Understanding progressive‐arc‐ and strike‐slip‐related rotations in curve‐shaped orogenic belts: The case of the Olevano‐Antrodoco‐Sibillini thrust (Northern Apennines, Italy)

Abstract

We report on a paleomagnetic study of the southern sector of the Olevano‐Antrodoco‐Sibillini (OAS) thrust front, which corresponds to the southern limb of the Northern Apennines (Italy) orogenic salient. A lively debate has developed regarding the oroclinal/progressive‐arc versus non‐rotational nature of the OAS, which has been alternatively interpreted as a dextral strike‐slip fault, dextral transpressive fault, or frontal to oblique ramp that reactivated pre‐existing Jurassic normal faults. Here, we document the paleomagnetism, integrated with biostratigraphic and structural data, of 52 new sites from both the OAS hanging wall and footwall. On the basis of 39 retained sites, we find a peculiar pattern of tectonic rotations along the OAS thrust that evidences four rotational domains. The thrust footwall is characterized by a southern domain that undergoes an approximately 30° counterclockwise rotation with respect to the stable foreland, and an approximately non‐rotated domain. The data from the hanging wall indicate the occurrence of a dextral strike‐slip component along the southern sector of the OAS thrust supported by a strong clockwise rotation close to the NE‐SW lateral ramp, which rapidly fades 1 km from the thrust front. A slight but significant CW rotation observed in the remaining sites from the hanging wall confirms the progressive nature of the OAS, and its structural position as the southern limb of the Northern Apennines salient. Our detailed paleomagnetic study is crucial in discriminating between progressive‐arc‐ and strike‐slip‐related components in the main curved orogenic front of the Northern Apennines.

Tectonic control on the petrophysical properties of foredeep sandstone in the Central Apennines, Italy

“…First, we calculated σ 3 and σ 1. Our field data and previously published data [ Coli , ; Cavinato et al ., ; Calamita and Deiana , ; Calamita et al ., ; Corrado , ; Turtù et al ., ] indicated a compressional regime during the slip of the Olevano–Antrodoco thrust fault. This implies a horizontal σ 1 oriented SW‐NE and a vertical σ 3.…”

“…The Olevano–Antrodoco is an out‐of‐sequence thrust fault [ Cipollari et al ., ] characterized by multiphase prevalently dextral transpressional kinematics [ Coli , ; Cavinato et al ., ; Calamita and Deiana , ; Calamita et al ., ; Corrado , ; Turtù et al ., ], although evidence for strike‐slip kinematics on other fault segments oriented N‐S in Central Apennines are reported by some authors [ Castellarin et al ., ; Cello et al ., ; Cello and Mazzoli , ].…”

Magmatism, mantle evolution and geodynamics at the converging plate margins of Italy

“…These include the so-called 41° Parallel Line, which divides the northern and southern Tyrrhenian Sea basins, the Tindari-Letojanni fault systems and others (e.g. Serri 1990;Bruno et al 2000;Rosenbaum et al 2008;Turtù et al 2013). It has been suggested that tear-off fractures of the Adriatic-Ionian subducted slab occur along some of these faults.…”

Behaviour of minor arcuate shapes hosted in curved fold-and-thrust belts: an example from the Northern Apennines (Italy)

“…Studies from arcs of 10-100 km of amplitude have documented different behaviours: there are minor arcs characterized by CCW and CW rotations along the limbs (Gran Sasso Range (Satolli et al 2005)), block rotations due to strike-slip faults (e.g. Central Apennines (Mattei et al 1995) and Olevano-Antrodoco sibilini thrust (Turtù et al 2013)) and small homogeneous CW-rotated structures (e.g. Mount Maiella (Jackson, 1990) and Mount Greco -Mount Genzana (Marton & D'Andrea, 1992)).…”

“…In particular, the development of the Northern Apennines progressive arc was influenced by the architecture of the Adria palaeomargin (Calamita et al 2012). The system has a component of primary and progressive arc development: its primary curvature was accentuated during orogenesis by CCW and CW tectonic rotations in its northern and southern limbs, respectively Turtù et al 2013). The importance of inversion tectonics has also been shown through palaeomagnetism in minor arcs, as in the case of the Gran Sasso range (central Apennines), where the Adria palaeomargin played the role of an indenter causing strong rotations in its apex (Satolli et al 2005).…”