Paleomagnetism of the Peloritan Terrane (NE Sicily): From Greater Iberia to the Neo Apennine-Maghrebide Arc

Abstract

Calabria and the Peloritan Mts. of NE Sicily are exotic terranes predominantly formed by Hercynian rocks interrupting the Meso-Cenozoic sediments exposed along Apennine-Maghrebide chains. Dual-polarity pre-tilting magnetization direction retrieved from 5 Jurassic, 5 upper Cretaceous-Eocene, and 4 upper Oligocene sedimentary sites from external-intermediate Peloritan nappes yield 99° ± 12°, 131° ± 15°, and 138° ± 12° (respectively) clockwise (CW) rotations with respect to Europe. Upper Cretaceous-Oligocene values are similar to the ∼130° CW late Miocene-Early Pleistocene rotation previously documented on internal Maghrebian nappes of W Sicily. Jurassic data imply a ∼30° Early Cretaceous counterclockwise (CCW) rotation, similar for sign, magnitude, and timing to Iberia rotation, proving that the Peloritan crust was part of Greater Iberia before its <30 Ma fragmentation and dispersal. Furthermore, 20 Jurassic-Oligocene sites yield post-tilting overprint direction (later rotated up to 60° CW) that was acquired synchronous to late Miocene-Pleistocene rotation. The Peloritan rotation is completely different from the 160° post-late Jurassic CCW rotation documented on NE Calabria, and demonstrates that the two terranes underwent independent drift histories. Lack of a Sardinian rotation fingerprint (90° CCW between 30 and 15 Ma) suggests that the Peloritan terrane lied S of the Calabria-Sardinia CCW rotating system, at the non-rotational apex of an Oligocene-early Miocene “Paleo Apennine-Maghrebide Arc.” The Peloritan terrane was stacked onto the African margin and incorporated in the Maghrebian chain in mid Burdigalian (18–17 Ma). Afterward, it formed the S limb of the “Neo Apennine-Maghrebide Arc,” and was passively carried on top of CW rotating Maghrebide nappes during late Miocene-Early Pleistocene (12–1 Ma).

Key Points

• The Peloritan terrane rotated 30° CCW during Early Cretaceous (similar to Iberia), and 130° CW since the late Miocene on top of Maghrebides

• Paleomagnetism proves that Iberia, S Sardinia and AlKaPeCa blocks formed “Greater Iberia” before Oligo-Miocene (<30 Ma) dispersal

• Paleomagnetic data indicate that after 30 Ma the Peloritan and Calabria terranes underwent different drift and rotation histories

1 Introduction

The backbone of Calabria (southern Italy) and Peloritan Mts. of NE Sicily is made of Hercynian metamorphic and intrusive rocks that strikingly interrupt the geological continuity of the Apennines and the Maghrebides of Sicily, made of Meso-Cenozoic sediments piled up during Alpine-Apennine tectonics (Figure 1). Traditionally, the “Calabro-Peloritan block” has been considered a unique semi-rigid terrane of European affinity recording a long history of Hercynian tectonics and metamorphism, Early Jurassic rifting during Alpine Tethys spreading, Eo-Oligocene incorporation into the Alpine chain and metamorphic overprint, and final early Miocene-to-present stacking over the Africa-Adria margins (Aldega et al., 2011; Alvarez et al., 1974; Amodio-Morelli et al., 1976; Bonardi et al., 2001; Bouillin et al., 1987; Cifelli et al., 2007; Cirrincione et al., 2012, 2015; Faccenna et al., 1997, 2001; Malinverno & Ryan, 1986; Mattei et al., 2002; Passeri et al., 2014; Rossetti et al., 2001, 2004; Santantonio et al., 2016; Vignaroli et al., 2012). Further W, the Greater and Lesser Kabylies and the Alboran domain share similar geologic characteristics with the Calabro-Peloritan terrane, and tectonically overlie Meso-Cenozoic sediments of the Algero-Moroccan Maghrebides (Tell and Rif), and Betic chains (Figure 1).

Figure 1

Geographic frame and main tectonic features of the central-western Mediterranean. The AlKaPeCa terranes, indicated in red, are dispersed and stacked above the circum-Mediterranean mountain ranges. South Sardinia (SS) and North Sardinia (NS) are separated by the Nuoro fault system. Black box indicates location of Figure 3.

Overall, they are referred as to AlKaPeCa, a series of terranes that—after the pioneer work by Alvarez et al. (1974)—are inferred to have been located adjacent to the Iberian-Provencal margin of Europe until Early Oligocene. After ∼30 Ma, the AlKaPeCa blocks—already incorporated in the Alpine chain—were fragmented and progressively dispersed, and drifted hundreds of km ESE-ward (Calabro-Peloritan terrane) SSE-ward (Kabylies) and SW-ward (Alboran) on top of nappe piles that followed the roll-back of isolated Alpine and Neo-Tethys oceanic slab fragments (Alvarez et al., 1974; Malinverno & Ryan, 1986; Patacca et al., 1990). The most solid proxies for AlKaPeCa drift magnitudes and ages are the width and spreading ages of back-arc basins opening at the rear of the migrating orogenic wedges. A first ∼400 km SE-ward drift of the Calabro-Peloritan block, along with the Corsica-Sardinia microplate, is testified by Oligo-Miocene (30-15 Ma) rifting and oceanic spreading of the Liguro-Provencal Basin (Burrus, 1984; Jolivet et al., 2020; Séranne, 1999). After a ∼5 Ma quiescence, the Calabro-Peloritan block separated from Sardinia and further drifted some 500 km ESE-ward, synchronous with spreading of the southern Tyrrhenian Sea from 10 to 2 Ma (Kastens et al., 1988; Mattei et al., 2002; Nicolosi et al., 2006; Patacca et al., 1990). Beside these, no other kinds of geologic/geophysical data from Corsica-Sardinia microplate or AlKaPeCa terranes constraining their drift magnitudes exist. On the other hand, drift timing may be properly documented by paleomagnetic vertical-axis rotations obtained from different age rocks, and such data usefully complement ages derived from back-arc basins. Microplate/terrane drift magnitudes can be also inferred by hypothesizing the location of a paleomagnetic rotation pole that best matches the overall geological evidence.

A wealth of paleomagnetic data gathered since the 1980s from Sardinian volcanic and sedimentary rocks robustly documented that the early-mid Miocene (21–15 Ma) SE-ward drift of the Corsica-Sardinia microplate was accompanied by a ∼60° counterclockwise (CCW) rotation (Gattacceca et al., 2007; Montigny et al., 1981; Speranza et al., 2002). Differently than Corsica-Sardinia, the AlKaPeCa terranes are mainly formed by Hercynian metamorphic and intrusive rocks unfit to paleomagnetic investigations, thus virtually lack data useful for terrane dispersal reconstructions. Thus, few paleomagnetic data sets from the AlKaPeCa terranes are available in the literature.

For instance, no paleomagnetic data are available from the Kabylies whereas in the Alboran terrane, data from the Mesozoic calcareous sequences from both the Betics (Spain) and the Dorsale Calcaire (Morocco) suggest differential rotations, partially related to outwardly directed Late Oligocene thrusting around the Gibraltar arc (Platzman, 1992; Platzman et al., 1993, 2000). Available data show a great scatter, and the overall Mesozoic-early Cenozoic rotation and drift of the Alboran terrane remain virtually unresolved.

In the Calabrian terrane the upper Miocene-Pleistocene post-orogenic terrigenous blanket has been extensively investigated, and yielded a 20° clockwise (CW) rotation occurring between 2 and 1 Ma (e.g., Cifelli et al., 2007 and references therein). Apart from preliminary data by Manzoni (1979) and Manzoni and Vigliotti (1983), the unique pre-late Miocene paleomagnetic data gathered so far on the Calabrian terrane come from Mesozoic sedimentary patches (Longobucco sequence in NE Calabria) lying above the Hercynian basement (Siravo et al., 2022). Such data documented a 160° post-late Jurassic CCW rotation with respect to Europe that the authors related to the sum of an early Miocene rotation along with Sardinia, plus local block rotation due to Early Cretaceous left-lateral shear along Alpine Tethys. However recent results from southern Sardinia by Siravo et al. (2023) indicate that part of this huge Calabria rotation could be related to the Early Cretaceous Iberia rotation, as illustrated below.

Another unsolved issue concerns Iberia, its CCW rotation magnitude and age, and the putative effects on AlKaPeCa blocks. After several decades of investigations and debate, a consensus has developed on an Early Cretaceous (150–120 Ma) ∼30° CCW rotation of Iberia (Van der Voo, 1969) during Bay of Biscay opening, though the event duration (Gong et al., 2008; Neres et al., 2012, 2013) and the rotation process remain controversial. Some scientists inferred an Iberia rotation pole located on N Europe (Figure 2a), implying sinistral shear along the Pyrenees, ESE-ward Iberia drift along with Corsica-Sardinia, AlKaPeCa blocks, and Brianconnais domain, and Valais ocean spreading (Asti et al., 2022; Barnett-Moore et al., 2016, 2017; Handy et al., 2010; Le Breton et al., 2021; Stampfli & Borel, 2002). Others—conversely—argued for a rotation pole adjacent to Iberia itself (Figure 2b), implying a contemporaneous opening of the Bay of Biscay, subduction/shortening onset along the Pyrenees, and decoupling from Corsica-Sardinia and Peloritan-Calabrian terranes blocks along a major dextral shear zone located SE of Iberia (Advokaat et al., 2014; van Hinsbergen et al., 2017; Vissers & Meijer, 2012). Finally, an extensional Iberia-Europe boundary was proposed by Tavani et al. (2018), implying a rotation pole located E of Iberia.

Figure 2

Opposite paleogeographic/evolutionary models of Iberia and AlKaPeCa terranes in the Early Cretaceous. Paleogeography snapshot is relative to 145 Ma (Jurassic-Cretaceous boundary, before Bay of Biscay opening and Iberia rotation). Dashed tectonic boundaries are relative to the future Iberia rotation/drift, bracketed in the 150-120 Ma age window (Neres et al., 2012, 2013). (a) Left-lateral strike-slip boundary between Iberia and Europe; following paleomagnetic data and interpretations by Siravo et al. (2022, 2023) (withe diamonds) and data presented in this study (red diamond) South Sardinia, Calabria, Peloritan, Balearics, Kabylies, and Iberia microplates/terranes were fragments of “Grater Iberia.” (b) Scissor-like model by Advokaat et al. (2014), implying contemporaneous extension in the Bay of Biscay and shortening along the Iberia-Europe boundary (future Pyrenees). Corsica, Sardinia, Calabria and the Peloritan terranes are considered as part of Europe.

The first hypothesis was recently (at least in part) supported by Siravo et al. (2023), who showed that S Sardinia underwent an excess post-Jurassic CCW rotation with respect to N Sardinia-Corsica, these latter forming a single microplate (Vigliotti et al., 1990). The observed excess of CCW rotation is explained assuming that a S Sardinia block participated to the 150–120 Ma Iberia rotation (Figure 2a). Siravo et al. (2023) hence suggested that S Sardinia, Balearic Islands, Calabria, Peloritan, Kabylies, and Alboran were fragments of “Greater Iberia,” joined to Iberia before the 30 Ma Liguro-Provencal rifting onset. However, no data have been provided so far from the AlKaPeCa blocks—else than Calabria—to verify the occurrence of the Iberian Early Cretaceous CCW rotation fingerprint.

Here we report on the paleomagnetism of 55 upper Triassic to upper Oligocene sites from the sedimentary cover of the external and intermediate Peloritan nappes. Although most of the sites underwent a post-mid Burdigalian magnetic overprint, 14 sites (114 oriented cores) escaped remagnetization, and testify a rotation pattern completely different from that observed in NE Calabria. Data prove for the first time that at least one of the AlKaPeCa blocks was effectively a piece of Greater Iberia, and that after its 18-17 Ma stacking over the African crust, the Peloritan block was passively carried on top of internal Maghrebide nappes that underwent thrust tectonics and synchronous 130° CW rotation since the late Miocene. These data also highlight the distinct rotation patterns and kinematics of two different “Paleo” (Oligocene-early Miocene) and “Neo” (late Miocene-Pleistocene) Apennine-Maghrebide orogenic Arcs.

2 Oligo-Pleistocene Paleomagnetic Rotations Around the Liguro-Provencal and Tyrrhenian Back-Arc Basins

Since Early Oligocene (30 Ma), the roll-back of oceanic Alpine and Neo-Tethys slab fragments has completely deformed the geometry of a former rectilinear NE-striking W Mediterranean Alpine chain, and the European, African and Adriatic margins (Alvarez et al., 1974; Carminati et al., 2012; Doglioni et al., 1997; Faccenna et al., 2001; Malinverno & Ryan, 1986). SE-ward progressive retreat of these slabs induced the drift-rotation of the Corsica-Sardinia microplate and the adjacent orogenic wedge (AlKaPeCa terranes, Alps, and the more external Apennines and Maghrebides), and the formation of volcanic arcs, significantly active in Sardinia from 32 to 12 Ma and in peri-Tyrrhenian margins since 11 Ma to present-day (Lustrino et al., 2009). At the rear of the migrating system, diachronous spreading of the Liguro-Provencal and Tyrrhenian back-arc basins occurred (Figure 1).

Rifting of the Liguro-Provencal Basin started during Early Oligocene (30 Ma), whereas a breakup unconformity in the Provencal margin suggests that oceanic spreading occurred at 21 Ma (Séranne, 1999). The end of spreading is placed at 15 Ma by paleomagnetic data from Sardinia (Gattacceca et al., 2007; Speranza et al., 2002), as the interpretation of the magnetic anomaly pattern from the Liguro-Provencal Basin is controversial (Bayer et al., 1973; Schettino & Turco, 2006). Back-arc spreading ceased for some 5 Ma, and jumped eastward from the Liguro-Provencal to the Tyrrhenian Sea, leaving on its way the Corsica-Sardinia microplate.

Rifting onset in the Tyrrhenian Sea is placed at 10–8 Ma (Tortonian) by ODP data (Kastens et al., 1988; Patacca et al., 1990), or at 12 Ma (late Serravallian) by geologic-paleomagnetic data from the post-orogenic sedimentary blanket of Calabria (Mattei et al., 2002). Oceanic breakup in the southern Tyrrhenian Sea formed two deep oceanic crust basins encircling basaltic seamounts called Vavilov (5–3 Ma) and Marsili (∼2 Ma, Kastens et al., 1987; Nicolosi et al., 2006).

Paleomagnetic data from Corsica-Sardinia, the southern Apennines, and the Maghrebides of western Sicily yielded vertical-axis rotations whose timing and magnitude significantly helped to better constrain the kinematics and timing of the retreating subduction system since 30 Ma. Recent Eocene paleomagnetic results from SW Sardinia along with a re-evaluation of the Corsica-Sardinian data set (Siravo et al., 2023) suggested that S Sardinia rotated 30° CCW during the 30–21 Ma rifting of the Liguro-Provencal basin, prior to the well acknowledged 60° CCW rotation of the whole Corsica-Sardinia microplate during the 21–15 Ma Liguro-Provencal Sea spreading. During Oligocene-early Miocene, the Alpine-Apennine belt lying ahead of Corsica-Sardinia must have undergone a similar amount of CCW rotation that was effectively documented in Eocene sediments from Tuscany (Caricchi et al., 2014) and Jurassic Ammonitico Rosso from NE Calabria (Siravo et al., 2022). Afterward, from 10 to 1 Ma, a further ESE drift of the Calabro-Peloritan terrane occurred following the roll-back of the Ionian oceanic slab—considered a fragment of the Permo-Triassic Neo-Tethys (Speranza et al., 2012; Stampfli & Borel, 2002)—still yielding deep seismicity below the southern Tyrrhenian Sea down to 500 km depths (Chiarabba et al., 2008; Lucente et al., 1999). The triangular-shape southern Tyrrhenian Sea formed as a back-arc basin at the rear of the migrating-bending orogenic wedge (Figure 1).

Late Miocene (Serravallian)-Pleistocene data from Calabria solidly show that the post-10 Ma ESE-ward drift of the Calabria terrane was virtually non-rotational, apart from a 20° CW rotation occurring between 2 and 1 Ma (Cifelli et al., 2007 and references therein). The Calabro-Peloritan block drift caused a “saloon-door” deformation in the southern Apennines and Sicilian Maghrebides, where opposite-sign rotations were measured (Speranza et al., 2003). The regional-scale CCW rotation of the southern Apennines is constrained at 80° (Gattacceca & Speranza, 2002), although a 130° rotation was measured locally (Maffione et al., 2013). The south Apennine CCW rotation mostly occurred during late Miocene, as Plio-Pleistocene rotation values do not exceed 20° (Mattei et al., 2004; Sagnotti, 1992; Scheepers & Langereis, 1994). An almost specular and synchronous rotation pattern occurred in the Maghrebian chain of Sicily, where 130° CW rotations were documented in the internal Panormide and Imerese nappes, 80° in the more external Trapanese unit, and almost null rotations in the external Saccense thrust fronts of SW Sicily (Figure 3; Channell et al., 1990; Speranza et al., 2018). Similar to the southern Apennines, most of the rotations were late Miocene in age, and only about 20° rotations occurred during the Plio-Pleistocene (Grasso et al., 1987; Speranza et al., 2003).

Figure 3

Geologic map of Sicily and paleomagnetic vertical-axis rotations (circular arrows and relative CW rotation amount) evaluated with respect to Africa considering Jurassic-Eocene rocks from previous studies (Barberi et al., 1974; Channell et al., 1980, 1990; Grasso et al., 1983; Pellegrino et al., 2016; Speranza et al., 1999, 2003, 2018). The Peloritan terrane is stacked above the Sicilian Maghrebides. No rotations are recorded in the Hyblean Plateau, representing the Africa-affinity foreland of the Maghrebide chain. Black box indicates location of Figure 5.

In the Peloritan terrane, lower Pliocene-middle Pleistocene clays from the Milazzo-Messina area were paleomagnetically investigated at nine sites (Aifa et al., 1988; Cifelli et al., 2004; Grasso et al., 1987; Scheepers et al., 1994), and yielded a 10°–20° CW rotation occurring during Early-Mid Pleistocene times. No additional paleomagnetic data from Peloritan terrane exist.

All Sicilian rotations are due to Maghrebian thrust sheets emplacing since late Miocene with a rotational component, as the Hyblean Plateau—considered an African foreland fragment—has not undergone rotations with respect to Africa (Figure 3; Barberi et al., 1974; Grasso et al., 1983; Pellegrino et al., 2016).

3 Geological Setting of the Peloritan Terrane and Sampled Tectonic Units

The Peloritan terrane is a SSW-verging nappe stack including an Upper Complex made by high-grade (amphibolite facies) metamorphic nappes and isolated plutons (Aspromonte and Mela Units) stacked over medium grade (greenschist-lower amphibolite facies) rocks (Mandanici, Alì-Montagnareale), in turn overriding an external Lower Complex (San Marco d’Alunzio, San Pietro-Castelmola, Longi-Taormina, and Capo S. Andrea Units) made by very low grade metamorphic basement covered by un-metamorphosed Meso-Cenozoic sedimentary sequences (Cirrincione et al., 1999, 2015; Figure 4). Metamorphism affecting all units, except Lower Complex sediments, is both pre-Hercynian (Fiannacca et al., 2013) and Hercynian in age (314 Ma from Rb/Sr dating, Bonardi et al., 2001), with a 28-22 Ma (Oligocene) Alpine metamorphic overprint documented in the Aspromonte, Mandanici and Ali-Montagnareale Units (Atzori et al., 1994; Bonardi et al., 1987, 1992; Catalano et al., 2018; Cirrincione et al., 2012, 2015).

Figure 4

Tectono-stratigraphic scheme of the Peloritan terrane nappes, and number of sampled paleomagnetic sites at each tectonic unit. Units of the Peloritan terrane were first shortened in the middle Oligocene (blue thrust faults). Afterward, a younger compressive episode in the middle Burdigalian (red thrust faults) yielded the stacking of the Peloritan terrane above the Sicilide (SI), Monte Soro Flysch (SOR) and Maghrebides units. Formation coding: SCA: Scaglia; GCM: Calcari di Mazzarò; FRZ: Frazzanò Flysch; MAI: Maiolica; MD: Medolo; LOG-DOA: Calcari di Longi-Calcari e Dolomie di Taormina; VEP: Verrucano; RSA: Rosso Ammonitico; RMA: Rosso di San Marco. The Sicilde Unit encompasses the whole Cretaceous period and reaches a maximum thickness of 400 m. The local Rocca Novara sub-unit from which we sampled site PEL54 is not shown for simplification.

We sampled the sedimentary cover of the external San Marco d’Alunzio (hereinafter S. Marco), San Pietro-Castelmola (hereinafter S. Pietro), Longi-Taormina, and Capo S. Andrea Units (also called Gallodoro Unit by Servizio Geologico d’Italia (2010); Figures 4 and 5). The bottom of the sedimentary sequences is made by upper Triassic-lower Lias continental reddish conglomerates, sandstones and siltstones (Verrucano Fm.) unconformably lying above Hercynian basement phyllites. The lower Lias is represented by carbonate platform limestones called Rosso di S. Marco, Calcari e Dolomie di Taormina, Calcari di Longi, and Calcari di Mazzarò Fms. in the four different units, respectively. After the mid Lias, carbonate platform sedimentation continued in the S. Marco and Capo S. Andrea units, whereas pelagic mid Lias-lower Cretaceous limestones, marls and cherts (Medolo, Rosso Ammonitico, and Maiolica Fms.) deposited in the S. Pietro and Longi-Taormina Units. During the Mid-Late Jurassic, both the Rosso di S. Marco and Calcari di Mazzarò limestones evolved into seamounts where condensed and nodular reddish marly limestones (Ammonitico Rosso facies) deposited, both above the platform carbonates and within them as neptunian dikes (Figures 6a–6c). During Late Cretaceous-Eocene, whitish, reddish and greenish pelagic limestones, marls, and siltstones containing chert (“Scaglia” facies, widespread in all coeval Tethyan pelagic sequences) deposited throughout (Figures 6d and 6e). The late Eocene-lower Oligocene orogenic turbidites (sands and conglomerates) of the Frazzanò Flysch Fm. deposited above the Scaglia Fm. (Figure 4). Conglomerate clasts of the Frazzanò Fm. are made by medium-high grade metamorphic rocks, granites, and subordinate carbonates and sandstones. During mid Oligocene, the external Peloritan units were stacked in SSW-verging (in present-day coordinates) thrust fronts involving both phillitic basement and sedimentary cover (Figure 4). The deformed nappe stack was unconformably covered by upper Oligocene-lower Burdigalian turbiditic sandstones-conglomerates and subordinate clay layers of the Stilo-Capo d’Orlando Fm. (hereinafter Capo d’Orlando Fm.).

Figure 5

Geologic map of the Peloritan terrane external-intermediate tectonic units, and location of paleomagnetic sites from this study. (a) Extension of the study area through the Peloritan sedimentary cover that has been sampled at 55 sites. Sampled formations: GLO: Conglomerato Rosso (Upper Oligocene (?)); SCA: Scaglia (Upper Cretaceous-Eocene); RMA: Rosso di San Marco; RSA: Rosso Ammonitico; CGM: Calcari di Mazzarò (these three Fms. encompass the whole Jurassic Period); MED: Medolo (Lower Lias); VEP: Verrucano (Upper Trias-Hettangian). Red (black) marked sites yielded the “A” (“B”) magnetization directions. (b) Detail of the San Marco d’Alunzio sampling area. (c) Detail of the Capo San Andrea sampling area.

Figure 6

Field pictures from the Peloritan terrane. (a–c) Detail of the Rosso di San Marco Fm. exposed as red nodular limestone, encrinites and neptunian dikes, respectively. (d) Detail of the white limestone with red chert nodules of the Scaglia Fm. sampled at site PEL30. (e) Detail of the reddish silty-clayey Scaglia Fm. sampled at site PEL18. Red-marked samples, nearly all coming from a single clayey bed, escaped remagnetization and provided the primary A paleomagnetic direction (see diagram of sample PEL1814). Black-marked samples, coming from layers with larger silt content, provided the overprint B paleomagnetic direction, (see diagram of sample PEL1808). (f) Conglomerates and red sandy-silty layers of the Conglomerato Rosso Fm. at sampling site PEL39. (g) SW-verging thrust front juxtaposing the Rocca Novara Sub Unit (site PEL54) on top of the overturned Conglomerato Rosso Fm. (sites PEL51-52-53-55) in the Sant’Alessio area.

The Capo d’Orlando Fm. sealed the mid Oligocene thrust fronts and was deposited over all the Peloritan terrane, though it is mostly exposed on external units (Figure 3). Its thickness may reach 600 m, with mostly metamorphic and igneous clasts characterizing the conglomeratic levels (Aldega et al., 2011). It must be noted that an upper Oligocene-lower Burdigalian age is constantly assigned to the Capo d’Orlando Fm. by foraminifera and nannofossil analyses reported in all 1:50,000 geologic sheets published by Italian Geological Service (Servizio Geologico d’Italia, 2010, 2011, 2013a, 2013b), whereas solely de Capoa et al. (2000, 2004)—always relying on nannofossil investigation—suggested a mid-Burdigalian age. At places, the Capo d’Orlando Fm. rests in stratigraphic continuity above the Conglomerato Rosso Fm. (Figure 6f), a continental fluvial-alluvial sequence made by conglomerates and reddish sandy-silty matrix and layers tentatively attributed to the Late Oligocene (Servizio Geologico d’Italia, 2013b). During mid Burdigalian, the external Peloritan units underwent a second SSW-directed (always in present-days coordinates) shortening (Figure 6g) and were stacked above the Cretaceous chaotic pelagic sediments and turbidite layers of the Sicilide Units and Mt. Soro Fm.—inferred to represent deep-water deposits of the Alpine Tethys (Catalano et al., 2013)—in turn tectonically juxtaposed over the Maghrebian chain of Sicily (Figures 3-5). This event likely caused the backthrusting with gravity-driven mechanisms of the Sicilide sediments above the Capo d’Orlando Fm. that formed the so-called “Antisicilide nappe” (Corrado et al., 2009; Lentini & Vezzani, 1978).

The whole Peloritan compressive stack was unconformably covered by virtually undeformed Upper Burdigalian-Lower Langhian bioclastic calcarenites and arkoses (Calcareniti di Floresta), and lower Serravallian to mid Pleistocene marine terrigenous sediments mostly exposed along the Tyrrhenian and Ionian margins of the internal Peloritan Units. Furthermore, vitrinite reflectance data from the Capo d’Orlando Fm. suggest that the internal Peloritan units underwent a late Langhian-early Serravallian out-of-sequence thrust tectonics (Aldega et al., 2011), consistently with apatite fission track and U-Th/He low-temperature thermochronology data (Olivetti et al., 2010).

The stacking of the Peloritan block onto the Sicilide Unit, Mt. Soro Fm., and the Maghrebide chain of Sicily is firmly constrained in mid Burdigalian times (18-17 Ma), as (a) it post-dates the upper Oligocene-lower Burdigalian Capo d’Orlando Fm., involved in the external and frontal thrust fronts of the Peloritan terrane; (b) it pre-dates the Upper Burdigalian—Lower Langhian Calcareniti di Floresta that lie virtually undeformed above the Peloritan stack; (c) it must be roughly coeval to a mid-Burdigalian exhumation due to thrust activity in the Sicilide nappe lying just ahead the Peloritan front, that sourced the emplacement of the Antisicilide nappe above the Peloritan terrane (Aldega et al., 2011).

No significant evidence for regional-scale strike-slip tectonics exists in the field, although several regional papers depicted in the past the SW boundary of the Peloritan terrane as a dextral transcurrent margin (“Taormina Line,” e.g. Bonardi et al., 1976; Amodio-Morelli et al., 1976; Lentini et al., 1995). Structural and anisotropy of magnetic susceptibility (AMS) data from the mid Lias Medolo Fm. of the S. Pietro Unit (SE external Peloritan terrane) consistently confirm WNW structural trends and SSW shortening direction (Somma, 2006; Somma et al., 2005). However, it must be noted that Vignaroli et al. (2008) documented a top-to-SSE shortening direction from predominant metamorphic basement and subordinate limestones of the Mandanici, Alì, and external units exposed along the Ionian coast, just N of the zone studied by Somma et al. (2005) and Somma (2006).

Apart from the out-of-sequence shortening episode documented on the internal units in late Langhian-early Serravallian times (14–13 Ma), the whole Peloritan terrane underwent extensional tectonics since late Serravallian (∼12 Ma) onward. Extension onset is suggested by sediment geometry of the S. Pier Niceto Fm., a thick (up to 600 m) Serravallian-lower Messinian terrigenous package exposed above the internal Peloritan units, whose deposition was clearly controlled by extensional tectonics (Lentini et al., 2000; Servizio Geologico d’Italia, 2010, 2011, 2013b). Therefore, the onset age of extensional tectonics in the Peloritan terrane is fully comparable to that observed in Calabria as a basin of the Tyrrhenian margin (Mattei et al., 2002).

Extensional tectonics continued for the whole Plio-Pleistocene times (Catalano et al., 2008; Monaco & Tortorici, 2000; Nigro & Sulli, 1995), and is testified today by destructive historical seismicity such as the 1908 earthquake striking Messina and Reggio Calabria, the strongest Italian earthquake of the XX century (Boschi et al., 2000; Guidoboni et al., 2007; Catalago Parametrico dei Terremoti Italiani https://emidius.mi.ingv.it/CPTI15-DBMI15/). Extensional seismicity is associated to a strong late Pleistocene-Holocene regional uplift reaching 2 mm/yr along the Ionian coast of the Peloritan terrane (Spampinato et al., 2012).

It is noteworthy that no ophiolites from Alpine Tethys oceanic crust are tectonically interposed between the European-affinity Peloritan terrane and the Sicilian Maghrebides that represent the deformed African margin. Such setting is markedly different from that of N Calabria and the northern Apennines, where ophiolites of the Alpine Tethys are exposed both in un-metamorphosed and blueschist facies (e.g., Rossetti et al., 2001, 2004). Therefore, either (a) no oceanic crust occurred between Europe and Africa along the Peloritan terrane margin, or (b) the oceanic crust—possibly representing the substratum of the Sicilide and Mt. Soro Cretaceous deep-sea sediments—was tectonically elided and decoupled from sedimentary cover, or (c) it forms a buried duplex system hidden at depth below the Peloritan nappe stack (Patacca & Scandone, 2011). The latter hypothesis is unlikely, as ophiolites are intensely magnetic yet both the Peloritan Mts. and the whole N Sicily are characterized by constantly negative magnetic anomalies (Caratori Tontini et al., 2004).

4 Paleomagnetic Sampling and Methods

During an overall 6 weeks-long campaign spanning years 2022 and 2023, we collected a total number of 574 oriented paleomagnetic cores at 55 sites from the San Marco (24 sites), S. Pietro (5), Longi-Taormina (12), Capo S. Andrea (7) units, and Rocca Novara subunit (1), and six sites from the reddish sandy-silty layers of the upper Oligocene Conglomerato Rosso Fm. that unconformably covers the Mandanici Unit (Figures 4 and 5). One site was sampled in the reddish silty layers of the upper Trias-lower Lias Verrucano Fm., 17 and 7 sites in the reddish nodular limestones and marls and sedimentary dykes (respectively) of the mid-upper Jurassic Rosso San Marco and Calcari di Mazzarò Fms., 4 sites in the limestones of the mid Lias Medolo Fm., 2 sites in the mid-upper Jurassic Rosso Ammonitico Fm., 17 sites in marls, silts, and limestones of the upper Cretaceous-middle Eocene Scaglia Fm, and 1 site in red marly layers of the Cretaceous-Eocene Rocca Novara Fm. Site locations and ages are detailed in Figures 4 and 5 and Table S1 in Supporting Information S1. Hereinafter we refer to the Rosso di S. Marco, Rosso Ammonitico and Calcari di Mazzarò sites as Jurassic (mid Lias-upper Malm) Ammonitico Rosso sites, as their sedimentological features and ages are similar.

At each site, we drilled 9–19 cores (10 on average) using a petrol-powered portable drill cooled by water, and oriented them in situ using both a Sun and a magnetic compass, corrected for the local geomagnetic declination in 2022/2023 (∼4°E according to NOAA's National Geophysical Data Center). Bedding attitudes were highly variables, being overturned due to thrust tectonics at 8 sites (among them, all 6 Conglomerato Rosso Fm. sites). The bedding was always apparent in the field (Table S1 in Supporting Information S1) except for site PEL42 for which bedding was inferred as parallel to magnetic foliation after measuring the AMS of a specimen from each core, using an AGICO Kappabridge KLY-5 susceptibility bridge. AMS data were elaborated using Jelínek and Kropáček (1978) statistics.

The cores were cut into standard specimens of 22 mm height and paleomagnetic measurements were performed in the shielded room of the “Renato Funiciello paleomagnetic laboratory” at the Istituto Nazionale di Geofisica e Vulcanologia (Rome, Italy), using a 2G Enterprises direct current superconducting quantum interface device cryogenic magnetometer. All samples were thermally demagnetized using a Pyrox shielded oven in 10–14 steps up to 690°C. Assuming 600°–690°C as the temperature interval where primary magnetization from detrital hematite is isolated (Jiang et al., 2015), wide (50°C) temperature increments were used from 200°C to 600°C, and smaller (30°C) increments between 600°C and 690°C.

Demagnetization data were plotted on orthogonal vector diagrams (Zijderveld, 1967), and principal component analysis was performed to isolate magnetization components (Kirschvink, 1980). Site-mean paleomagnetic directions were calculated using Fisher's (1953) statistics and plotted on equal-area projections, using the Remasoft software (Chadima & Hrouda, 2006).

Fold (McFadden, 1990; Tauxe & Watson, 1994) and reversal (McFadden & McElhinny, 1990) tests were performed on groups of statistically similar site-mean directions. Paleomagnetic rotation and flattening values were evaluated according to Demarest (1983). Pre-tilting magnetization directions (Table 1) were compared to Europe paleo-poles from Torsvik et al. (2012). Common mean direction (CMD) tests (Heslop et al., 2023; Tauxe et al., 1991) were performed on primary (see below) Jurassic and Cretaceous-Eocene paleomagnetic directions to test whether they are statistically distinguishable. Vertical axis rotations from secondary magnetization directions were calculated with respect to the geographic North considering the in-situ directional values (Table 2), as negligible Africa/Europe paleo-declinations are expected for the late Cenozoic.

Table 1. “A” Paleomagnetic Direction From the Peloritan Terrane and Relative Vertical-Axis Rotations

Site	Lithology	Fm.	Unit	Age	Age (Ma)	Bedding (dipdir-dip) ^++overturned	In situ direction						Tilt-corr. direction				Vertical-axis rotations
							n/N	State	D (°)	I (°)	k	α95 (°)	D (°)	I (°)	k	α95 (°)	Ppole (Ma)	R (°)	ΔR (°)	F (°)	ΔF (°)
PEL11	Reddish limestones	MED	LTA	Pleinsbachian	190–182	39–76	7/11	R	358.2	−59.2	14.9	16.2	243.3	−35.7	14.9	6.2	180	37.9	6.7	15.4	5.6
PEL13	Red marls	RSA	STP	Toarcian-Tithonian	182–145	^++177-154	9/9	N	48.4	8.7	36.4	8.7	125.7	7.8	36.4	8.6	160	109.0	8.0	34.6	8.5
PEL19	Red limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	186–52	9/10	N	55.9	32.1	16.2	13.2	103.4	49.2	16.2	13.2	160	86.7	16.5	−6.7	11.5
PEL26	Neptunian dike red limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	7–25	7/10	R	321.9	−53.6	11.9	18.2	282.4	−65.1	11.9	18.2	160	85.8	37.6	−22.7	15.1
PEL27	Nodular limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	sub-hzt	7/10	R	302.2	−24.0	11.2	18.9	302.2	−24.0	11.2	18.9	160	105.6	16.8	18.5	15.6
PEL33	Red nodular limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	359–19	6/10	R	306.6	2.0	84.2	7.3	305.6	−9.5	83.8	7.4	160	108.9	7.3	33.0	7.8
ROSSO AMMONITICO MEAN ROTATION																		99.2	12.2
PEL18	Red silty marls	SCA	LTA	Upp. Cretaceous- Eocene	100–40	69–37	11/19	N	142.3	20.5	12.3	13.5	133.6	6.8	12.3	13.5	70	129.6	10.8	39.7	10.8
PEL30	Marls w. red chert	SCA	LTA	Upp. Cretaceous- Eocene	100–40	5–16	8/10	N	136.4	5.8	11.0	17.4	134.0	16.1	11.0	17.4	70	130.0	14.3	30.4	13.8
PEL31	Limestone w. cherts	SCA	LTA	Upp. Cretaceous- Eocene	100–40	168–12	4/10	R	304.2	−32.4	21.2	20.4	308.4	−23.4	21.2	20.4	70	124.4	17.6	23.1	16.1
PEL34	Red marls	SCA	LTA	Upp. Cretaceous- Eocene	100–40	55–13	6/10	N	121.2	12.6	14.8	18	118.8	7.5	15	17.8	70	114.8	14.2	39.0	14.1
						49–16
PEL37	Red marls	SCA	LTA	Upp. Cretaceous- Eocene	100–40	^++206-157	9/10	N	63.4	−19.2	13.1	14.8	160.4	36.6	13.0	14.8	70	156.4	14.6	9.9	11.8
PEL50	Silty marls	SCA	CSA	Upp. Cretaceous- Eocene	100–40	291–27	7/10	R	273.5	−20.2	15.2	16	267.2	−45.6	15.1	16	70	83.1	18.2	0.7	12.7
SCAGLIA MEAN ROTATION																		131.1	15.4
PEL39	Red arenites/siltstones	GLO	MND	Upper Oligocene (?)	27–23	^++97-119	8/10	R	65.4	−9.5	9.7	18.7	304.7	−41.8	13.8	15.5	20	120.1	16.6	11.5	12.3
						^++73-134
PEL40	Red arenites/siltstones	GLO	MND	Upper Oligocene (?)	27–23	^++97-119	7/10	R	37.6	−26.2	21.8	13.2	328.8	−10.7	21.9	13.2	20	144.2	10.8	42.6	10.5
PEL51	Red arenites/siltstones	GLO	MND	Upper Oligocene (?)	27–23	^++200-130	3/10	R	235.3	10.4	92	12.9	323.5	−46.9	92.1	12.9	20	138.9	15.1	6.3	10.3
PEL55	Red arenites/siltstones	GLO	MND	Upper Oligocene (?)	27–23	^++205-146	6/9	N	60.6	−18.1	82.3	7.3	152.8	45.5	85.8	7.3	20	148.2	8.5	7.7	6.1
CONGLOMERATO ROSSO MEAN ROTATION																		137.8	12.4

• Note. Sites are listed by sampled formation/age; geographic coordinates of sampled sites are provided in Table S1 of Supporting Information S1; SITE: excluded from calculation of mean vertical-axis rotation; formations coding: MED: Medolo, RSA: Rosso Ammonitico, RMA: Rosso di San Marco, SCA: Scaglia, GLO: Conglomerato Rosso; tectonic unit coding: LTA: Longi-Taormina, STP: San Pietro, SMA: San Marco, CSA: Capo San Andrea, MND: Mandanici; bedding sub-hzt = sub-horizontal; multiple beddings indicate folded sites; beddings marked with ⁺⁺ are overturned; n/N: number of samples giving reliable results/number of studied samples at a site. State N and R indicate normal- and reverse-polarity magnetization, respectively. D and I: site-mean declination and inclination calculated before and after tilt correction; k and α₉₅: statistical parameters after Fisher (1953). Vertical-axis rotations (R) and flattening (F) calculated using tilt-corrected directions compared to corresponding Europe paleo-pole (Ppoles) from Torsvik et al. (2012).

Table 2. “B” Paleomagnetic Direction From the Peloritan Terrane and Relative Vertical-Axis Rotations

Site	Lithology	Fm.	Unit	Age	Age (Ma)	Bedding (dipdir-dip)	In situ direction						Tilt-corr. direction				Vertical-axis rotations
							n/N	STATE	D (°)	I (°)	k	α95 (°)	D (°)	I (°)	k	α95 (°)	R (°)	ΔR (°)	F (°)	ΔF (°)
PEL02	Silty marls	RMA	SMA	Pleinsbachian-Tithonian	190–145	295–24	11/11	N	27.2	44.6	43.4	7.0	4.9	40.7	43.4	7.0	27.1	9.8	12.9	7.0
PEL06	Red limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	248–11	11/11	N	14.4	22.9	20.3	10.4	10.0	29.1	20.3	10.4	14.3	11.3	34.5	10.4
PEL07	Red siltstones	RMA	SMA	Pleinsbachian-Tithonian	190–145	sub-hzt	6/10	N	35.3	12.8	29.9	12.4	35.3	12.8	29.9	12.4	35.2	12.7	44.6	12.4
PEL08	Red siltstones	RMA	SMA	Pleinsbachian-Tithonian	190–145	sub-hzt	9/10	N	24.7	31.0	11.3	16.0	24.7	31.0	11.3	16.0	24.6	18.7	26.4	16.0
PEL16	Pink limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	290–25	6/11	R	240.8	−29.2	18.3	16.1	225.2	−43.0	18.3	16.1	60.7	18.4	28.2	16.1
PEL17	Reddish marls	SCA	LTA	Upp. Cretaceous- Eocene	100–40	55–16	6/10	R	215.2	−38.5	105.8	6.5	218.3	−23.3	105.6	6.6	35.1	8.3	19.0	6.5
PEL18	Red silty marls	SCA	LTA	Lower Eocene (?)	100–40	69–37	8/10	N	44.2	41.2	22.8	11.8	50.5	6.6	22.8	11.8	44.1	15.7	16.3	11.8
PEL21	Red limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	sub-hzt	5/10	N	34.8	29.5	71.9	9.1	34.8	29.5	71.9	9.1	34.7	10.5	27.9	9.1
PEL24	Red limestones	RMA	SMA	Pleinsbachian-Tithonian	190–145	186–52	10/10	R	218.2	−28.7	26.4	9.6	266.4	−61.7	26.4	9.6	38.1	10.9	28.7	9.6
PEL25	Red marls	RMA	SMA	Pleinsbachian-Tithonian	190–145	239–40	8/10	N	31.9	60.9	10.6	15.5	282.9	71.4	10.6	15.5	31.8	31.9	−3.5	15.5
PEL32	Red marls	SCA	LTA	Upp. Cretaceous- Eocene	100–40	44–22	9/10	N	26.5	44.6	20.0	11.8	30.5	23.4	20.0	11.8	26.4	16.6	12.8	11.8
						23–43
PEL35	Red-greenish marls and sandstones	SCA	SMA	Upp. Cretaceous- Eocene	100–40	123–16	10/10	N	3.4	42.8	22.4	10.4	11.3	32.6	9.6	16.5	3.3	14.2	14.6	10.4
						111–9
PEL42	Claystones	RSA	STP	Toarcian-Tithonian	182–145	^#178–25	10/10	N	15.7	45.6	26.64	9.9	33.2	68.3	24.6	9.9	15.6	14.1	11.6	9.90
PEL43	Limestones w. red chert	MED	STP	Pleinsbachian	190–182	300–24	6/10	N	53.9	37.8	18.1	16.2	38.8	36.4	12.3	19.9	53.8	20.5	19.5	16.2
						344–17
PEL45	Pinky limestones	SCA	CSA	Upp. Cretaceous- Eocene	100–40	288–27	9/10	N	43.4	23.0	13.8	14.4	34.9	33	14.9	14.2	43.3	15.6	34.2	14.4
						248–11
PEL46	Red limestones/encrinites	CGM	CSA	Pleinsbachian-Tithonian	190–145	332–32	11/10	R	223.1	−29.5	17.5	11.2	210.7	−15.6	17.5	11.2	43.0	12.9	27.7	11.2
PEL47	Red limestones/encrinites	CGM	CSA	Pleinsbachian-Tithonian	190–145	340–23	8/10	R	222.1	−37.5	11.4	17.2	210.4	−24.5	11.4	17.1	42.0	21.7	19.7	17.2
PEL49	Limestones (dike and strata)	CGM	CSA	Pleinsbachian-Tithonian	190–145	351–44	7/10	R	227.6	−20.4	11.7	18.4	222.9	6.2	11.7	18.4	47.5	19.6	36.8	18.4
PEL53	Red arenites/siltstones	GLO	MND	Upper Oligocene (?)	27–23	^++232-136	7/10	N	34.9	33.6	12.8	17.5	246.3	8.9	12.8	17.6	34.8	21.0	23.7	17.5
PEL54	Red limestones/siltstones	RCN	RCN	Cretaceous-Eocene	145–40	21–53	8/10	N/R	15.4	58.2	18.9	13.1	18.0	5.4	18.9	13.1	15.3	24.9	−0.9	13.1

• Note. Geographic coordinates of sampled sites are provided in Table S1 of Supporting Information S1; formations coding: RMA: Rosso di San Marco, RSA: Rosso Ammonitico, SCA: Scaglia, MED: Medolo, CGM: Calcari di Mazzarò, RCN: Rocca Novara; tectonic unit coding: SMA: San Marco, LTA: Longi-Taormina, STP: San Pietro, CSA: Capo San Andrea, MND: Mandanici, RCN: Rocca Novara; bedding sub-hzt = sub-horizontal; multiple beddings indicate folded sites, ^#bedding from anisotropy of magnetic susceptibility measurements; beddings marked with ⁺⁺ are overturned; n/N: number of samples giving reliable results/number of studied samples at a site; State N and R indicate normal- and reverse-polarity magnetization, respectively; D and I: site-mean declination and inclination calculated before and after tilt correction; k and α₉₅: statistical parameters after Fisher (1953); vertical-axis rotations calculated using in-situ directions compared to the geographic North.

Finally, the magnetic mineralogy was investigated for one representative specimen per site by the thermal demagnetization of a three-component isothermal remanent magnetization (IRM) according to Lowrie (1990). A magnetic field of 2.7, 0.6, and 0.12 T was imparted along the three sample axes with a 2G Enterprises pulse magnetizer. Samples were subsequently thermally demagnetized in 10 steps up to 700°C.

5 Results

5.1 Magnetic Mineralogy

The magnetic mineralogy is investigated considering both the natural remanent magnetization (NRM) thermal decay curves observed on all specimens, and the thermal demagnetization of a three-component IRM, performed on one representative specimen per site (Figure 7 and Figures S1–S3 in Supporting Information S1).

Figure 7

Orthogonal vector diagrams (in-situ coordinates) of typical demagnetization data, and thermal demagnetization of a three-components isothermal remanent magnetization (Lowrie, 1990) for representative specimens yielding the A and B magnetization directions. Progressive thermal demagnetization steps are in °C.

The Ammonitico Rosso (Rosso di San Marco; Figure 7a) NRM thermal decay curves are demagnetized at 610°C along a mostly concave path. Thermal demagnetization of a three-axes IRM (Figure 7d) indicates the presence of a high- and intermediate-coercivity fractions (0.12 < coercivity ≤ 2.7 T) that unblock at 610–700°C, whereas the soft-coercivity fraction is virtually absent.

The Scaglia Fm. samples are demagnetized at 640–670°C with in most cases a nearly linear remanence decay (Figures 7b and 7g). The IRM thermal demagnetization (Figures 7e and 7l) indicates the presence of intermediate and high coercivity fractions unblocked at 700°C. A soft-coercivity fraction (<0.12 T) unblocking at 600°C is also present, although definitely subordinate with respect to hard components. The Conglomerato Rosso NRM thermal decay curves show complete unblocking at 680°C, and the IRM diagrams show a main high-coercivity fraction demagnetizing at 700°C yielding a markedly convex decay pattern (Figure 7f).

The NRM of the Medolo (Figure 7h) and Ammonitico Rosso (Calcari di Mazzarò limestones; Figure 7i) is annulled at 540–580°C, and the IRM diagrams show both a high-intermediate and soft coercivity fractions unblocked at 700° and 580°C respectively (Figures 7m and 7n), indicating the coexistence of both hematite and magnetite.

We conclude that remanence of the studied samples is mostly carried by hematite showing a mixture of concave and convex decay curves (Jiang et al., 2015), and by subordinate magnetite.

5.2 Paleomagnetic Directions and Field Tests

Thirty-eight out of 55 sites gave reliable results and yielded a characteristic magnetization component (ChRM) in the 350–680°C temperature interval (Figure 7). The remaining 17 sites are characterized by scattered or erratic demagnetization diagrams. Only 33 samples from 14 sites gave low-temperature (LT) and high-temperature (HT) components isolated in the 250–500 and 380–690°C temperature intervals, respectively (see summary in Table S2). The α₉₅ values relative to the site-mean paleomagnetic directions vary from 6.2° to 20.4° (13.3° on average).

Confidence cones of in-situ directions from sites PEL03 and 04 overlap with local geocentric axial dipole (GAD) field direction (D = 0°; I = 59°; Figure 8). Thus, we infer that such sites were recently remagnetized, and excluded them from any further considerations.

Figure 8

Equal area projection of the site-mean paleomagnetic directions from the Peloritan terrane. Solid/open symbols represent projection of the lower/upper hemisphere, respectively. Light-gray circles indicate the projections of the α₉₅ confidence cones. Expected directions at 160, 70, and 20 Ma of Europe used to calculate vertical-axis rotation are shown in the upper-right stereonet. Results of bootstrap fold tests (Tauxe & Watson, 1994) are positive and negative for the A and B direction groups, respectively. Group A test include sites PEL11-13-18-19-26-30-31-33-34-37-39-40-50-51-55; group B test include sites PEL02-06-16-17-18-24-25-32-42-43-45-46-47-49.

In the remaining 36 sites, two main paleomagnetic directions groups (both showing dual polarities) were observed (Figures S4 and S5 in Supporting Information S1). The “A” paleomagnetic directions (including ChRMs and HT components from 16 sites) are scattered in in-situ coordinates but cluster to the SE when considered tilt-corrected and in the normal polarity state (Figure 8 and Table 1). Such sites support a positive fold test at a 99% significance level (Table S3 in Supporting Information S1 and Figure 8) and an indeterminate reversal test (Table S4 in Supporting Information S1). Conversely, the “B” paleomagnetic directions (including ChRMs and LT components from 20 sites) trend NE-ward when considered in in-situ coordinates and normal polarity state, and are scattered when tilt-corrected (Figure 8 and Table 2). The B directions fail both the fold and reversal tests (Tables S3 and S4 in Supporting Information S1).

Both the A and B directions are retrieved from all sampled formations (excluding Verrucano sandstones, yielding scattered diagrams), and in some cases from the same sampling site (Figure 6e). In particular, the pre-tilting A directions were retrieved in 1 out of 2 (50%) Medolo sites, in 5 out of 17 (29%) Ammonitico Rosso sites, in 5 out of 10 (50%) Scaglia sites, and in 4 out of 6 (66%) Conglomerato Rosso sites.

5.3 Paleomagnetic Directions Versus Magnetic Mineralogy

Considering each formation, similar demagnetization patterns are observed in specimens carrying the A (primary) and B (overprint) direction. Uniquely the Conglomerato Rosso sites yielding the A direction show a markedly convex thermal magnetization decay. As the shape of the hematite thermal decay curve (concave vs. convex) may be used to assess the detrital, versus chemical origin of hematite (Jiang et al., 2015), our magnetic mineralogy data coupled with the results of field tests suggest that the A directions reflect primary detrital hematite remanence, whereas B directions formed later, after chemical grow of hematite that post-dated tectonic deformation (mid Burdigalian). Frequency histograms of the unblocking temperature of the A and B direction indeed show that the A direction is more frequently associated to a remanence drop between 600 and 700°C, that is expected to be related to detrital (primary) hematite (Figure S6 in Supporting Information S1). The ratio of primary/CRM hematite sites is maximum in the Conglomerator Rosso (4 vs. 2 sites), decreases in the Scaglia Fm. (5 vs. 5), and is minimal in Ammonitico Rosso sites (5 vs. 12).

To sum up, magnetic mineralogy data gives some evidence to support the A and B directions discrimination (mostly in the Conglomerato Rosso Fm. case), but definitely it cannot be used as stand-alone criterion. Directions themselves and field tests results represent the discriminating criterion, and in fact we refer to paleomagentic “directions” rather than “components.”

6 Magnetization Acquisition Age(s) and Orogenic Rotations

As the Peloritan terrane is considered a piece of European crust, fragmented and dispersed after Early Oligocene (30 Ma), we compared the pre-tilting A paleomagnetic directions to those expected for Europe (Figure 8; Torsvik et al., 2012). The A paleomagnetic directions translate to 38°–156° CW rotations with respect to Europe (Table 1). The mid Lias Medolo PEL11 site yields a significantly smaller 38° ± 7° CW rotation, and the unique A direction from the Capo S. Andrea Unit (site PEL50) gives also a different 83° ± 18° CW rotation with respect to other Scaglia sites. Sites PEL11 and PEL50 are therefore excluded from further considerations (Table 1), being unclear whether their different behavior is due to sedimentary or local tectonic features.

By averaging rotations values from sites of similar age from San Marco and Longi-Taormina Units we calculate 99° ± 12° and 131° ± 15° CW rotations for the Jurassic Ammonitico Rosso (five sites) and upper Cretaceous-Eocene Scaglia Fm. (five sites), respectively, and a 138° ± 12° CW rotation for the upper Oligocene Conglomerato Rosso Fm. (four sites).

The significantly different rotation of Jurassic and upper Cretaceous-Eocene sediments will be addressed in Section 7, whereas here we discuss upper Cretaceous-Eocene and upper Oligocene rotation data similarity and its implications. Coherent rotation values characterize the external Longi-Taormina Unit (hosting the Scaglia sites) and the intermediate Mandanici Unit (lying below the Conglomerato Rosso Fm., Figures 4 and 5), in turn resting below internal high-grade metamorphic units; external units are also exposed as isolate tectonic windows in the central-southern part of the terrane. Thus, paleomagnetic data indicate that the middle Oligocene Peloritan terrane shortening event (Figure 4) did not yield individual rotations among Peloritan nappes, and that the whole terrane underwent a semi-rigid post-Late Oligocene ∼130° CW rotation.

The post-Late Oligocene ∼130° CW rotations of the Peloritan terrane turns out to be fully similar to the 120°–140° CW rotation documented in Jurassic-Eocene sediments of the Panormide and Imerese Units of the W Sicily Maghrebides (Channell et al., 1990; Speranza et al., 2018; Figure 3). A 90°–100° CW rotation was also observed in upper Cretaceous-Eocene limestones from the Madonie Mts. of central northern Sicily (Channell et al., 1990), at Cozzo Disi in central Sicily and Mt. Judica-Mt. Scalpello ridges at the SE Maghrebide front (Speranza et al., 2003). Such data show that the whole internal Sicilian Maghrebides—previously forming the African margin of the Neo Tethys—underwent a 100°–140° CW rotation that occurred mostly during Serravallian-Messinian times (12–5 Ma, Speranza et al., 2018).

We suggest that the ∼130° CW rotation of the Peloritan terrane is due to the late Miocene rotation of the whole internal Maghrebide chain that passively carried (and rotated) the Peloritan block stacked above it. Such mechanism matches the rotational evolutionary model proposed for the Maghrebide belt of W Sicily, where CW rotation decrease stepwise from internal Panormide-Imerese Units (130°), to the more external Trapanese Unit (80°), to the Saccense Unit at chain front where negligible rotations were documented (Channell et al., 1990; Speranza et al., 2018; Figure 3). This rotation setting was interpreted in term of a late Miocene-Early Pleistocene forward propagation of nappes rotating synchronous with thrusting and passively rotating the whole nappe stack lying above them. Such kinematics implies that the nappe located on top of the orogenic stack record the sum of all rotations, and that rotation values decrease stepwise from internal to external thrust fronts (Oldow et al., 1990; Speranza et al., 2018).

According to paleomagnetic data by Grasso et al. (1987), Aifa et al. (1988), Scheepers et al. (1994), and Cifelli et al. (2004), the Peloritan terrane underwent only a 10°–20° CW rotation during Early-Mid Pleistocene, indicating that most of the 130° CW rotations occurred in late Miocene times, Plio-Pleistocene rotations being largely subordinate. This chronology is fully comparable with rotation timing previously documented on both limbs of the Maghrebide-Apennine orogenic salient, that is, the southern Apennines and the Sicilian Maghrebides (Gattacceca & Speranza, 2002; Speranza et al., 2003).

The Peloritan terrane underwent extensional tectonics since late Serravallian times (Lentini & Carbone, 2014). Thus, CW rotations were likely synchronous to extensional tectonics, implying that since Serravallian (12 Ma) the Peloritan terrane has been characterized by a “tectonic layering,” with thrust tectonics (and rotations) affecting Maghrebide thrust fronts at depth and extension occurring up-section on the Peloritan upper crust. Tectonic layering often occurs in mountain chains, and surely characterized the nearby Calabrian terrane that since Serravallian times underwent a 500 km ESE-ward drift on top of migrating thrust fronts synchronous to shallow extensional tectonics that guided the deposition of a thick post-orogenic sedimentary blanket (Mattei et al., 2002).

The acquisition of the post-tilting B direction certainly post-dates mid Burdigalian (18–17 Ma) that is the age of the last SSW-directed shortening-folding (in present-day coordinates) in the external Peloritan nappes, and stacking above the Maghrebian chain (Figure 4). Rotations of the B direction were evaluated with respect to geographic North, as neither Africa nor Europe underwent significant rotations during the last 20 Ma. The obtained CW rotations amounts vary from 0° to 60° (Table 2). The six reverse-polarity sites are tightly clustered in in-situ coordinates and yield a 44° ± 9° CW rotation (Figure 8), indicating acquisition during a late Miocene reverse-polarity chron. Considering the variability of rotation magnitudes and the dual polarity nature, we conclude that the B paleomagnetic direction must have been acquired over a prolonged time window spanning at least two polarity chrons, synchronous to late Miocene rotations and extensional tectonics, and that it was rotated CW by variable amounts up to ∼60° (Figure 8 and Table 2).

Normal faults may have enabled fluid circulation, in turn promoting magnetic overprint by both remobilizing and oxidizing (chemical overprint) existing magnetic minerals. We note that remagnetization affected 70%, 40%, and 20% of the Ammonitico Rosso, Scaglia, and Conglomerato Rosso sites. Thus, overprint mostly occurred within originally deeper massive limestones, and was virtually absent in shallower detrital sediments resting on top of the nappe stack. This indicates extension-driven fluid circulation and remagnetization in deep carbonate strata sealed by shallower detrital layers (Frazzanò and Capo d’Orlando Fms. Figure 4). The effects of fluid circulation and chemical overprint are clear at Scaglia site PEL18 (Figure 6e). Here only a single clayey (thus more impermeable) bed escaped overprint and yielded the A paleomagnetic direction, whereas the rest of the outcrop made by more permeable siltstones was massively overprinted by the B direction.

7 The Peloritan Terrane: From Greater Iberia to the Neo Apennine-Maghrebide Arc

Vertical-axis CW rotations calculated averaging rotational values (Table 1) documented in the Jurassic (99° ± 12°) and upper Cretaceous-Eocene (131° ± 15°) sediments from the S. Marco and Longi-Taormina Units imply a ∼30° CCW rotation of the Peloritan crust during Early Cretaceous (145–100 Ma). If rotations are evaluated after averaging out site-mean directions (Table S5 and Figure S7 in Supporting Information S1) the Jurassic-upper Cretaceous rotational difference is not significant (102 ± 25° vs. 130 ± 15°), likely due to the low data number and the high scatter of Jurassic inclination data (Figure 8 and Table 1). However, the 30° rotation difference is confirmed if instead more numerous ChRMs/HTs from coeval sediments are averaged out (102 ± 9° vs. 133 ± 8), considering sample-mean direction, a procedure that has been used in some works (e.g., Advokaat et al., 2014). Of these three methods for calculating average rotation values, we consider the first (Table 1) as more appropriate for sediments in orogenic belts, as it disregards inclination data that may be highly scattered and biased due to compaction/diagenesis events (e.g., Arason & Levi, 1990). Moreover, the results of the CMD tests (Heslop et al., 2023; Tauxe et al., 1991) considering sample directions—as the low site-mean direction number would bias the results (e.g., Heslop et al., 2023)—indeed indicate that Jurassic and Cretaceous-Eocene data belong to statistically separated populations (Figures S8 and S9 in Supporting Information S1).

Such early Cretaceous 30° CCW rotation is fully comparable to the Iberian CCW rotation synchronous to Bay of Biscay spreading, bracketed in the 150-120 Ma time window (Gong et al., 2008; Neres et al., 2012, 2013). This is the first firm evidence that—besides S Sardinia and Calabria (Siravo et al., 2022, 2023)—also the Peloritan block was a fragment of “Greater Iberia.” Our data definitely support one end-member among Iberian rotation models (Figure 2a) suggesting an Iberia rotation pole located on N Europe, sinistral shear along the Pyrenees, and E-ward Iberia drift along with S Sardinia and AlKaPeCa blocks (Barnett-Moore et al., 2016, 2017; Dewey et al., 1989; Handy et al., 2010; Le Breton et al., 2021; Siravo et al., 2023; Stampfli & Borel, 2002; Wortmann et al., 2001).

The question arises as to what happened on the eastern Greater Iberia margin during its E-ward directed drift. An oblique collision with Alpine Tethys is kinematically necessary, with synchronous sinistral shear due to coeval oblique motion between Africa and Europe (e.g., Dewey et al., 1989; Wortmann et al., 2001). We suggest that Early Cretaceous oblique collision between Greater Iberia and Alpine Tethys gave rise to ridges whose dismantling yielded the Mt. Soro Fm. turbidites (Early Cretaceous; Barbera et al., 2011; Torricelli, 2001) and other clastic deposits documented in coeval sediments of the Longobucco sequence of N Calabria (Santantonio & Fabbi, 2020) and the Kabylie blocks (Wildi, 1983). Early Cretaceous deformation event in the AlKaPeCa terranes is also suggested by the rather systematic occurrence of a 130 Ma radiometric age in the basement rocks of the Calabrian (Del Moro et al., 1986; Laurenzi et al., 1986; Schenk, 1980), Peloritan (Atzori et al., 1990) and Kabylie terranes (Cheilletz et al., 1999; Mahdjoub et al., 1997). Moreover, docking between Iberian and Alpine Tethys crusts may have induced a crustal uplift testified by late Early Cretaceous bauxite pockets and unconformities well-known in Provence and NW Sardinia (Bigi et al., 1992; Filigheddu & Oggiano, 1984; Mameli et al., 2007; Philip & Allemann, 1982; Yu et al., 2022).

The 130° CW Peloritan rotation turns out to be completely different from the 160° post-late Jurassic CCW rotation documented on NE Calabria by Siravo et al. (2022). This is unexpected, as the Calabro-Peloritan block has been mostly considered a unique terrane undergoing a semi rigid drift (Alvarez et al., 1974; Amodio-Morelli et al., 1976; Bonardi et al., 2001; Bouillin et al., 1987; Cifelli et al., 2007; Cirrincione et al., 2012, 2015; Faccenna et al., 1997, 2001; Malinverno & Ryan, 1986; Mattei et al., 2002). On the other hand, paleomagnetism reveals that Calabria and the Peloritan Mts. must be viewed as distinct terranes undergoing markedly different rotation-drift histories. The 160° CCW rotation of Calabria has been considered to represent the sum of several events: (a) 30° Early Cretaceous (150-120 Ma) “Greater Iberia” rotation, (b) 30° Oligo-Miocene (30-21 Ma) South Sardinia rotation during Liguro-Provencal Basin rifting, (c) 60° early Miocene (21-15 Ma) rotation along with whole Corsica-Sardinia microplate, and (d) local 40° block rotation related to Early Cretaceous left-lateral shear along Alpine Tethys (Siravo et al., 2022, 2023). Thus, we propose a new evolutionary model in which South Sardinia and Calabria rotated 90° CCW from 30 to 15 Ma on the northern limb of a Paleo Apennine-Maghrebide Arc that likely developed above the subduction of an Alpine Tethys oceanic embayment (Figures 9a and 9b). The southern CW rotating limb likely being along the Greater and Lesser Kabylies blocks, where however no paleomagnetic data have been obtained so far. The lack of the South Sardinia-Calabria CCW rotation fingerprint implies that the Peloritan terrane lied S of the CCW rotating system, likely at the non-rotational apex of the Oligo-Miocene orogenic salient. Thrust fronts of the external Peloritan nappes show a WNW trend and SSW-directed orogenic vergence (Figure 6g; Somma et al., 2005; Lentini & Carbone, 2014), implying that when back-rotated considering the 130° CW late Miocene rotation they formed roughly N-S—E verging—thrust fronts. Such direction differs from the NE trend that is commonly assumed for the Oligocene-early Miocene Alpine chain (Figure 9a), possibly indicating local Peloritan orogenic directions different than regional Alpine trends along a former salient apex. Fragmentation and disruption of the originally continuous accretionary front start to occur at this time as observed by relict strike-slip faults in the Ligurian Alps (Manna et al., 2023). Afterward, since late Miocene (∼12 Ma), the Sicilian Maghrebides and the overlying Peloritan terrane rotated 130° CW, representing the southern limb of a Neo Apennine-Maghrebide orogenic salient forming around the Tyrrhenian back-arc basin (Figures 9b and 9c). This reconstruction implies an apparent kinematic conundrum, as when back rotated the Peloritan terrane lies E of Sardinia, at odds with the lack of a CCW “Sardinian” rotation fingerprint in the Peloritan rocks. However, Sardinia amalgamated to Europe since 16–15 Ma, after the end of its CCW rotation, whereas the Peloritan block was incorporated in the African margin in mid Burdigalian (early Miocene) times, at 18–17 Ma. The early Miocene to present Africa-Europe convergence at S Tyrrhenian coordinates is ca. 1 cm/yr NNW directed (Jolivet & Faccenna, 2000), translating into a ca. 150 km NNW displacement of the Peloritan Mts. with respect to Sardinia after early Miocene. Therefore, before ∼15 Ma, the Peloritan terrane lied SE of Sardinia, at the apex of the Paleo Apennine Maghrebide Arc whose northern limb—including S Sardinia and Calabria—had previously undergone the 90° CCW rotation (Figure 9a).

Figure 9

Evolutionary model of the central western Mediterranean domain from Late Aquitanian to present day. The subduction and roll-back of an Alpine Tethys embayment (a) determined from 21 to 15 Ma (b) the spreading of the Liguro-Provencal (Alboran) back-arc basin and the CCW (CW?) rotation of Corsica-Sardinia microplate and Calabria (Kabylies) terranes along the limbs of the Paleo Apennine-Maghrebide Arc. The Peloritan terrane drifted SE-ward at the non-rotation apex of the orogenic salient. c. From ∼12 Ma to present the further roll-back of the Ionian Ocean induced the spreading of the Tyrrhenian back-arc basin and the CCW (CW) rotation of the southern Apennines (Sicilian Maghrebides) orogens, along the limbs of the Neo Apennine-Maghrebides Arc. Calabria drifted ESE-ward at the non-rotation apex of the newer orogenic salient, and eventually underwent a 20° CW rotation between 2 and 1 Ma.

The question arises as to why such older orogenic salient formed in Oligo-Miocene times. The apex of the Neo Apennine-Maghrebide salient formed clearly in correspondence of the oceanic Ionian Sea embayment—a relict of the Permo-Triassic Neo-Tethys—undergoing rapid subduction and roll-back. Thus, the apex of Paleo Apennine-Maghrebide salient likely formed above a more westerly embayment made by Alpine, and possibly also Neo-Tethys, oceanic crust. Recent works in fact showed that Permo-Triassic Neo-Tethys branches developed inside NW Pangea, even reaching Iberia (Angrand et al., 2020). The Alpine/Neo Tethys and paleo-Ionian oceanic embayments undergoing progressive subduction, and guiding the formation of the Paleo and Neo Apennine-Maghrebide Arcs, may have been originally coaxial and WNW-directed. Progressive N-S Africa Europe convergence broke embayment co-axiality, and implied that post-10 Ma Ionian roll-back and Neo Apennine-Maghrebide salient apex formed ahead the northern limb of the older 30–15 Ma Paleo-salient (Figure 9).

The boundary between the CW and CCW rotating Calabro-Peloritan domains is speculative, as the Calabrian results by Siravo et al. (2022) were obtained on the N Sila Mts. (northern Calabria), at more than 200 km far from the Peloritan nappes studied by us (Figure 1). E-W to NE-SW (in present-day coordinates) and variable kinematics transversal faults were advocated on Calabria (Cirrincione et al., 2015; Ortolano et al., 2013), and these could surely represent the boundary between the Calabrian and Peloritan terrains. However, it is likely that the different kinematics of the two blocks was driven by different lower plate nature, that is, thin (11–17 km) and dense oceanic crust of the Ionian Sea undergoing efficient subduction and enabling free SE-ward drift of Calabria, versus thick (30–40 km; e.g. Faccenna et al., 2014) continental crust of Sicily forming a foreland obstacle to the Peloritan block advance. Thus, it is likely that the so far unrecognized boundary between the two terranes falls somewhere between the Aspromonte Mts. (southern Calabria) and Peloritan Mts. (Figure 1), both characterized by strongly cataclastic high-grade metamorphic and igneous rocks hiding even major fault traces.

The excess 40° CCW rotation of Calabria with respect to Sardinian rotation was interpreted by Siravo et al. (2022, 2023) as a local block rotation due to Early Cretaceous left-lateral shear along Alpine Tethys. Siravo et al. (2022) also suggested that such tectonics yielded the Early Cretaceous turbidites of the Mt. Soro Fm. that are tectonically sandwiched between the Peloritan block and the Sicilian Maghrebides. Admitting that the Siravo et al. (2022) hypothesis is valid, there is no evidence of such hypothesized CCW block rotation in the external Peloritan Mts (and we lack paleomagnetic data from the Mt. Soro Fm.). However, it must be considered that block rotations related to strike-slip tectonics fade out at few km (maximum 20–30 km, e.g. Sonder et al., 1994; Speranza et al., 2018; Siravo et al., 2020) from the main shear zone. Conversely, during Early Cretaceous, the paleogeographic location of the Peloritan crust was certainly hundreds of km far from the basin where Mt. Soro turbidites deposited. Thus, the Peloritan crust represented a fragment of Greater Iberia drifting Eeastward during Early Cretaceous, whereas the Mt. Soro turbidites deposited in the inner and deeper troughs of the Alpine Tethys (Figure 2a).

8 Conclusions

Paleomagnetic data from 14 Jurassic-Oligocene sites of the Peloritan terrane retaining a primary magnetization show that:

1. The significant difference between CW rotation values measured in the Jurassic Ammonitico Rosso (99° ± 12°) and upper Cretaceous-Eocene Scaglia sediments (131° ± 15°) imply an Early Cretaceous 30° CCW rotation that matches in sign, magnitude, and timing, the Iberia rotation occurring during Bay of Biscay opening. Thus, paleomagnetic data from the Peloritan terrane strengthen the recent hypothesis by Siravo et al. (2023) that—prior to 30 Ma fragmentation—Iberia, Balearic Islands, S Sardinia, and the AlKaPeCa blocks formed the “Greater Iberia” plate.

2. Undistinguishable CW rotations measured in upper Cretaceous-Eocene (131° ± 15°) and upper Oligocene sediments (138° ± 12) resting above external and internal-intermediate nappes (respectively) imply that the Peloritan terrane rotated ∼130° CW as a whole. This rotation is the same for magnitude and sign as the post-Eocene rotation documented in the internal Panormide and Imerese nappes of the Maghrebide chain of W Sicily.

3. As the Peloritan terrane was stacked over the Sicilian Maghrebides in mid Burdigalian (18-17 Ma), we suggest that the Peloritan terrane was passively carried on top of rotating Maghrebide thrust fronts since Serravallian (∼12 Ma) times. Thus a “tectonic layering” characterized the Peloritan terrane during late Miocene, as extensional tectonics occurred at shallow crust levels while synchronous deep Maghrebian thrust sheets passively carried (and rotated) the whole orogenic stack.

4. The Peloritan (∼130° CW) and Calabria (∼160° CCW; Siravo et al., 2022) rotations are completely different. Thus, the Peloritan Mts. and Calabria must be considered as terranes undergoing completely different drift and rotation histories, at odds with the traditional view of a single and semi-rigid “Calabro-Peloritan block.”

5. Considering also paleomagnetic data from Calabria and Sardinia (Siravo et al., 2022, 2023) we conclude that Calabria lied just E of South Sardinia, participating to its 90° Oligocene-early Miocene (30-15 Ma) CCW rotation-whereas the Peloritan terrane—lacking the Sardinian CCW rotation fingerprint—lied further south, at the non-rotational apex of a 30-15 Ma “Paleo Apennine-Maghrebide Arc.” Thus, Sardinia and Calabria represented the northern CCW rotating limb of such a curved orogen, the Peloritan block lied at the non-rotational salient apex, and the Kabyle blocks must have formed the (CW rotating?) SW limb.

6. Since late Miocene (∼12 Ma), the Paleo Apennine-Maghrebide Arc was in turn strongly bent, and a new salient formed whose limb(s)/apex did not coincide with the former ones. Considering the Paleo salient's northern limb, Calabria underwent an almost non-rotational ESE-ward directed drift above rolling back Ionian oceanic crust and became the apex of the “Neo Apennine-Maghrebide” orogenic salient. Conversely, at the Paleo-Arc apex, the Peloritan terrane underwent a 130° CW thrust-related rotation carried on top of internal Maghrebian nappes, being thus incorporated in the SW limb of the younger salient.

Our work—along with recent paleomagnetic data from Calabria and Sardinia (Siravo et al., 2022, 2023)—shows that the Oligo-Miocene dispersal of the AlKaPeCa blocks in the W Mediterranean realm was more complex than previously thought.

Acknowledgments

We thank Maria Pia Curasì for welcoming us and allowing our sampling around San Marco d’Alunzio. Discussions with Rosanna Maniscalco on Maghrebian geology are appreciated. Lilla Spagnuolo helped in the field and in the laboratory measurements. Filippo Calì Quaglia, Francesca D’Ajello Caracciolo, and Alessandro Pignatelli, helped to perform common mean direction tests. Careful reviews by P. Calvin and M. Ozkaptan helped to clarify magnetization acquisition and rotation issues. Thanks also to Tectonics Editor (L. Jolivet) and Associate Editor (J. Geissman) for carefully evaluating our work. Funding was provided by INGV—Istituto Nazionale di Geofisica e Vulcanologia (Italy). The view of the post-Oligocene dispersal of AlKaPeCa blocks was first clearly formulated and discussed by Walter Alvarez and colleagues in 1974, although the first images of a similar paleogeographic setting incredibly dates back to the visionary pictures drawn by Emile Argand in the manuscript “La tectonique de l’Asie,” published in 1924, exactly 100 years ago. We acknowledge sitting on the shoulders of such grand giants. Open access publishing facilitated by Istituto Nazionale di Geofisica e Vulcanologia, as part of the Wiley - CRUI-CARE agreement.

Open Research

Data Availability Statement

Original data set reported in the study is available at https://doi.org/10.5281/zenodo.8411189 (Siravo & Speranza, 2023).