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

Abstract

The Pollino Massif is the most southeastern outcrop of the Apennine core. It marks the transition between Apenninic shortening and extension, respectively, SE and NW of the massif and is also the cusp of a southeastward plunge that characterizes the submerged Apennines. The SE limit of NE‐SW extension merges with the east limit of Tyrrhenian extension in Calabria. This strategic position is expected to transition southeastward in the progressive oblique collision of the Calabrian forearc and Apulia. We test this hypothesis using published results and new field data. The time‐transgressive emergence of basins on the Apennine thrust wedge is quantitatively consistent with the ESE rollback of the Calabrian arc. Specifically, a thrust‐normal slip reversal on a SW dipping fault is responsible for the tectonic collapse that lead to the Mercure Basin along strike NW of the Pollino Massif and to an east‐to‐west reversal of drainage. This reversal is timed by an intermediate stage of trapped internal drainage with Mid‐Pleistocene lacustrine sedimentation, but it may young to SE as the normal displacement on the border fault decreases gradually to SE and vanishes near the apex of the massif. On the SE side of the massif, contractional tectonics persists at least into the Mid‐Pleistocene and likely later, while NE‐SW extension is absent. Prominent normal faults in that area accommodate range‐parallel extension and are coupled with the thrust faults. The combination of longitudinal extension with a counterclockwise rotation of hanging‐wall units and thrust directivity can account for the final setting in the Apennines.

Crustal Structure of the Seismogenic Volume of the 2010–2014 Pollino (Italy) Seismic Sequence From 3D P- and S-Wave Tomographic Images

“…From the geological point of view, this result is not surprising, relying on the fact that Southern Italy is floored by the fold and thrust belt in the western and central part (Ferranti et al, 2017). More specifically, regarding the Pollino area, it has been found that during the late contraction stage (Late Pliocene to Early Pleistocene), the thick Apulia crust was involved in the thrust system and then reversely reactivated as normal faults in the actual extensional regime, responsible for the seismic hazard of the area (Ferranti et al, 2017;Filice and Seeber, 2019). For the first time, a three-dimensional tomographic image shows with impressive detail what until now had been hypothesized by geological sections.…”

Fault‐controlled base‐of‐scarp deposits

“…The Crati Basin hosts well‐known examples of fault‐controlled shoal‐water and Gilbert‐type deltas (Colella, 1988b), and in the present study we focus on facies variations and vertical evolution of the lower portion of the Early‐Middle Pleistocene Civita section (Figure 4a). The Civita section developed in the northern sector of the Crati Basin along a fault‐segment of the 15‐km long Pollino Fault (Colella, 1988a,b; Filice and Seeber, 2019), and pertain to the Pleistocene Synthem (PlS) defined by Spina, Tondi, and Mazzoli (2011; Figure 4a). The Pollino Fault has an oblique normal‐sinistral kinematics (Chiarabba, Agostinetti, & Bianchi, 2016; Ghisetti & Vezzani, 1982; Monaco & Tansi, 1992; Tansi et al., 2007, 2016; Van Dijk et al., 2000) forming a SW facing fault scarp that favoured the formation of several vertically stacked Plio–Pleistocene deltaic units having a total thickness of ~300 m (Colella, 1988b; Figure 4a).…”

Ground-penetrating radar signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

“…This set of conjugate SW-and NEdipping normal faults represents the local expression of the Quaternary extensional belt that develops all along the Ital-ian peninsula, nearly parallel to the axial zone of the Apennines, from northern Tuscany to the Calabrian Arc (Brozzetti, 2011). North of Campotenese (Lucania and southern Campania), the Apennine extensional belt includes several continental basins and their boundary faults, such as the Irpinia, Vallo di Diano, Tanagro, Melandro-Pergola, and Val d'Agri (Ascione et al, 1992;Maschio et al, 2005;Amicucci et al, 2008;Villani and Pierdominici, 2010;Brozzetti, 2011;Filice and Seeber, 2019;Bello et al, 2021). To the south, it continues with the Crati graben that dissects the northern sector of the Calabrian Arc (Tortorici et al, 1995;Brozzetti et al, 2012Brozzetti et al, , 2017b.…”