NE Sicily Research Articles

Using drone imagery and group field activities for an in-depth investigation of the vascular flora: a case study in the Rocca di Novara Massif (NE Sicily, Italy)

Using drone imagery and group field activities for an in-depth investigation of the vascular flora: a case study in the Rocca di Novara Massif (NE Sicily, Italy)

The recent evolution of the salt marsh ‘Pantano Grande’ (NE Sicily, Italy): interplay between natural and human activity over the last 3700 years

AbstractCombined natural processes and human activities shaped the late Holocene landscape history in many Mediterranean regions. This is especially true with areas subjected to specific human interest, such as coastal areas morphologically suitable to the establishment of harbours. Here, we test the hypothesis on the location of the Roman harbour Portus Trajectus in Peloro Cape (NE Sicily, Italy) and describe the evolution of the area over the last 3700 years through lithostratigraphic, geochemical, meiofauna and microfossil analyses performed on a new sediment core recovered from the coastal salt marsh Pantano Grande (aka Lago di Ganzirri). The age–depth model was developed on radiocarbon dates and geochemical fingerprinting of two tephra layers. Results indicate that the area underwent dramatic changes ca. 650 bce. The anthropogenic impact of Greek colonies may have contributed to modifying the coastal environment of Peloro Cape due to their widespread impact on natural resources. This happened at many localities in the Mediterranean, indicating the magnitude of impact of the Greek colonies over the landscape. According to our results, it is unlikely that the current Pantano Grande basin was used as a harbour in Roman times, although the presence of a harbour in the nearby Pantano Piccolo marsh cannot be excluded. Pantano Grande had been isolated from the sea for more than 2000 years. Human intervention in the 19th century halted that isolation and provided the background for the ecological, economic and social functions the salt marsh performs today.

Alvania acidasp. nov., a new late Quaternary gastropod adapted to the shallow‐marine CO2seep of Vulcano Island

ABSTRACTSubmarine CO2emissions are a recent (probably younger than about 5 ka) expression of volcanism at Vulcano Island (off NE Sicily), a Mediterranean natural laboratory for the study of ocean acidification. An impoverished molluskan association is known from the naturally acidified waters of Vulcano, at Levante Bay, where pH drops to 5.64. Here we describe a new gastropod,Alvania acidasp. nov., living in the bay, and found at the nearby site of Capo Milazzo (NE coast of Sicily) within a Late Pleistocene paleocommunity related to vegetated bottoms. The study species underwent a habitat change during its short evolutionary history, resulting in the recent adaptation to the CO2seep at Vulcano. Similarly to the gastropodsTritia corniculumandT. neriteafrom the same seep,A. acidawas up to 24% smaller than fossil shells from Milazzo, showing a further probable case of adaptation to high‐CO2waters through dwarfing. The new species shows distinctive features: an inflated shell; very convex, axially ribbed whorls; weak spiral cords. Because of its current distribution, limited to Levante Bay, and anthropogenic pressure from tourism affecting the site,A. acidadeserves protection.

Structural geology of the eastern termination of the Mt. Kumeta-Alcantara line (NE sicily, Italy)

ABSTRACT In this paper we show data from new detailed geological-structural field surveys, integrated with preliminary photogrammetric analysis, presented in a 1:10,000 scale geological map. The field-based investigations covered an area of about 60-km2, located at the southern termination of the Calabrian Forearc, in NE Sicily (Italy), at the intersection of two key regional-scale fault systems. These are represented by the Peloritani Sole-Thrust, along which the Kabilo-Calabride orogenic edifice overthrusted onto the Apenninic-Maghrebian Chain, and the Mt. Kumeta-Alcantara Line, which played a key role in the post-Oligocene evolution of the Nubia–Eurasia converging margin. The collected data permitted the recognition of a new terrigenous stratigraphic unit, the Malvagna Flysch, and the acquisition of updated structural information useful to better understand the kinematics of the easternmost portion of the Mt. Kumeta-Alcantara Line. The geological map provides new insights for the reconstruction of the geodynamic evolution of this sector of the Calabrian Forearc.

A new species within the Centaureabusambarensis complex (Asteraceae, Cardueae) from Sicily.

The Centaureabusambarensis group is made up by eight species endemic to Sicily. We statistically evaluated a population found on the Nebrodi Mountain (NE Sicily) to verify if the observed morphological differences with the already known taxa justified the description of a new one. It resulted in being sufficiently distinct to deserve recognition at the species level. Centaureavaldemonensis, a new species endemic to Sicily is described and illustrated here. It is confined to the Nebrodi Mountains (NE Sicily). The distinction of this taxon from the others belonging to the C.busambarensis complex has been supported with the aid of statistical analyses on morphological characters. The differences with the related taxa are discussed.

First contribution to the ethnobotanical knowledge in the Peloritani Mounts (NE Sicily)

This paper presents the results of an ethnobotanical survey carried out in the Peloritani Mounts (NE Sicily). This investigation aims to illustrate the first record known of the traditional uses of plants in this territory through the case study of a small rural suburb named Tipoldo (Messina). The data were collected from 20 informants over the age of 66, who were mainly farmers and shepherds, and were analyzed using two quantitative ethnobotanical indicators. For each plant was reported the Latin name, life form, vernacular name, parts used, ethnobotany category, claimed uses, status, and their relative indexes. Based on semi-structured interviews carried out between February 2017 and May 2018, a listing was compiled of 126 wild plants belonging to 51 families, the most predominant being Asteraceae (19 species) and Fabaceae (15 species). The most common ethnobotanical uses reported are medicinal (30%) and agropastoral use (19%). Among the preparation methods indicated, leaves (39%) were the most commonly used parts of the plants, while the species most mentioned in connection with ethnobotanical applied indexes were: Crepis vesicaria, Dittrichia graveolens, Hypochaeris radicata, Salvia Rosmarinus and Clinopodium nepeta. These practices are presently performed only by a few elderly people, who rely on plants solely for a few activities. Furthermore, ethnobotanical studies are fundamental to clear up the knowledge on the traditional plant uses that are still current in this part of Sicily, to preserve this cultural heritage for future generations.

First record of Sida rhombifolia L. (Malvaceae) for Italian flora

Sida rhombifolia L. (Malvaceae) has been reported for the first time in Italy. This species with a Paleotropics geographic origin represents a new invasive alien species in the flora of Italy. It was already reported in several European countries as invasive species, but this plant is also known for its medicinal properties in many areas of the world. The species was found in the anthropic environments of Sicily. In particular, the study area is localized in the Peloritani Mounts (NE Sicily) where the species was discovered in five stands. Our new discovery confirmed the role of anthropic activities have had in the alien species invasion in Italy. Diagnostic features, ecological and geographic data are provided. From a phytosociological viewpoint, this plant characterizes a plant community that includes various nitrophilous species such as Digitaria sanguinalis (L.) Scop., Eleusine indica (L.) Gaertn. and Sorghum halepense (L.) Pers. Moreover, invasiveness and impacts associated to this species were assessed by using EPPO prioritization protocol. The specimens were deposited in the herbaria of Catania and Messina University.

Bottom current-controlled Quaternary sedimentation at the foot of the Malta Escarpment (Ionian Basin, Mediterranean)

A better understanding of the evolution of bottom current circulation and associated deposits is significant for many applications including paleoclimatology and geological hazard. Besides the large contourite drifts, bottom currents may generate fields of large sediment waves that, depending on their height and velocity of migration, may pose severe risk for infrastructures. Conversely, the time span of their paleoceanographic record is generally relatively short. We use bathymetry data, sub-bottom and seismic reflection profiles and legacy oceanographic data to analyze the sediment waves occurring in a deep environment (from 2400 to 3800 m water depth at the foot of the Malta Escarpment in the Mediterranean Sea) to understand their evolution in time, their significance for paleoceanography, and their relation to present day hydrographic conditions. In the absence of direct stratigraphic information, we use the information from nearby studies and from ODP Site 964 and DSDP Site 374 to constrain the age of the sedimentary successions. We discover that these waves (about 2.5 km in wavelength, 50 m in height, with crest sub-perpendicular to the continental slope trend) have been steadily growing and migrating northward since about 500 ka, although an irregular growth and unsteady migration is distinguishable since about 1800 ka. The waves are generated by predominantly alongslope southward flowing bottom currents compatible with modern hydraulic conditions (mean flow speed of ~5 cm s−1, peaks of 15 cm s−1). The rate of crest migration (~ 2.0–3.2 mm a−1) and the average sedimentation rate (0.64–0.69 mm a−1) are unusually high for deep sea environments away from turbidity currents paths. We infer that the steady development of sediment waves is produced by a drastic increase in sediment input to the Ionian Basin resulting from the tectonic uplift in NE Sicily and Calabria and the onset of a relatively steady, low energy bottom current regime following the Mid-Pleistocene Transition. We attempt to extract information on orbital cyclicity preserved in the seismic record from the power spectra of virtual seismic traces from the well preserved succession of 5 visually discernible, regularly spaced sub-units consisting of alternation of high-amplitude and low-reflectivity packages within the last 500 ka. Peaks in the power spectra can be identified around orbital obliquity and precession periodicities, while eccentricity appears not to be recorded. We discuss the results of seismic cyclicity analysis relative to uncertainties of stratigraphic and petrophysical constraints. The sediment waves along the foot of the Malta escarpment are an excellent candidate for the extraction of a long, continuous and high resolution sedimentary record of the paleo circulation changes and climate cycles in the Mediterranean Sea since about 500 ka.

Isotopic evolution of prehistoric magma sources of Mt. Etna, Sicily: Insights from the Valle Del Bove

Mount Etna in NE Sicily occupies an unusual tectonic position in the convergence zone between the African and Eurasian plates, near the Quaternary subduction-related Aeolian arc and above the down-going Ionian oceanic slab. Magmatic evolution broadly involves a transition from an early tholeiitic phase (~ 500 ka) to the current alkaline phase. Most geochemical investigations have focussed on either historic (> 130-years old) or recent (< 130-years old) eruptions of Mt. Etna or on the ancient basal lavas (ca. 500 ka). In this study, we have analysed and modelled the petrogenesis of alkalic lavas from the southern wall of the Valle del Bove, which represent a time span of Mt. Etna’s prehistoric magmatic activity from ~ 85 to ~ 4 ka. They exhibit geochemical variations that distinguish them as six separate lithostratigraphic and volcanic units. Isotopic data (143Nd/144Nd = 0.51283–0.51291; 87Sr/86Sr = 0.70332–0.70363; 176Hf/177Hf = 0.28288–0.28298; 206Pb/204Pb = 19.76–20.03) indicate changes in the magma source during the ~ 80 kyr of activity that do not follow the previously observed temporal trend. The oldest analysed Valle del Bove unit (Salifizio-1) erupted basaltic trachyandesites with variations in 143Nd/144Nd and 87Sr/86Sr ratios indicating a magma source remarkably similar to that of recent Etna eruptions, while four of the five subsequent units have isotopic compositions resembling those of historic Etna magmas. All five magma batches are considered to be derived from melting of a mixture of spinel lherzolite and pyroxenite (± garnet). In contrast, the sixth unit, the main Piano Provenzana formation (~ 42–30 ka), includes the most evolved trachyandesitic lavas (58–62 wt% SiO2) and exhibits notably lower 176Hf/177Hf, 143Nd/144Nd, and 206Pb/204Pb ratios than the other prehistoric Valle del Bove units. This isotopic signature has not yet been observed in any other samples from Mt. Etna and we suggest that the parental melts of the trachyandesites were derived predominantly from ancient pyroxenite in the mantle source of Etna.

Benthic Foraminiferal Response to Sedimentary Processes in a Prodeltaic Environment: The Gulf of Patti Case Study (Southeastern Tyrrhenian Sea)

Analyses of benthic foraminiferal assemblages were carried out on sediment samples collected in the Gulf of Patti (NE Sicily, Tyrrhenian Sea), where high sedimentation rates in front of the Mazzarrà River led to the growth of a prodelta. The frequency of riverine sedimentary fluxes is testified by the widespread occurrence of erosional and depositional bedforms indicative of high-energy processes on the prodelta slope.The frequency of riverine sedimentary fluxes suggests the widespread occurrence of erosional and depositional bedforms indicative of high-energy processes on the prodelta slope. The study aimed to assess the spatial distribution of benthic foraminiferal assemblages and sediment grain size along different sectors of this prodelta to define any relationship between the foraminiferal assemblages, the environmental gradients and the sedimentary processes. In particular, we focused on the role of the highly energetic impulsive torrential inputs that dominate the depositional environment and likely affect food supply and its control on the foraminiferal density and biodiversity. The dominance of opportunistic agglutinated taxa associated with hyaline eutrophic species is a distinctive character likely related to organic matter enrichment and physical disturbance associated with inputs from torrential rivers.

&lt;strong&gt;Taxonomic remarks on the &lt;em&gt;Centaurea aeolica&lt;/em&gt; (&lt;em&gt;Asteraceae&lt;/em&gt;) species complex&lt;/strong&gt;

In the course of a taxonomical revision of Centaurea aeolica and the closely related C. pandataria, species confined to the Aeolian Archipelago (N Sicily) and Ventotene island (Pontian Archipelago, Latium) respectively, we describe a new species, named C. phalacrica, occurring on coastal metamorphic rocks near Messina (NE Sicily). These three species, well differentiated in several features, are examined from morphological, nomenclatural, chorological, and ecological points of view. For each species, a detailed iconography, consideration on their conservation status and identification keys are provided too. The lectotype of C. pandataria kept in the Florence Herbarium (FI) is designated.

Metasedimentary Metatexites with Trondhjemitic Leucosomes from NE Sicily: Another Example of Prograde Water-fluxed Melting in Collisional Belts

Trondhjemitic leucosomes, hosted in late Variscan metasedimentary migmatites from the upper amphibolite-facies basement of the north-eastern Peloritani Mountains (southern Italy), have petrographic and geochemical features consistent with their origin as near-pure melts derived from in situ water-fluxed melting of their paragneiss host-rocks. Comparison with results of experimental melting and thermodynamic modelling of metasedimentary rocks suggests a dominant derivation of the leucosomes by melting, at c. 1.0 GPa and 700 °C, metagreywackes with a high pelitic content. Migmatization likely began at the thickening-related baric peak, or during the early post-collisional exhumation stages. A subsequent heating stage following the decompression and solidification of the leucosomes triggered a second melting stage, involving muscovite and biotite incongruent breakdown, with an associated production of peritectic sillimanite and garnet, and small leucogranitic patches within the trondhjemitic leucosomes. These melting events can be framed in the typical clockwise P-T-(t) evolution of the Variscan Belt in western and southern Europe, depicting collision-related thickening followed by widespread migmatization, starting close to the baric peak at c. 345 Ma and continuing during exhumation, with a duration of c. 25 Ma, up to c. 320 Ma.

From sepulchre to butchery-cooking: Facies analysis, taphonomy and stratigraphy of the Upper Palaeolithic post burial layer from the San Teodoro Cave (NE Sicily) reveal change in the use of the site

The San Teodoro Cave is considered the most significant witness of the first, Epigravettian, human colonization of Sicily from the Italian continent. Furthermore the site is a paradigmatic horizon in the Pleistocene faunal record, demonstrating a progressive transition from mega faunas to smaller-sized, Boreal, faunas. The site has been repeatedly studied and excavated, with different aims and approaches, leading to an interpretation of Epigravettian burial site and daily attendance. Here we propose a reappraisal of the study of the stratigraphy of the site, and in particular of the bone-rich layer (PAL) accumulated over the red ochre layer that apparently sealed all the different burials, with the exception of one. The study has been conducted starting from a new, consistent collection of materials from the PAL layer previously identified by Bonfiglio and co-authors, and moved from the morphological and microscopical identification of faunal remains and their taphonomy, to the accurate geological, petrographical and pedological definition of the sediments by stereomicroscope (SM), polarized light microscope (PLM) and X-Ray diffractometry (XRD) analyses.We propose the first 14C AMS dating of the layer PAL, performed on a Bos primigenius sample that has been dated to 12624 ± 59 BC, 15224–14708 cal yr BP. This date does not differ much from the dates obtained with analogous methodology on buried human remains. Despite the difficulty of a reconstruction of biological times and human behaviours that are not chronologically traceable, we can nonetheless state that the site had at least two main moments of attendance in the late Upper Palaeolithic: one linked to burials, excavated in a cave still sporadically visited by humans, and a second period of intense attendance, industrial production of quartz arenite lithics and rare flint, intensive slaughter of late-glacial Boreal fauna and presence of many combustion residues.

Widespread mass-wasting processes off NE Sicily (Italy): insights from morpho-bathymetric analysis

Abstract The NE Sicilian continental margin is largely affected by canyons and related landslide scars. Two main types of submarine canyons are recognizable: the first type carves the shelf up to depths &lt;20 m, a few hundred metres from the coast, acting as a main collector for sediments transported by hyperpycnal flows and/or littoral drift. These canyons mostly have a V-shaped cross-section and are characterized by a strong axial incision, where a network of dendritic gullies carving the canyon flanks converges. The second type of canyon occurs where the shelf is wider, hindering the direct connection between the subaerial and submarine drainage system. This setting exhibits canyon heads mostly confined to the shelf break, characterized by a weaker axial incision of the canyon and U-shaped cross-section. A total of 280 landslide scars are recognized in the study area and these are divided into three groups according to their morphology and location. A morphometric analysis of these scars is performed to investigate which parameters might be key factors in controlling instability processes and how they correlate with each other. We also try to assess the possible tsunamigenic potential associated with these landslide events by coupling the morphometric analysis with semi-empirical relationships available in the literature.

Insights on the Capo d'Orlando flysch (NE Sicily) by means of geomechanics and sedimentology

A multidisciplinary integrated approach for the study of heterogeneous rock masses is presented herein with the aim of providing a characterization of one of the widest flysch formations of northeastern Sicily. The Capo d'Orlando Flysch is indeed affected by a geotechnical heterogeneity arising from the alternation of sandstone banks and siltstone layers occurring in different proportions and showing peculiar features. This is the main responsible of the uneven mechanical strength offered by these different lithological compartments and deserves an in-depth study. To this purpose, an integrated sedimentological-geomechanical study is the focus of this research, which was initially carried out through rock mass surveys aimed at recognizing the different facies associations and their distribution along selected outcrops. Sedimentological logs were followed by rock mass geomechanical surveys for the assessment of the quality of the rock and its discontinuities. All these elements concurred in the definition of the Geological Strength Index, which is preparatory for the estimation of the main mechanical properties of the rock mass through the Hoek and Brown failure criterion. Results show that the lithological compartments occurring within flysch rock masses strongly condition their mechanical attitude. In fact, sandstone portions behave as massive/fractured rock mass characterized by specific geomechanical properties, which are lowered by the presence of siltstone layers. For this reason, the definition of the facies associations (F.A.) affecting the rock mass, along with their geomechanical characterization, is a useful integrated activity to avoid overestimating or underestimating the mechanical attitude of flysch rock masses, especially when engineering geological works have to be designed.

Automated SEM‐EDS pottery classification based on minero‐chemical quantitative parameters: An application on ancient Greek pottery from Adrano (NE Sicily, Italy)

A new SEM‐EDS procedure for ancient ceramic classification, based on the automated acquisition and the semiautomated processing of multi‐elemental X‐ray maps, is described. Based on the detection of each aplastic inclusion, the procedure allows to simultaneously obtain a quantitative evaluation of both the inclusion mineral–chemical composition and the ceramic matrix chemical composition. The two data sets can individually or jointly be subjected to statistical methods. The proposed protocol was applied on a set of 22 samples of black glaze pottery from Adrano (north‐eastern Sicily), Hellenistic age (4th to 2nd centuries B.C.). Two main groups emerged from the application of the procedure, mainly distinguished for their quartz–feldspars versus calcium–aluminosilicate relative abundance as the inclusion mineral–chemical composition is concerned and for their matrix SiO2 versus CaO. The classification based on the inclusion mineral–chemical data obtained with the proposed method mirrors the results from the traditional OM observation, but when the two data sets are simultaneously considered, a subtler differentiation is observed with the separation of one of the groups in two subgroups, allowing to refine the partition.

Poly-Orogenic Melting of Metasedimentary Crust From a Granite Geochemistry and Inherited Zircon Perspective (Southern Calabria-Peloritani Orogen, Italy)

Inherited zircon ages and geochemical features of late Cadomian and late Variscan granitoids from the north-eastern Peloritani Mountains (NE Sicily) and the western Aspromonte Massif (SW Calabria) shed new light on the sources and processes involved in poly-orogenic granitoid magmatism. The two groups of strongly peraluminous granitoids have similarities in trace element abundance patterns and Sr and Nd isotopic compositions consistent with both being derived from crustal sources, possibly with a minor contribution from mantle-related components. Comparison of the granite compositions with those of experimental melts derived from various metaigneous and metasedimentary sources indicates that both groups of granitoids originated exclusively from different degrees of melting of similar greywacke-dominated turbidite. Abundant inherited zircon cores from representative samples of metamorphosed late Cadomian (545 ± 5 Ma) granite and late Variscan (300 ± 4 Ma) leucogranodiorite have the same range of U-Pb ages, from Early Paleoproterozoic to latest Neoproterozoic, with main age clusters at ~ 0.55 and ~ 0.63 Ga, and minor age clusters at ~ 0.95 and ~ 2.5 Ga. The pattern of detrital zircon ages from a paragneiss, host rock to the late Cadomian granite, is the same, indicating, in conjunction with the geochemistry, that both granites originated by partial melting of deeper crustal equivalents of those paragneisses. The same crustal sequence melted during successive orogenies under different thermal regimes and in different post-collisional tectonic settings, giving rise to granitoid associations with different ages and geochemical features largely reflecting the melting conditions. On the other hand, the zircon inheritance patterns and specific chemical features of S-type granitoids reflect the nature of their crustal magma sources, independently from the effects of the thermal regime or tectonic setting at the time of magmatism.

Biogenic habitat shifts under long-term ocean acidification show nonlinear community responses and unbalanced functions of associated invertebrates

Experiments have shown that increasing dissolved CO2 concentrations (i.e. Ocean Acidification, OA) in marine ecosystems may act as nutrient for primary producers (e.g. fleshy algae) or a stressor for calcifying species (e.g., coralline algae, corals, molluscs). For the first time, rapid habitat dominance shifts and altered competitive replacement from a reef-forming to a non-reef-forming biogenic habitat were documented over one-year exposure to low pH/high CO2 through a transplant experiment off Vulcano Island CO2 seeps (NE Sicily, Italy). Ocean acidification decreased vermetid reefs complexity via a reduction in the reef-building species density, boosted canopy macroalgae and led to changes in composition, structure and functional diversity of the associated benthic assemblages. OA effects on invertebrate richness and abundance were nonlinear, being maximal at intermediate complexity levels of vermetid reefs and canopy forming algae. Abundance of higher order consumers (e.g. carnivores, suspension feeders) decreased under elevated CO2 levels. Herbivores were non-linearly related to OA conditions, with increasing competitive release only of minor intertidal grazers (e.g. amphipods) under elevated CO2 levels.Our results support the dual role of CO2 (as a stressor and as a resource) in disrupting the state of rocky shore communities, and raise specific concerns about the future of intertidal reef ecosystem under increasing CO2 emissions. We contribute to inform predictions of the complex and nonlinear community effects of OA on biogenic habitats, but at the same time encourage the use of multiple natural CO2 gradients in providing quantitative data on changing community responses to long-term CO2 exposure.

Combining field data with infrared thermography and DInSAR surveys to evaluate the activity of landslides: the case study of Randazzo Landslide (NE Sicily)

Infrared thermography and DInSAR surveying methodologies have been integrated and compared to study the state and distribution of activity of one of the largest landslides of northeastern Sicily, Italy, which is characterized by a slow retrogressive evolution. The Randazzo Landslide was triggered by heavy rainfalls in 1996 and its activity caused the disruption of a strategic transportation corridor, along with the formation of a landslide dam in the Alcantara Valley. After more than 20 years, the slope is still affected by instability and worrying signs of reactivations (e.g., deformation and cracking of road pavement) were surveyed in the field. The application of infrared thermography during the landslide survey allowed detecting peculiar features according to the different thermal pattern of the elements occurring along the slope. In particular, areas with different surface temperature were associated to vegetated spots, steep portions, bare sectors, and contact between different lithologies. Incipient portions and ancient landslide bodies were located, proving the utility of this experimental approach to the surveying of unstable slopes. Information on the entity, in terms of velocity, of the recent landslide displacements were provided by a DInSAR monitoring, which allowed ascertaining the presence of movements affecting several sectors of the landslide, mainly matching with the areas highlighted by thermal images. Achieved outcomes represent a scientifically relevant datum providing important information on the surveyed landslide from the risk management point of view and proving the utility of integrating infrared thermography and DInSAR methodologies for the study of complex movements.

The Relationships Between Regional Quaternary Uplift, Deformation Across Active Normal Faults, and Historical Seismicity in the Upper Plate of Subduction Zones: The Capo D'Orlando Fault, NE Sicily

AbstractIn order to investigate the deformation within the upper plate of the Calabrian subduction zone, we have mapped and modeled a sequence of Late Quaternary paleoshorelines tectonically deformed by the Capo D'Orlando normal fault, NE Sicily, which forms part of the actively deforming Calabrian Arc. In addition to the 1908 Messina Strait earthquake (Mw7.1), this region has experienced damaging earthquakes, possibly on the Capo D'Orlando Fault; however, it is not considered by some to be a potential seismogenic source. Uplifted Quaternary paleoshorelines are preserved on the hangingwall of the Capo D'Orlando Fault, indicating that hangingwall subsidence is counteracted by regional uplift, likely because of deformation associated with subduction/collision. We attempt to constrain the relationship between regional uplift, crustal extensional processes, and historical seismicity, and we quantify both the normal and regional deformation signals. We report uplift variations along the strike of the fault and use a synchronous correlation technique to assign ages to paleoshorelines, facilitating calculation of uplift rates and the fault throw rate. Uplift rates in the hangingwall increase from 0.4 mm/year in the center of the fault to 0.89 mm/year beyond its SW fault tip, suggesting 0.5 mm/year of fault‐related subsidence, which implies a throw rate of 0.63 ± 0.02 mm/year, and significant seismic hazard. Overall, we emphasize that upper plate extension and related vertical motions complicate the process of deriving information on the subduction/collision process, such as coupling and slip distribution on the subduction interface, parameters that are commonly inferred for other subduction zones without considering upper plate deformation.