Ophiolitic sequences from the central sector of the Catena Costiera (Calabria): stratigraphy, petrology and structural analyses

Mesozoic ophiolites crop out in the Catena Costiera (Northern Calabrian Arc). The Northern Calabrian Arc is characterized by the superposition of three structural elements (OGNIBEN, 1973): the uppermost Hercynian continental section intruded by late- Variscan granitoids (Calabrian Nappe), the intermediate ophiolitic Nappe and the lowermost Mesozoic passive margin carbonate sequences (Apenninic Units). The studied area is located in the central Catena Costiera (fig. 1) where the ophiolitic sequences are characterized by both aphyric and porphyritic metabasalts with a T-MORB affinity (LIBERI et alii, 2006). They represent the basement of a peliticarenaceous metasedimentary sequence, previously interpreted as a pre-Mesozoic continental basement (Bagni Unit of AMODIO MORELLI et alii, 1976). In the metasedimentary cover, a remarkable increase in the carbonatic supply is noticed moving from south to north of the study area. According to this evidence two stratigraphic sequences have been defined for the southernmost Cozzo Cervello area and the northernmost San Martino di Finita area. The Cozzo Cervello area ophiolitic sequence is characterized by: metabasites, thin levels of volcanoclastic metasediments, rare metacarbonates, metapelites and metarenites. The San Martino di Finita area ophiolitic sequence is instead characterized by: metabasites, volcanoclastic metasediments and calcschists. The studied rocks underwent a polyphase deformation history and the meso- and microstructural analyses allowed distinguishing three main (D1-D3) deformation phases: – D1, this phase is characterized by a S1 foliation locally developed and preserved as microlithons inside the S2 main foliation; – D2, a N-S trending isoclinal folding event (F2; fig. 2 a,b) is responsible for the formation of the S2 foliation (fig. 2 d), that represent the main surface recognizable in the field; – D3, this phase is characterized by asymmetric folds (F3) developed at different scales and showing a WNW-ESE trending axes. An incipient foliation (S3) is locally developed in the phyllosilicate-rich levels (fig. 2 c,d). *Dipartimento di Scienze della Terra, Università della Calabria. ([email protected]) **Dipartimento di Scienze della Terra, Università di Pisa The petrographic analysis allows to define the mineralogical assemblage of the different lithotypes and to determine the relationships between deformation and blastesis. The metabasites are characterized by the mineralogical assemblage: Epidote + Na-amphibole + Lawsonite + Phengite + Chlorite + Albite Calcite Quartz + Magnetite. Metapelites and metarenites are characterized by: Epidote + Phengite + Stilpnomelane + Na-Amphibole + Pumpellyite + Chlorite + Albite + Quartz + Magnetite. The calcschist are constituted by: Calcite + Phengite + Chlorite + Albite + Quartz + Magnetite. The described mineralogical assemblages suggest that the studied rocks underwent P-T conditions typical of the blueschist facies as suggested by the blastesis of Na-amphiboles, lawsonite, stilpnomelane and phengite along the S2 foliation. The blastesis of white mica can be observed along the S3 foliation also. The following metamorphic retrogression developed within the prehnitepumpellyite facies and is characterized by a static recrystalization. Fig. 1 – Tectonic sketch map of central sector of the Catena Costiera, after LIBERI et alii (2006). 64 OPHIOLITIC SEQUENCES FROM THE CATENA COSTIERA 65 Fig. 2 – a) isoclinal folds (F2) in the metapelites of Cozzo Cervello area; b) isoclinal folds (F2) in the calcschists of San Martino di Finita area; c) crenulation F3 in the metabasites; d) microscopic view of the main foliation S2 deformed by the later D3 phase in the metapelites. The white line indicates white mica flakes along S3. The field study and the tectonometamorphic evolution reconstructed for the ophiolitic sequences cropping out in the central sector of the Catena Costiera of Calabria show that a subduction and exhumation history inside an accretionary wedge can be proposed. In particular, the characterization and the definition of the complex relationships existing within the ophiolitic metasedimentary cover allow us to propose: 1. the source area was composite, with both carbonatic and siliciclastic contributions; 2. the presence of terrigenous deposit, even in the lowermost part of the sedimentary sequence, seem to indicate that this part of oceanic crust was located close to the continental margin; 3. the San Martino di Finita type sedimentary cover can be correlated with that of the Malvito ophiolitic unit (sensu AMODIO MORELLI et alii, 1976), cropping out in the northernmost sector of the Catena Costiera; 4. the subdivision between the Bagni and Gimigliano-Monte Reventino Units, as proposed by DIETRICH & SCANDONE (1972) and AMODIO MORELLI et alii (1976) for the study area, is not supported by the data collected in this work. REFERENCES AMODIO MORELLI L., BONARDI G., COLONNA V., DIETRICH D., GIUNTA G., IPPOLITO F., LIGUORI V., LORENZONI S., PAGLIONICO A., PERRONE V., PICCARRETA G., RUSSO M., SCANDONE P., ZANETTIN-LORENZONI E. & ZUPPETTA A. (1976) - L’arco Calabro-peloritano nell’orogene appenninicomagrebide. Mem. Soc. Geol. It, 17, 1–60. DIETRICH D. & SCANDONE P. (1972) - The position of the basic and ultrabasic rocks in the tectonic units of the southern Apennines. Atti Acc. Pont., 21, 61–75. LIBERI F., MORTEN L. & PILUSO E. (2006) - Geodynamic significance of the ophiolites within the Calabrian Arc. Island Arc, 15, 26–43. OGNIBEN L. (1973) - Schema geologico della Calabria in base ai dati odierni. Geologia Romana, 12, 243

Evoluzione tettonometamorfica dell'unita' di polla-copanello nel settore settentrionale della catena costiera tirrenica calabrese

Dottorato di ricerca in tettonica e geologia strutturale. 9. ciclo. Relatore L. MortenConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Il cuneo di accrezione alpino nel settore centrale della catena costiera (Calabria Settentrionale): vincoli geologico-strutturale e petrologici

Scuola di Dottorato “Archimede” in Scienze, Comunicazione e Tecnologie, Dottorato di Ricerca in Scienze della Terra, XXV Ciclo, a.a. 2010-2012Università della Calabri

Natura ed evoluzione delle rocce ultramefiche in Calabria settentrionale

Dottorato di Ricerca in Scienze e Ingegneria dell'Ambiente, delle Costruzioni e dell'Energia. Ciclo XXIXContinental Sila and oceanic Gimigliano-Monte Reventino tectonometamorphic Units that outcrop in northern Calabria contain small ultramafic rocks bodies. The ultramafic rocks of the Sila Unit are embedded within the northern Calabria alpine chain and preserve evidence of the pre-alpine extensional tectonics related to lithospheric thinning in Permo-Triassic time. The Sila Unit consist of a continuous continental lithospheric section in which the ultramafic rocks represent the subcontinental upper mantle components. The ultramafic rocks of the Gimigliano-Monte Reventino Unit represent the suboceanic upper mantle and was interpreted as remnants of the Jurassic Alpine Tethys ocean realms subsequently involved in the Alpine accretionary wedge. The mantle rocks of the Sila Unit are made of layered alternations of serpentinized peridotities and concordant pyroxenites. The serpentinites are after Spl-harzburgites-dunites. The concordant pyroxenites range from olivine-bearing orthopyroxenite to orthopyroxenite in composition. The olivine-bearing orthopyroxenites and the orthopyroxenites have been produced by melt-rocks interaction processes under Spl-lherzolitic facies conditions. Locally the concordant pyroxenites shows extensional tectonic effects whit formation of drawn boudins. The subsolidus evolution of the Sila Unit upper mantle rocks can be described by four main stages from Spl-lherzolite facies to Chl-lherzolite facies followed by a severe serpentinization. Moreover, evidence of metasomatism produced by melt-rock interaction has been observed at meso- and microscale. On the base of field work and microstructural evidence two main metasomatizing agents have been observed: (i) discordant dykes orthopyroxenitic in composition; (ii) concordant orneblendites with tholeitic affinity. Melt-rock interaction processes was responsible for the local transformation of: (i) Spl-peridotites into hercynitic spinel-bearing peridotites and (ii) concordant pyroxenites into websterites. Gabbroic magmatism occurred at P ≈ 0.55 GPa (Liberi et al., 2011). Thermobarometric estimates based on Opx-Cpx pairs from olivine-bearing othopyoxenites and websterites given values of 808-855°C and 0,7 GPa respectively for T and P. These physical conditions are consistent with the transition from Spl- to Amph-lherzolite facies. Finally, greenschist facies retrogression is documented by static serpentinization and by the development of late vein systems filled by serpentine mineral groups. At this stage chrysotile and lizardite crystallize. This fact suggests equilibrium at T<300°C. The serpentinites and ophicarbonates occur in the Gimigliano-Monte Reventino Unit at the core of the antiform structures. The serpentinites are after depleted lherzolites and in some preserve the protogranular textures. The ophicarbonate shows typical brecciated textures given by clasts of peridotites severely serpentinized surrounded by a matrix made of carbonates and serpentine minerals. The ultramafic rocks are in tectonic contact with the metabasites along a narrow cataclastic-mylonitic shear zone where can be observed a grain size reduction of serpentinite clasts in a matrix made of calcite and tremolite. Therefore, the petrogenetic evolution of the northern Calabria ultramafic rocks document a Ocean Continent Transition (OCT) which was part of the Tethyan hyperextended margin. Again, northern Calabrian ultramafics preserve the signals of the transition from late-hercinian orogenic extention to Tethyan rift, followed by the Alpine and subsequent compression stages in the Apennine tectonic phases.Università della Calabri

Genesi ed evoluzione del magmatismo basico nelle successioni carbonatiche triassiche nel Complesso Alpujárride (Cordigliera Betica) e nelle Unità Appenniniche della Calabria settentrionale

Scuola di Dottorato “Archimede” in Scienze, Comunicazione e Tecnologie, Dottorato di Ricerca in Scienze della Terra, XXV Ciclo, a.a. 2012Permo-Mesozoic extension represents one of the most noticeable geological processes in the western Mediterranean. Triassic sedimentary sequences observed along the Dinaride-Hellenide orogenic belts and in Betic Cordillera are locally related with a basic magmatism in an extensional tectonic setting. Carbonates sequences which include basic rocks can be observed in the Alpujarride Complex (central-eastern Betic Cordillera, Spain) and in the Lungro-Verbicaro Unit (northern Calabria). Betic Cordillera represents an important orogenic belt sited in the southern and southeastern side of the Iberian Peninsula and it is commonly divided into three main geological units: the Betic External Zone, Campo de Gibraltar Complex and the Betic Internal Zone, which include various tectonostratigraphic units arising from previous paleogeographical domains developed during the Mesozoic, as a consequence of the break-up of the Pangaea supercontinent. According to Iannace et al. (2007), the Meso-Cenozoic carbonates sequences outcropping in northern Calabria can be grouped into three tectonic units: the Lungro-Verbicaro Unit, the Cetraro Unit and the Pollino-Ciagola Unit. The Lungro-Verbicaro Unit is represented by a thick sedimentary succession affected by HP-LT metamorphism and consisting of phyllites and metarenites with carbonate intercalations in its lowermost part of Middle Triassic. Basic rocks can be found as a small intrusive complex within the Anisian phyllites and the Ladinian-Carnian carbonates of the Lungro-Verbicaro Unit. As Mesozoic geodynamic processes, since the opening of the Tethys, are recorded in the above rocks, the attention was focused on these two areas. The aim of this research was to study these basic magmatic rocks in order to obtain a better interpretation of the extensional tectonic process and to recognize a possible hydrothermal metamorphic overprint. In fact, the latter process is suggested by significant mineralizations observed in the outcrops of the Alpujarride Complex, due to the activity of a hydrothermal metamorphism in the Betic area. Basic rocks were characterized from a petrological and geochemical standpoint with the purpose of determining the characteristics of their source. A multidisciplinary approach was followed in both areas. Firstly, a field geology work (with the addition of photo-geological analyses for the Betic area) was performed to constrain relationships between basic rocks and wall rocks. Secondly, laboratory analyses were carried out in order to determine petrographic, petrological and geochemical characteristics of study samples. Petrographic analyses were performed using both the optical and scanning electron microscopy techniques, whereas petrological data were obtained by the electron microprobe. Lastly, geochemical composition of study rocks was characterized by X-ray fluorescence spectroscopy (XRF), and the obtained data were processed using suitable diagrams.Università della Calabri

Volcanic Holocrystalline Bedrock and Hydrothermal Alteration: A Terrestrial Analogue for Mars

Clay minerals have been detected on Mars to outcrop mainly as alteration of ancient bedrock, and secondarily, as deposition from aqueous environments or interlayered with evaporitic deposits on Mars. In order to better constrain the alteration environments, we focused on the process to form clays from volcanic rocks and experimentally reproduced it at different temperature and pH. A fresh, holocrystalline alkali-basalt sample collected in the Mount Etna volcanic sequence has been used as analogue of the Martian unaltered bedrock. Previous works considered only volcanic glass or single mineral, but this may not reflect the full environmental conditions. Instead, we altered the bulk rock and analyzed the changes of primary minerals to constrain the minimum environmental parameters to form clays. We observed that under acidic aqueous solution (pH ~ 3.5&ndash;5.0) and moderate temperature (~150&ndash;175 &deg;C), clinopyroxene and plagioclase are altered in smectite in just a few days, while higher temperature appear to favor oxides formation regardless of pH. Plagioclases can also be transformed in zeolite, commonly found in association with clays on Mars. This transformation may occur even at very shallow depth if a magmatic source is close or hydrothermalism is triggered by meteoritic impact

Geological map of the central area of Catena Costiera, Northern Calabria

The 1:25.000 scale geological map of the central area of Catena Costiera aims to provide a picture of the tectonic setting of the metamorphic units belonging to the Alpine collisional belt of Northern Calabria, Italy. The exposed successions of the study area have been investigated by structural analyses, petrographic, petrological and geochemical studies whose results are summarised in the geological map. In this area, two HP-LT metamorphic, oceanic-derived units, referred as the Mongrassano and Cozzo Cervello units, have been distinguished on the base of their stratigraphic and tectono-metamorphic evolution. Both the oceanic-derived units show a polyphase deformation history developed under retrograde metamorphism in a subduction zone by underplating and exhumation into an accretionary wedge. These units are overthrust by continental-derived units, referred as the Sila and Castagna units, consisting of medium and high-grade metamorphic rocks. While the Castagna unit displays an Alpine HP/LT metamorphic overprint, the Sila unit escaped any subduction-related metamorphism

Copy Number Variants Account for a Tiny Fraction of Undiagnosed Myopathic Patients

Next-generation sequencing (NGS) technologies have led to an increase in the diagnosis of heterogeneous genetic conditions. However, over 50% of patients with a genetically inherited disease are still without a diagnosis. In these cases, different hypotheses are usually postulated, including variants in novel genes or elusive mutations. Although the impact of copy number variants (CNVs) in neuromuscular disorders has been largely ignored to date, missed CNVs are predicted to have a major role in disease causation as some very large genes, such as the dystrophin gene, have prone-to-deletion regions. Since muscle tissues express several large disease genes, the presence of elusive CNVs needs to be comprehensively assessed following an accurate and systematic approach. In this multicenter cohort study, we analyzed 234 undiagnosed myopathy patients using a custom array comparative genomic hybridization (CGH) that covers all muscle disease genes at high resolution. Twenty-two patients (9.4%) showed non-polymorphic CNVs. In 12 patients (5.1%), the identified CNVs were considered responsible for the observed phenotype. An additional ten patients (4.3%) presented candidate CNVs not yet proven to be causative. Our study indicates that deletions and duplications may account for 5–9% of genetically unsolved patients. This strongly suggests that other mechanisms of disease are yet to be discovered.Next-generation sequencing (NGS) technologies have led to an increase in the diagnosis of heterogeneous genetic conditions. However, over 50% of patients with a genetically inherited disease are still without a diagnosis. In these cases, different hypotheses are usually postulated, including variants in novel genes or elusive mutations. Although the impact of copy number variants (CNVs) in neuromuscular disorders has been largely ignored to date, missed CNVs are predicted to have a major role in disease causation as some very large genes, such as the dystrophin gene, have prone-to-deletion regions. Since muscle tissues express several large disease genes, the presence of elusive CNVs needs to be comprehensively assessed following an accurate and systematic approach. In this multicenter cohort study, we analyzed 234 undiagnosed myopathy patients using a custom array comparative genomic hybridization (CGH) that covers all muscle disease genes at high resolution. Twenty-two patients (9.4%) showed non-polymorphic CNVs. In 12 patients (5.1%), the identified CNVs were considered responsible for the observed phenotype. An additional ten patients (4.3%) presented candidate CNVs not yet proven to be causative. Our study indicates that deletions and duplications may account for 5–9% of genetically unsolved patients. This strongly suggests that other mechanisms of disease are yet to be discovered.Peer reviewe