodes associated to the MFZ: 1sta left-lateral motion (L. Mioc.–E. Pleist.), then a rightlateral motion (since Middle-Late Pleist. up to present). The SRFZ is NNE-SSW oriented structure which crosscuts the Hyblean Plateau. This Plateau is made up by Mesozoic-to-Tertiary carbonate rocks belonging to platform-to-ramp environments. Our data are consistent with the SRFZ being developed as a dextral strike-slip fault, since Up. Mioc.. Then, some SRFZ-related fault segments have been reactivated since the L. Pleistocene with a left-lateral kinematics. According to the our results, both fault zones nucleated and developed, since Late Mioc., under a stress field characterized by horizontal NE–oriented and NW-oriented σ1 and σ3 axes, respectively. A second kinematic episode, associated to the two FZ, started in the Middle-Late Pleistocene, driven by a new stress field with horizontal σ1 and σ3 axes oriented NW–SE and NE–SW, respectively. Our results suggest that the foreland domains of the Apennine-Maghrebian Chain were subjected to two different stress fields that, away from the main fault zones, were responsible of a background deformation which strongly affects the fluid flow properties of the carbonates.