On the tectonic evolution of the Ligurian accretionary complex in southern Italy

Abstract

Unraveling the deformation pattern characterizing the transition from the final oceanic subduction stages to the early stages of deformation of the foreland continental margin is crucial for a better understanding of geodynamic processes taking place at convergent plate boundaries. In particular, the combined role of internal wedge dynamics and continental margin architecture in controlling the tectonic evolution of an accretionary complex during its final emplacement onto the foreland continent is discussed in this study. To this purpose, integrated structural, stratigraphic and low-T thermochronometric analyses have been performed on the Ligurian accretionary complex units exposed in the Campania region (Italy) and on continental margin successions located in their footwall, as well as on related foredeep and wedge-top basin deposits. Our results point out a series of late Early Miocene (Burdigalian) shortening events, also involving buttressing of the accretionary wedge against the crustal ramp of the foreland continental margin. Emplacement of the overthickened accretionary complex onto the distal part of the continental margin was followed by horizontal extension and wedge thinning, aiding the development of wedge-top depocenters. Extension may be either related with reduced subduction rates during the Middle Miocene, or with a period of subduction erosion (known to have occurred in the northern Apennines in the same time frame). Early Miocene NW-SE shortening recorded by Ligurian accretionary complex units is completely unrelated with later (Late Miocene to Pleistocene) NE-directed thrusting in the Apennines, which was coeval with back-arc extension in the Tyrrhenian Sea. Therefore, our results emphasize the occurrence of a major discontinuity in the Neogene geodynamic evolution of the southern Apennines, whose tectonic history may be clearly subdivided, from a kinematic point of view, into pre- and syn-Tyrrhenian back-arc extension stages

The Culmination of an Oblique Time‐Transgressive Arc Continent Collision: The Pollino Massif Between Calabria and the Southern Apennines, Italy

“…Prominently absent from the wedge are the original basement roots, from which the units have been thrust‐detached and transported. With reference to this transport direction, they are grouped into internal units of the Tethys domain consisting of both oceanic rocks (Liguride Complex; Ogniben, ; Liberi et al, ; Liberi & Piluso, ), some with high‐pressure metamorphism (e.g., Frido Unit; Vezzani, ; Amodio‐Morelli et al, ; Vitale et al, ) and nonmetamorphic basinal and continental deposits synchronous with the later development of the Apennine thrust wedge (Nord‐Calabrese and Sicilide Units; Bonardi et al, , ; Ciarcia et al, ; Knott, ; Ogniben, ; Vitale & Ciarcia, ). In contrast, the external units consist of carbonate platform sequences partly from the Apulian margin (Bonardi et al, ; Vitale & Ciarcia, ).…”

Petrogenesis and deformation history of the lawsonite‐bearing blueschist facies metabasalts of the Diamante‐Terranova oceanic unit (southern Italy)

“…Several thrust sheets made up of (1) metamorphic ophiolite sequences (Diamante‐Terranova, Malvito, Gimigliano and Frido units; Amodio‐Morelli et al., ; Cello, Invernizzi, & Mazzoli, ; Liberi, Morten, & Piluso, ; Liberi & Piluso, ; Rossetti, Goffé, Monié, Faccenna, & Vignaroli, ; Spadea, ) and (2) sedimentary deep‐basin successions (Ligurian Accretionary Complex; Ciarcia, Mazzoli, Vitale, & Zattin, ; Vitale, Ciarcia, & Tramparulo, ) are exposed in the northern Calabria and Basilicata regions (Figure a). These tectonic units are interpreted as remnants of (1) buried and subsequently exhumed oceanic slivers and (2) an accretionary wedge, respectively, formed following the subduction of Neotethys oceanic lithosphere.…”

Structural, stratigraphic, and petrological clues for a Cretaceous–Paleogene abortive rift in the southern Adria domain (southern Apennines, Italy)

“…The southern Apennine belt (Figure a) is made of several thrust sheets unconformably covered by Mio‐Pliocene sediments deposited in wedge top and extensional basins (e.g., Bonardi et al, ; Ciarcia & Vitale, ; Mazzoli et al, ; Mazzoli et al, ; Menardi Noguera & Rea, ; Patacca & Scandone, ; Scrocca, ; Vitale et al, ). Units made of deep‐sea basin successions (Ligurian Accretionary Complex; Ciarcia, Mazzoli, Vitale, & Zattin, ; Vitale, Fedele, et al, ) are located at the top of the tectonic pile and cover a thrust wedge consisting of several stacked tectonic units made of Meso‐Cenozoic sedimentary successions, mostly detached from their Paleozoic basement (i.e., the subducted Adria Plate). This thrust wedge includes, from the top to the bottom, (a) slope to platform carbonate units derived from the Apennine platform (Apennine platform units in Figure b; Mostardini & Merlini, ); (b) imbricated slices of the Lagonegro–Molise Basin successions (Lagonegro–Sannio and Fortone units in Figure b; Patacca, ); and (c) para‐autochthon buried Apulian carbonate units (inner buried Apulian platform in Figure ; e.g., Scrocca, Carminati, & Doglioni, ).…”

“…The southern Apennine belt ( Figure 1a) is made of several thrust sheets unconformably covered by Mio-Pliocene sediments deposited in wedge top and extensional basins (e.g., Bonardi et al, 2009;Mazzoli et al, 2008;Mazzoli et al, 2014;Menardi Noguera & Rea, 2000;Patacca & Scandone, 2007;Scrocca, 2010;Vitale et al, 2017). Units made of deep-sea basin successions (Ligurian Accretionary Complex; Ciarcia, Mazzoli, Vitale, & Zattin, 2012;Vitale, Fedele, et al, 2013) Figure 1; e.g., Scrocca, Carminati, & Doglioni, 2005). The foreland is represented by the rocks exposed in the Apulian and Adriatic Sea regions (Figure 1a; e.g., Ricchetti, Ciaranfi, Luperto Sinni, Mongelli, & Pieri, 1988).…”