Northern Calabria Research Articles

Structural style of Quaternary extension in the Crati Valley (Calabrian Arc): evidence in support of an east-dipping detachment fault

New geological field data, integrated with commercial seismic lines, allowed us to constrain the geometry and time-space evolution of the fault system that ruled the tectono-sedimentary evolution of the NS-striking Crati graben, in the axial portion of the northern Calabrian Arc.We highlight that this basin is controlled by a 60-km long east-dipping master fault, referred to as the Crati Graben Detachment Fault (CGDF).On the seismic sections, the CGDF appears as an east-dipping low-angle reflection reaching the surface along the eastern slope of the Catena Costiera Calabra. Its surface expression corresponds to an alignment of moderately-inclined (30° to 45°) left-stepping en-echelon faults.More to the East, a number of E- and W-dipping high-angle normal faults branch upward from the CGDF. Their reconstructed timing suggest that the westernmost faults are active since the Early Pleistocene and show a progressive eastward rejuvenation trend.The conversion to depth of a W-E oriented seismic section, crossing the entire Crati graben, highlights that the CGDF has a staircase geometry, with an average angle of 30°, and reaches a depth of 7-8 km below the east side of the basin. The evolutionary stages of the related fault system were reconstructed by restoring the section through the Move suite software (Midland Valley Exploration), in order to verify the kinematic consistency of our subsurface interpretation and estimate the amount of associate extension.Finally, the present activity and the possible seismogenic role of the CGDF is preliminarily discussed, by comparing the geometry of the extensional fault system with the available historical and seismological instrumental datasets.

Microbial-mediated pre-salt carbonate deposition during the Messinian salinity crisis (Calcare di Base fm., Southern Italy)

A multi-scale analysis of sedimentary carbonate facies and post-sedimentary diagenetic features of the Calcare di Base Formation, the precursor to evaporites in Upper Messinian successions of Northern Calabria and Central Sicily, has revealed their microbial bio-mediated origin. Massive to laminated microbial boundstones represent the most common sedimentary facies forming flat to low relief cm to m scale stromatolitic and thrombolitic bodies. The fabric of the micrite varies from peloidal to aphanitic, and almost always preserves filamentous bacteria which characterized the original microbial mat. The mat was dominated by sulphur-oxidizing bacteria belonging to the Thiotrichaceae, but there is evidence for a more complex community with sulphate- and/or nitrate-reducing bacteria, all being responsible for the mediation of the carbonate precipitation. Microbial boundstones are rich in pseudomorphs of Ca-sulphate and halite, which formed during the deposition of the microbial carbonate. Layers of primary gypsum are interbedded locally with carbonates suggesting the presence of restricted marine conditions. The stable O and C isotopic composition of the carbonates, that vary from dolomite to aragonite and calcite, suggests a complex interplay between arid to humid climatic changes, expressed cyclic interbedding of the carbonate with marl-marlstone. Later diagenetic events mainly consist of phreatic meteoric recrystallization and cementation. Although considered as diachronous, the microbial carbonates can be mapped out over a distance of more than 500 km across southern Italy; this indicates near-constant environmental conditions upon the central Mediterranean shelf at the beginning of the salinity crisis. Deposition of the extensive subaqueous microbial deposit that largely comprises the Calcare di Base is envisaged to have taken place across a shallow to moderate depth platform with local slopes into deeper water areas, where some resedimentation occurred.

Putting the Spotlight on Small Metal Age Pottery Scatters in Northern Calabria (Italy)

ABSTRACTThis paper presents the results of an in-depth multidisciplinary restudy of small Metal Age surface scatters recorded in earlier fieldwalking surveys in northern Calabria (Italy). Guided by a stratified sampling approach based on site types and topographic positions, high-resolution surface collections at the selected sites were combined with geophysical surveys, test pits, and soil studies to investigate both archaeological deposits and the site formation processes that have an effect on their detectability. This approach is shown to result in a better definition of archaeological ‘sites’, and to help fill in details of regional exploitation and settlement dynamics at the landscape scale. At this broader scale we are also able to model post-depositional processes and slope dynamics affecting the preservation of the archaeological record. With regard to methodology, our study has enabled the evaluation of diverse archaeological detection methods and the fine-tuning of field strategies for the study of Metal Age remains.

The Crati River Basin: geomorphological and stratigraphical data for the Plio–Quaternary evolution of northern Calabria, South Apennines, Italy

Abstract In this paper, we present the results of an integrated geomorphological and stratigraphical study carried out in the eastern side of the Crati River valley (northern Calabria, South Italy). This area is characterized by the occurrence of three order palaeosurfaces that, along with low-sloping palaeovalleys and structural landforms, are striking features of the landscape. The relationships between morpho-tectonic and sedimentary evolution of the Crati Basin has been assessed through sandstone detrital modes, morphostratigraphy and geomorphological correlation with adjacent areas. The two main unconformity surfaces that typify the Quaternary fill were correlated to different steps of landscape evolution. The presence of both erosional and depositional palaeosurfaces has been a useful marker for reconstructing sedimentary and morphogenetic events, and hence to detect drainage network evolution and changes in source sediment area. In particular, we recognized that the study area experienced, during the late Pliocene–Early Pleistocene a period of sub-aerial landscape modelling as suggested by low-sloping palaeovalleys and related fluvial deposits (1st Order Palaeosurface). At that time, the source of the detrital constituents of the PPS Unit sandstones was mainly from the Sila Massif. The onset of Coastal Range identification and uplift (Early Pleistocene) marks a change in the geomorphic scenario with tectonic driven stream incision and valley development along the eastern side of Coastal Range, along with the occurrence of depositional and erosional landsurfaces (2nd Order Palaeosurface) at footslopes. During this period, the Coastal Range and Sila Massif were the sources for the detrital constituents of the PlS Unit sandstones. The progressive uplift of Coastal Range during late Early Pleistocene and the marked backstepping of the depositional systems along the Sila footslope was accompanied by alternating phases of down-cutting and base-level stability resulting in the development of a step-like distributed 3rd Order Palaeosurface. The presence of dolostone in detrital modes is clear evidence of stream piracy phenomena of ancient palaeovalleys by the Crati valley-facing drainage network.

Broken speleothems reveal Holocene and Late Pleistocene paleoearthquakes in Northern Calabria, Italy

Two underground cavities in the Northern Calabria region, the Romito and the San Paolo caves, have been selected for speleoseismic analysis in order to provide a timeframe for paleoearthquakes which have shocked the cave sites and the surrounding area. The caves are positioned in a seismogenically active region, which has been struck by medium to large earthquakes in historical and pre-historic times. Moreover, frequent instrumentally measured small to moderate seismicity occurs in the area (M ≤ 5.6). We document damaged carbonate cave deposits, including collapsed and broken stalactites, in-situ severed stalagmites and stalactites, and collapsed bedrock ceilings. Samples were sawed in order to expose breakages and contacts within the laminae. Sixteen laminae, eight pairs of pre and post event laminae, were drilled for dating by the UraniumThorium disequilibrium technique. Three discrete events were defined by six of the speleoseismites to (I) 7.4–2.9 ka, (II) 9.7–8.2 ka, and (III) 28.4–27.4 ka. Two additional speleoseismites gave wide age brackets, but are confined to 65.7–18.6 ka, which overlaps with event III, but might represent additional events. The present speleoseismic work depicts a scenario of a minimum of three well-constrained strong shaking events in a time span of the past ∼28 ky, yielding a maximum recurrence interval of ∼9 ky. In 2012 the area was shaken by a Mw5.2 earthquake that apparently did not produced damage within the study cavities, suggesting that this size is a lower magnitude limit for producing permanent effects in the caves deposits. The speleoseismites we studied collected must have been generated by larger magnitude events, and/or with different epicenter locations. This study adds medium or large earthquake events, previously lacking, to the historic and instrumental record. This may contribute to reduction of gaps in the earthquake record and consequently a more reliable recurrence interval estimate for damaging earthquakes in the region.

High-resolution aeromagnetic survey of Calabria (Southern Italy)

ABSTRACTWe present a 1:350,000 high-resolution magnetic anomaly map of Calabria (Southern Italy), obtained by merging the results from two low-altitude aeromagnetic surveys performed in southern and northern Calabria. Magnetic anomalies of Calabria are of low intensity, and mostly range from 11 to –9 nT. Northern Calabria is characterized by positive anomalies in the Tyrrhenian margin (Coastal Chain) that turn into negative values moving eastward in the Sila Massif. Southern Calabria is characterized by slightly positive anomaly values, interrupted by a null magnetic anomaly corridor roughly corresponding to the eastern margin of the Gioia Tauro basin. Finally, anomaly values turn systematically negative in the Messina Straits. Due to the unprecedented resolution (low flying height, spatial sampling along the flight line of ∼5 m and 1–2 km flight line spacing), the new map highlights, in detail, the geometry and setting of the upper crustal features. As Calabria is one of the most seismically active regions in Italy, hit by several high-magnitude earthquakes in recent centuries, the interpretation of this new map will hopefully contribute to new insights into the crustal geological setting, location and dimension of the main seismogenic sources.

Grooved stone tools from Calabria region (Italy): Archaeological evidence and research perspectives

Since the end of the 19th century the Calabria region in southern Italy has been known for an abundance of grooved stone axes and hammers used during late prehistory. These artefacts are characterized by a wide and often pronounced groove in the middle of the implement, thought to have aided securing the head to a wooden haft. Their widespread presence is known both in prehistoric archaeological literature and in the archaeological collections of various regional and extra-regional museums. At first, scholars did not relate these tools to the rich Calabrian ore deposits and to possible ancient mining activities; they were regarded simply as a variant of ground lithic industry of Neolithic tradition. However, between 1997 and 2012, about 50 tools were discovered in the prehistoric mine of Grotta della Monaca in northern Calabria where there are outcrops of copper and iron ore. This allowed us to recognize their specific mining value and to consider them as a sort of “guide fossil” for the identification of ancient mining districts. This paper presents the results of a study involving over 150 tools from the entire region, effectively demonstrating an almost perfect co-occurrence of grooved axes and hammers with areas rich in mineral resources, especially metalliferous ores.

Use of mean residence time of water, flowrate, and equilibrium temperature indicated by water geothermometers to rank geothermal resources. Application to the thermal water circuits of Northern Calabria

A new hydro-geochemical survey was carried out on the thermal sites of Northern Calabria. By use of new and historical data, it was possible to improve the knowledge on the deep systems of interest. First, thermal waters were characterized by means of a classical approach, including water classifications, use of the triangular diagram of Cl-Li-B, and geothermometry through suitably selected functions. Then, the tritium-based mean residence time and flowrate of the thermal waters of Northern Calabria were used to evaluate the volume of the geothermal reservoir and its component terms. Based on these results, the heat stored in the geothermal reservoir was computed by means of the volume method. Their natural heat discharge was also calculated. These parameters as well as the reservoir temperature indicated by water geothermometers were used to rank the geothermal resources of Northern Calabria. Sambiase resulted to be the thermal circuit of highest geothermal potential.

Nothocasis rosariae sp. n., a new sylvicolous, montane species from southern Europe (Lepidoptera: Geometridae, Larentiinae).

In this paper, we describe Nothocasis rosariae sp. n. as the second European species belonging to the genus Nothocasis Prout, 1937. Differential features from its allopatric sibling species N. sertata (Hübner, 1817) are presented basing on wing pattern, morphology of male and female genitalia, and molecular data (COI barcode region). The type series is designated from southern Italy, but one examined specimen was collected in Epirus, Greece. The largest phenotypic and genetic variation was observed in the Pollino Massif, northern Calabria, whilst the population of the locus typicus in the Sila Massif, central Calabria, appears to be more homogeneous. 128 individuals were collected in mountainous beech forests from late August to mid-November. We hypothesize that larvae of N. rosariae sp. n. feed on Fagus sylvatica whilst those of its sibling species, N. sertata, feed on Acer.

Naturally occurring asbestos (NOA) in rock and soil and relation with human activities: the monitoring example of selected sites in Calabria (southern Italy)

The major aim of our research is to assess the occurrence, within the serpentinites and serpentinite-derived soils located in the area of Sila Piccola (northern Calabria), of asbestiform minerals that could be potentially harmful for human health. At this purpose, nine serpentinite rock samples and three agricultural soils have been collected nearby two inhabited centres (Gimigliano and Conflenti towns) and characterized in detail by means of Polarized Light Microscopy (PLM), X-Ray Powder Diffractometry (XRPD), Scanning Electron Microscopy combined with Energy-Dispersive Spectrometry (SEM/EDS). Further characterization by Differential Scanning Calorimetry (DSC), Thermogravimetric (TG) and by μ-Raman spectroscopy (μ-R) have allowed the discrimination among the three serpentine polytypes. Serpentinites from Gimigliano mainly consist of lizardite, antigorite while chrysotile is the dominant asbestos phase in the samples from Conflenti. Moreover in both investigated sample groups asbestos tremolite- actinolite was also detected. Furthermore, high amounts of chrysotile and asbestos tremolite-actinolite were found in agricultural soils, suggesting that human activities can disturb and provoke the release of inhalable asbestos in the atmosphere, triggering thus mechanisms of hazardous exposition for population.

GIS-based statistical analysis for assessing shallow-landslide susceptibility along the highway in Calabria (southern Italy)

In this work a GIS-based statistical analysis was used to evaluate shallow-landslide susceptibility along a section of highway A3, Salerno-Reggio Calabria, between Cosenza Sud and Altilia (northern Calabria, Italy). The study applies the weight of evidence (WofE) method, which is useful in determining landslide susceptibility in large areas with complex geological and geomorphological settings. The statistical analysis is based on past shallow-landslides, geological, pedological and topographic factors, which represent the most relevant landslide predisposing factors. The quality of the proposed model, particularly the fitting performance, was assessed; the landslide database was divided into a training set to obtain the model and a testing set to estimate the model quality. The susceptibility map was classified into five susceptibility classes: very low, low, moderate, high, and very high. About 34% of the study area falls in high to very high susceptible classes and most of the landslides mapped (86%) occur in the same classes. The validation results showed satisfactory agreement between the susceptibility map and the landslides locations; over 83% of the landslides of the testing set are correctly classified falling in high and very high susceptibility areas. Also, the prediction rate curve had shown an area under curve (AUC) value of 80.2% which demonstrates the robustness and good reliability of the landslide susceptibility model. According to these results, we conclude that the map produced by the WofE model is reliable and the methodology applied in the study produced high performance, and satisfactory results, which may be useful for land planning policy.

Interplay between land use changes and soil erosion in a small mountainous catchment in southern Italy

Land use is one of the most important factors controlling soil erosion. Moreover, erosion rates may vary through time as a response to land use changes. The aim of this work was to analyze the main land use changes in the last 60 years and to assess the relationships between them and spatial and temporal distribution of soil loss at catchment scale.The study was carried out in the Torano catchment (northern Calabria), which is representative of wide sectors of Calabria Region, where the overall soil erosion susceptibility is high. Aerial photos interpretation of different years (1954 and 2012), and field survey were used to assess and map types and variations of land use in the study area. The mean annual rate of soil erosion and the effects of land use changes on soil erosion since 1954 to 2014 were analyzed by using the revised universal soil loss equation (RUSLE) in a GIS environment.Results showed that the total soil loss estimated in the Torano catchment was 2216.76 t yr-1 in 1954, 3242.22 t yr-1 in 2014. Furthermore, the rate of mean annual soil loss increased from 4.30 t ha-1 yr-1 in 1954 to 6.29 t ha-1 yr-1 in 2014. Increasing erosion rates was mainly caused by the transformation of natural forest, scrub and pasture areas into crop fields. In addition, from 1954 to 2014 the barren land progressively increased from 0.2% to more than 2 %; in these areas and the highest soil loss values were observed. The increase of cultivated and barren lands, from 1954 to 2014, caused a 46.3 % increase soil loss. Therefore, the spatio-temporal changes of land use in the Torano catchment had an important role on soil erosion control.

Water-rock interaction in the ophiolitic aquifers of Northern Calabria

In this study, data acquired on local rocks, minerals, and shallow groundwaters were used to reconstruct the irreversible rock-to-water mass exchanges occurring during weathering of metabasalts and serpentinites of Northern Calabria, by means of reaction path modeling and taking into account the dissolution kinetics of relevant mineral phases. Groundwater analyses were performed on 69 spring waters and showed a prevalence of Ca–HCO3 over Mg–HCO3 compositions suggesting that groundwaters interact chiefly with metabasalts and secondarily with serpentinites.

A Neogene-Quaternary Geotraverse within the northern Calabrian Arc from the foreland peri-Ionian margin to the backarc Tyrrhenian margin

A Neogene-Quaternary Geotraverse within the northern Calabrian Arc from the foreland peri-Ionian margin to the backarc Tyrrhenian margin

The Calabria-Peloritani Orogen, a composite terrane in Central Mediterranean; its overall architecture and geodynamic significance for a pre-Alpine scenario around the Tethyan basin

The Calabria-Peloritani Orogen is an arcuate segment of the peri-Mediterranean orogenic Alpine nappe system that comprises the whole Calabria and the north-eastern sector of Sicily. It comprises the Sila and Catena Costiera Massifs in northern Calabria, the Serre and Aspromonte Massifs in central and southern Calabria, and the Peloritani Mountains in Sicily. In Sila and Catena Costiera Massifs, three tectonic complexes are recognisable: a) the basal Apennine Complex, which consists of carbonate platform sequences of passive continental margin; b) the intermediate Liguride Complex, made of oceanic-derived units, affected by HP/LT metamorphism; and c) the upper Calabride Complex, which represents a nearly entire section of continental crust. The Catanzaro Line separates the northern sector from the Serre Massif that also represents a nearly entire segment of Variscan continental crust unaffected by Alpine metamorphism. Further to the south, the Palmi Line separates the Serre from the Aspromonte Massif and the Peloritani Mountains. These two latter nappe edifices consist of either Variscan metamorphic units, Variscan units with Alpine overprint and units of continental derivation that are exclusively affected by Alpine metamorphism. The comparison between the geological evolutions of the various chain sectors, as well as their structural setting and their direction of tectonic transport, indicates that the Calabria-Peloritani Orogen is a composite terrane derived from the amalgamation of crustal blocks of different continental provenance. Northern Calabria represents a fragment of the Adria palaeomargin, whereas southern Calabria and northeastern Sicily are relics of an accretionary wedge resulting from the deformation of the European continental margin. As a consequence, nowadays a segment of the Europe-Adria collisional suture crops out in central Calabria.

Integrating multidisciplinary, multiscale geological and geophysical data to image the Castrovillari fault (Northern Calabria, Italy)

Integrating multidisciplinary, multiscale geological and geophysical data to image the Castrovillari fault (Northern Calabria, Italy)

The Small Spring Method (SSM) for the definition of stable isotope–elevation relationships in Northern Calabria (Southern Italy)

A total of 141 samples mostly located in the Coastal Chain and the Sila Massif of Northern Calabria have been collected from 125 different springs and analyzed chemically and for the isotopic ratios 2H/1H and 18O/16O of water, with the ultimate aim to investigate isotope–elevation relationships for local meteoric waters. The Small Springs Method (SSM) has been adopted for this purpose. The hydrogeological characteristics of the watersheds of interest indicate that the sampled springs are discharged from water circuits hosted in alluvial and colluvial deposits rather than in the underlying rock substrata. The chemical characteristics of the sampled waters suggest that they are immature and related to shallow and short water circuits, in spite of the variable degree of chemical evolution. The spring waters of relatively high Total Ionic Salinity (TIS >12.5 meq/L) and those from watersheds of comparatively large elevation range (>650 m) and relatively large areas (>17 km2) have been excluded from the analysis of elevation–isotope relationships. An oxygen isotope lapse rate of −0.194 ‰/100 m has been found for the spring water samples of Northern Calabria as a whole, whereas the obtained hydrogen isotope lapse rates are −1.23 ‰/100 m for the Coastal Chain and −1.45 ‰/100 m for the Sila Massif based on measured isotope values and optimized elevation. The following O-isotopes equation is recommended to estimate the average elevation (Hi in m) of the recharge areas of Northern Calabria aquifer systems:δO18=−0.00194·Hi−5.91 (1)The maximum estimated uncertainty due to variations in the δ18O value over time is 202 m. Use of H isotopes is not recommended for constraining average recharge elevations due to important local variations, reflecting in different relations for the Coastal Chain and the Sila Massif. Assuming that Equation (1) holds true throughout Northern Calabria, an iso-distribution map of the δ18O value in rainfall has been drawn for this area.

Eighteen years of GPS surveys in the Aeolian Islands (southern Italy): open data archive and velocity field

<p>Since the early 1970s, geodetic networks became a most important tool to monitor the present day deformations of the volcanic arc of the Aeolian Islands. The first benchmarks were installed in this region at Lipari and Vulcano Islands and the number of GPS benchmarks increased in time since the early ’90s. These networks were periodically surveyed in the frame of national and international geodynamic projects and for Civil Protection programs devoted to the mitigation of the volcanic hazard. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) played a fundamental role in the realization and periodical reoccupation of these networks, with the goal to investigate the tectonic and volcanic processes, still active in this crucial area of the central Mediterranean. An updated GPS velocity map for this region, both for the horizontal and vertical component of land motion, with details for Lipari, Vulcano and Panarea Islands, is provided in this paper. The presented GPS velocity field also includes a set of additional discrete stations located in northern Sicily and Calabria together with data from the available CGPS networks active in southern Italy. Here we show the results from eighteen years of repeated GPS surveys performed in this region in the time span 1995-2013 and the open access AINET-GPS data archive, now freely available for the scientific community. Data will support scientific research and hopefully improve the assessment of volcanic and seismic hazard in this region.</p>

Imaging of an active fault: Comparison between 3D GPR data and outcrops at the Castrovillari fault, Calabria, Italy

We have integrated and analyzed a 3D ground-penetrating radar (GPR) volume with a trenching exposure data set to evaluate the potential of these methods individually and combined for study of a fault zone. We chose a test site across a branch of the active Castrovillari fault in the Northern Calabria (Southern Italy). This tectonic structure is one of the most active in the area, and it has generated strong earthquakes in the past. Based on analysis of previously collected data, a 3D GPR survey was carried out 1.2 m from a fault outcrop. The goal was to use the GPR volume to guide and optimize the excavation of a trench and then to use the trenching data to validate the GPR volume interpretation. We used seismic interpretation software to display vertical and horizontal sections and for horizon tracking and attribute analyses. We obtained quantitative information on the geometry of structural and geologic features, such as fault strike and dip angle, defining the boundaries of different stratigraphic units. We validated our GPR data interpretation with the outcrop section and trench wall demonstrating the benefits of GPR in extensional tectonics environments and the great potential of the combined geologic and geophysical approach.

From west to west: Determining production regions of Mycenaean pottery of Punta di Zambrone (Calabria, Italy)

The article reports on the results of provenance analyses by NAA on pottery of Aegean type found at the settlement of Punta di Zambrone in southern Calabria (Italy). The analyzed pottery predominantly consists of Mycenaean-type vessels and to a lesser degree of Minoan-type vessels and was excavated in strata dating to the Italian Recent Bronze Age. The majority belongs to the phase LH IIIC Early while a few pieces are of older date (LH IIIB). The NAA results assign the largest part of the 44 analyzed vessels to production regions in western Greece and mainly to the northwestern Peloponnese. Other Aegean regions represented among the sample include Laconia, Boeotia and western Crete. No local products of the region of Punta di Zambrone could be identified but some pots stem from workshops in northern Calabria. These results considerably change the picture of Mycenaean pottery use in southern Italy from the 13th to early 12th centuries BCE.