Internal structure and tectonic evolution of an underthrust tectonic mélange: the Sestola-Vidiciatico tectonic unit of the Northern Apennines, Italy

Abstract

The Sestola-Vidiciatico Tectonic Unit (SVTU) in the Northern Apennines is an underthrust tectonic melange presently sandwiched between the Tuscan-Umbrian foredeep units and the overlying Ligurian/Subligurian thrust-nappe. The SVTU has been generated during the collision between the European and the Adria plates and now it separates the former oceanic accretionary wedge -Ligurian/Subligurian thrust nappe-from the underlying fold-and-thrust belt formed by Adria sedimentary units. The collision caused an eastward migrating foredeep basin and the overthrusting of the frontal part of the Ligurian/Subligurian thrust-nappe on the subducting Adria margin. Part of the inner lower-slope sediments of the migrating foredeep basin have been unconformably deposited on a frontal prism formed by material already accreted in the Ligurian/Subligurian prism gravitationally and tectonically reworked. The frontal prism and its sedimentary cover have been progressively dragged down along the plate boundary zone generating the SVTU. The lower-slope sediments have been incorporated in the melange as they were not completely lithified, and they show a long deformation history ranging from continuous and pervasive soft-sediment deformation to discontinuous brittle deformation concentrated along faults and mainly controlled by cycles of fluid pressure as testified by the presence of crack-and-seal texture and implosion breccia in the veins

Early exhumation of underthrust units near the toe of an ancient erosive subduction zone: A case study from the Northern Apennines of Italy

“…2) (Bettelli et al, 2002a(Bettelli et al, , 2002bCerrina Feroni et al, 2002a;Plesi, 2002;Remitti et al, 2007Remitti et al, , 2011. This material was deposited on the frontal part of the LigurianSubligurian oceanic prism starting from the middle Eocene .…”

“…2). During the overriding on the subducting Adria plate, the upper plate was not involved in major tectonic structures as indicated by the mildly deformed Epiligurian Succession, i.e., the forearc slope sediment (Vannucchi et al, 2008;Remitti et al, 2012).The different blocks forming the Northern Apennine interplate shear zone mélange are made of (Remitti et al, 2007(Remitti et al, , 2011Vannucchi et al, 2008Vannucchi et al, , 2012:…”

“…In the southeastern part of the Emilia Apennines, this plate boundary shear zone crops out as a regional block-on-block tectonic mélange called the Sestola-Vidiciatico tectonic unit (Remitti et al, 2007Vannucchi et al, 2008), whereas in the northwestern part of the Emilia Apennines, it crops out as a more coherent unit, known as the Subligurian Units (Figs. 1 and 2).…”

“…In any case, the age of the youngest block present in the tectonic mélange gives a lower limit to the time of its incorporation in the plate boundary shear zone (Remitti et al, 2007(Remitti et al, , 2011, and references therein) (Fig. 2).…”

Landslide inventory updating by means of Persistent Scatterer Interferometry (PSI): the Setta basin (Italy) case study

“…The Ligurian units tectonically overlie the Cervarola-Falterona unit that represents the detached top of the Tuscan succession; Cervarola-Falterona sequence is made of Lower Miocene deep-sea silicoclastic sediments that accumulated in the eastward migrating foredeep basin developing in front of the Appenninc orogenic wedge (Remitti et al 2007). …”