Dipartimento di Biologia, Ecologia e Scienze della Terra - Tesi di dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento Dipartimento di Biologia, Ecologia e Scienze della Terra dell'Università della Calabria.

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Author: search.filters.author.Critelli, Salvatore

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    Facies analysis and fluid inclusion studies of the Messinian evaporites, Calabria, Southern Italy
    (Università della Calabria, 2020-03-26) Cipriani, Mara; Critelli, Salvatore; Costanzo, Alessandra; Dominici, Rocco
    Messinian salinity crisis (MSC) is, from about 30 years, one of the most important and debated topic in the scientific community, both in environment and economic field. In this context, Calabrian evaporite deposits, poorly investigated in the past, offer an interesting opportunity to expand the knowledge because they confirm and increase the models created for other Mediterranean basins, and add important information on the main halite and gypsum facies. In this regard, saline evaporitic facies outcropping in the Crotone, Catanzaro and Ionic Basins were investigated using a multidisciplinary approach from classical petrography, to the study of fluid inclusions (FIs) to isotopic geochemistry. (A) The halite samples from the Crotone Basin have highlighted three primary facies; two known in the literature as banded and white while the third, never observed before, called in this work transparent. The transparent facies seems recrystallized but the analyses conducted show instead a primary origin. The three facies form in different environment and with a dissimilar deposition rate (fast or slow) due to pycnocline oscillation (daily or seasonal). Pycnocline oscillations can explain the different temperature of homogenization found within the FIs (from +20° to +33°C). The facies form in a hybrid brine (salinity av. ̴ 26.2 eq. wt% NaCl) enriched in Ca-Mg-Na-K-Cl elements, regardless of their deposition rates. During their fluid inclusions testifying plastic and ductile deformations that don’t remove primary features, demonstrating low recrystallization during burial process. Moreover, isotopic data attribute these facies at the second step of the MSC (5.6-5.5 Ma) during Halite deposition stage in the Mediterranean Basin. (B) The selenite samples from the Catanzaro Trough belong to banded and giant facies. The crystals record middle-frequency climatic oscillation between the depositional cycles and high-frequency climatic oscillation (seasonal) between cloudy and clear microfacies observed within the crystals. These microfacies testify a different brine condition associated with seasonal variation: cloudy intervals form during continental water inflow in the humid phase (Mg and Ca as dominant elements and low salinity values - av. ̴ 3 eq. wt% NaCl), while, clear intervals form in marine water during the arid phase (Na, K and Cl as dominant elements and high salinity values - av. ̴ 21.5 eq. wt% NaCl). Isotopic data attribute these facies at the third step of the MSC (5.5-5.3 Ma) placing, for the first time, the formation of the giant facies at the Upper Gypsum stage in the Mediterranean Basin. (C) The analyses conducted on the gypsum deposit from the Ionian Basin have shown that these crystals do not display primary features. This deposit is an olistostrome. The isotopic data confirm secondary origin attributing these facies at the second step of the MSC (5.5-5.3 Ma) during the Resedimented Lower Gypsum deposition stage in the Mediterranean Basin. The data obtained from the study of the Calabrian Messinian deposits indicate a surprising variety and diversity of evaporitic facies. In this work, it emerges that the formation of, crystals trap primary FIs and microalgae (blue, green and yellow). Primary FIs and organic matters, associated with secondary the different facies is strongly conditioned by climate (wet/arid) and intrinsic characteristics of the basin (depth, arrival of continental water flows etc.) which promote the development of one facies rather than of another.
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    Geochemical modelling of natural contaminants in groundwaters and their removal by membrane processes
    (Università della Calabria, 2021-10-25) Fuoco, Ilaria; Critelli, Salvatore; Apollaro, Carmine; Marini, Luigi; Bartolo, Gabriele; Figoli, Alberto; De Rosa, Rosanna
    The presence of harmful elements dissolved in groundwaters represents one of the main environmental issues of present times. The aim of my PhD Thesis was to study the rock-to-water release and the fate of some inorganic pollutants dissolved in the groundwaters of the Calabria Region, and sometimes in other Italian areas, as well as to select suitable membrane technologies for their removal based on the acquired geochemical knowledge. Taking into account the peculiar characteristics of the groundwaters of the Calabria Region, three elements were considered: arsenic (As), fluorine (F) and chromium (Cr). The salient results of my PhD studies are presented in this Thesis, which is organized in four self-consistent Chapters structured as follows. Chapter 1. Geochemical modelling of As and F release into the crystalline aquifers of the Calabria Region. This section has been devoted to understanding the water-rock interaction processes occurring in the crystalline aquifers of the Calabria Region. Three different reaction path modeling exercises of granite dissolution were performed, reconstructing the water-rock interaction processes which occur: (i) in shallow and relatively shallow crystalline aquifers in which no As and F anomalies were observed; (ii) in As-rich areas, coupling the reaction path modeling of granite dissolution with the simulation of the adsorption of dissolved As onto precipitating crystalline and amorphous hydrous ferric oxide (HFO); (iii) in deep crystalline aquifers where high F concentrations were detected. A total of 160 water samples discharging from the crystalline aquifers of the Calabria region were used to fix the boundary conditions as well as to validate the outcomes of geochemical modeling. The results of the three geochemical modeling exercises of granite dissolution are in agreement with the analytical data and, therefore, it is reasonable to assume that they reproduce satisfactorily the water-rock interaction processes occurring during the travel of meteoric waters from shallow to deep crystalline aquifers, hosted both in granite rocks without mineralizations and in mineralized granites. Moreover, based on the results of the geochemical survey, some As- and F- rich groundwaters were selected and used as feeds for the treatment tests. Some relevant results have been already published by Fuoco et al. (2021a). Chapter 2. Geochemical modelling of Cr(VI) release into the ophiolite aquifers of Italy. This section has been focused on the water-rock interaction processes occurring in the main ophiolite aquifers of Italy. The obtained results were already published by Apollaro et al. (2019a). Reaction path modelling of serpentinite dissolution was performed varying the Fe2O3/(FeO +Fe2O3) weight ratio of serpentine and reproducing the analytical concentrations of relevant solutes, including Cr(VI), in the Mg-HCO3 groundwaters hosted in the ophiolite aquifers of Italy. The occurrence of geogenic Cr(VI) in these groundwaters appears to be potentially controlled by the oxidation of trivalent Cr to the hexavalent redox state, driven by the reduction of trivalent Fe to the divalent redox state. In fact, trivalent Fe is the only oxidant present in suitable amounts in serpentinite rocks, and even serpentine contains high contents of trivalent Fe as proven by recent studies. In contrast, the generally accepted hypothesis that geogenic Cr(VI) in waters interacting with serpentinites is driven by the 2 reduction of trivalent and tetravalent Mn is questionable. To validate the outcomes of the geochemical modeling of serpentinite dissolution and rock-to-water release of Cr(VI), the redox state of Fe in serpentine minerals of different Italian areas was measured (see next section). Moreover, the water sample characterized by the highest concentration of Cr(VI) was selected for the treatment tests. Chapter 3. Determination of the iron redox state in serpentine minerals by using TEMEELS analysis and its environmental implications. This section has been addressed to determine the Fe3+/FeT ratio of the serpentine minerals hosted in five serpentinite samples coming from the main ophiolite areas of Italy, in order to validate the results of the geochemical modeling of serpentinite dissolution and rock-to-water release of hexavalent chromium (see previous section). The electron energy-loss spectroscopy (EELS) combined with transmission electron microscopy (TEM) was selected as most suitable analytical technique because it provides the highest spatial and energy resolution allowing to obtain a good qualitative and quantitative information on iron redox speciation compared to other analytical techniques. Ten site-specific TEM foils were prepared and analyzed in the laboratories of the GFZ German Research Centre for Geosciences, in Potsdam. It has not been the simple application of a well-established analytical technique, but rather a challenging study, because it has been necessary to develop a new spectra processing method and prove its validity. The performed analyses provided in-depth knowledge on nanoscale structures of the studied samples and showed that Fe3+ represents from 75 to 85 % (median values) of total iron. The obtained results provide further support to the hypothesis concerning the oxidation Cr(III) to Cr(VI) driven by the concurrent reduction of Fe(III) to Fe(II), as suggested by geochemical modeling (see previous section). Chapter 4. Application of membrane processes to remove As, F and Cr(VI) from contaminated groundwaters. This section has been devoted to the removal of As, F and Cr from polluted groundwaters by means of membrane processes. Relevant results have been already published by Figoli et al. (2020), Fuoco et al. (2020) and Fuoco et al. (2021b). The geochemical approach was used as strong-scientific tool for pre-selection of suitable remediation systems and the contaminated groundwaters were chosen from the previous data collections. Several type of commercial nanofiltration/reverse osmosis membranes, not already tested in the pertinent literature, were selected depending on the type of application. Their efficiency was evaluated in terms of arsenic, fluoride and chromium rejection, water production and feed composition. The other main ions that contribute to water chemistry were also taken into account to evaluate the possible intended use of the considered waters after the treatments. Satisfactory results were obtained for each specific case of contamination. Moreover, an innovative membrane with absorbent capacities against As(III) and As (V) species was developed and the preliminary results are quite promising. Summing up, the findings obtained in this work are useful for the understanding of the rock-to-water release of the chemical elements of interest and their fate in natural waters. Moreover, the treatment of natural As, F, and Cr-contaminated groundwaters improved the knowledge and the data availability for future scientific and application developments in similar geological settings worldwide.
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    Impianto Syndial-Eni di Cirò Marina (Kr): analisi geologica, ambientale e valutazione del livello del rischio (D.Lgs 81/2008)
    (2018-05-11) Spezzano, Luigi; Critelli, Salvatore; Barca, Donatella; Macario, Anastasia
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    Weathering ed esumazione di rocce plutoniche del massiccio della Sila durante il quaternario
    (2018-05-11) Coniglio, Sabrina; Critelli, Salvatore; Scarciglia, Fabio; Perri, Francesco
    I sedimenti sono il risultato dell’alterazione meccanica e biogeochimica delle rocce, dovuti agli stress tettonici e ai fenomeni di weathering in una determinata area sorgente (Hinderer, 2012). La natura e l’intensità del weathering dipendono principalmente da: fattori ambientali che controllano i processi alterativi; proprietà del materiale costituente la roccia-madre; caratteristiche dell’ammasso roccioso. Questi processi risultano particolarmente attivi nelle rocce ignee e metamorfiche, che, essendosi originate in condizioni di elevate temperatura e/o pressione, hanno la tendenza a sviluppare un profondo profilo di alterazione. La profondità dei profili di alterazione è molto variabile, in quanto risulta influenzata da una serie di fattori in cui il clima, il tempo, la tettonica ed il rilievo ne controllano l’età o determinano il ringiovanimento dei fronti stessi (Scarciglia, 2015). Stabilire l’origine e l’età del weathering in queste aree risulta, quindi, un problema di difficile soluzione, in quanto derivano dalla complessa interazione tra weathering e processi pedogenetici, dalla storia tettonica dell’area, dall’evoluzione geomorfologica del territorio e dai cambiamenti climatici avvenuti nel tempo. A questo, si aggiunge il fatto che nell’evoluzione del paesaggio i segni di tali processi sono spesso di difficile interpretazione, in quanto scarsamente preservati o addirittura totalmente cancellati dalla presenza di superfici di erosione, dal seppellimento sotto sedimenti più giovani o dalla sovraimposizione di processi di weathering più recenti (Scarciglia, 2015). La maggior parte dei massicci calabresi (la Sila, le Serre, l’Aspromonte) sono caratterizzati dalla presenza di litotipi plutonici e metamorfici che ne costituiscono l’ossatura (Messina et al., 1994;Messina et al., 2004; Caggianelli et al., 2000;Critelli et al., 2011, 2013; Van Dijk et al., 2000; Graessner et al. 2000; Liotta et al., 2008; Olivetti et al., 2012). La maggiore concentrazione di fenomeni d’instabilità si rileva proprio in corrispondenza di queste rocce cristalline alterate e caratterizzate da una sequenza di stadi a diverso grado di alterazione (Guzzetta, 1974; Ietto, 1975, Ietto & Ietto, 2004; Borrelli et al., 2015, 2016; Scarciglia et al., 2016). Tale circostanza è conseguenza di condizioni ambientali tali, da aver causato intensi processi di disgregazione e di degradazione indebolendo l’originaria struttura di queste rocce. Nell’analisi delle caratteristiche di decomposizione e degrado delle rocce cristalline calabresi, bisogna considerare che esse sono il risultato dell’insieme dei processi di weathering, che si sono susseguiti sin dalle prime fasi di sollevamento del Massiccio della Sila ad oggi. I terreni calabresi hanno subito numerose fasi tettoniche, a causa delle quali le rocce ignee e metamorfiche, si presentano intensamente fagliate e fratturate, il che ha favorito una profonda alterazione. Lo stato di weathering degli ammassi rocciosi calabresi, che presentano decine di metri di spessore di alterazione, è tipico di rocce cristalline in regioni caratterizzate da un rapido sollevamento. Gli studi, sicuramente numerosi, disponibili in tali aree solo da alcuni anni stanno trovando un più organico inquadramento generale. In Italia, già a partire dalla seconda metà degli anni settanta e con un consistente crescendo nell’ultimo decennio, si stanno sviluppando e consolidando studi e ricerche, anche a carattere interdisciplinare, relativamente a contesti dove sono ben evidenti gli effetti dell’alterazione sugli ammassi rocciosi cristallini (Borrelli et al., 2007, 2011, 2012, 2015; Cascini et al., 1992; Gullà & Matano, 1994; Gullà & Matano, 1997; Le Pera et al., 2001). In questo contesto, si inserisce il presente lavoro di tesi che si pone come obiettivo quello di illustrare le caratteristiche e gli effetti dei processi di alterazione che hanno luogo nelle rocce cristalline alterate del bordo centro-orientale della Sila. Ricordando che il lavoro è stato finalizzato alla definizione delle relazioni esistenti tra processi di degradazione fisico-chimica ed evoluzione geomorfologica del territorio, anche l’approccio metodologico è stato multidisciplinare. A tale scopo si è fatto ricorso ad un metodo di indagine che tenesse conto degli aspetti geologici, strutturali, geomorfologici ed idrogeologici nell’area in esame. Per verificare la validità e l’efficacia di tali metodi investigativi, ad integrazione delle attività sopra elencate sono state svolte delle analisi specifiche di laboratorio, mirate ad acquisire conoscenze di ulteriore dettaglio, circa la caratterizzazione mineralogico-petrografica e geochimica, nonchè alla definizione di indici correlati al grado di alterazione delle rocce (indici micropetrografici e indici di alterazione geochimica). Infine, per ottenere informazioni utili circa i tempi di esumazione delle rocce e sulla presunta età di inizio dei processi di alterazione che interessano gli ammassi cristallini calabresi (Thomson et al., 1998; Vignaroli et al., 2012; Scarciglia et al.,2005a, 2005b; Scarciglia 2015), è stato avviato uno studio preliminare basato sul metodo di datazione termocronologica (U/Th) / He su apatiti. Tale metodo, utilizzato in genere per la determinazione delle fasi di raffreddamento più avanzate, è stato testato in via sperimentale su cinque campioni per verificarne la validità e l’efficacia, considerando alcuni dei siti in cui precedentemente Vignaroli et al. (2012) avevano ottenuto delle età di raffreddamento delle rocce, mediante l’applicazione del metodo AFT
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    Compositional and textural study of beach sands from active volcanic areas (southern tyrrhenian sea)
    (2018-05-11) Morrone, Consuele; Critelli, Salvatore; De Rose, Rosanna; Le Pera, Emilia; Marsaglia, Kathleen M.
    The main goal of this research focuses on the provenance, compositional and textural investigation of modern sand supplied from volcanic terrains (southern Tyrrhenian sea). This is a contribution to quantify the controls on volcaniclastic sand composition among volcanic areas with different tectonic settings and compositions. Specifically, an important aim of this research is to quantitatively compare the relation between areal distribution, texture and composition of “source” lithotypes – which are the clastic debris producer – with respect to texture and composition of "volcano-derived" sediments. The study area covers the coastal perimeter/stretch of two Italian volcanic provinces in the southern Tyrrhenian sea: Aeolian islands and Campania province. Particular attention has been given to the factors that control the relationships between grain rounding, grain-size, sand composition, texture and source rocks. This research provide a good opportunity to define the provenance signatures of detritus eroded from lavas with different compositions, pyroclastic and minor sedimentary rocks. Different sandy petrofacies for the studied areas of Campania province have been formalized. In order to investigate on provenance, pre-burial processes, composition and texture of modern sand supplied from volcanic terrains, different studies have been carried out through:  Sieving analyses;  Polarizing microscope and Electron Microprobe;  Image analysis (roundness study);  Geographic Information System analysis (SGI calculation). There is a clear differences between Aeolian Islands costal beach sand and Campania coastal beach sand in terms of detritus maturity. Grain-size distribution within Aeolian beach sediment show a tendency towards coarser sand fraction to gravel, whereas Campania coastal samples show a tendency towards medium to fine sand fractions; this indicates a varied physical disintegration of the source rocks. The major components of Aeolian islands and Campania beach sands are monomineralic grains, sedimentary and volcanic lithic fragments with lesser amounts of calcareous bioclasts. Samples from Aeolian islands and Portici Sorrento coastal stretch have an high percentage of volcanic lithic fragments (Lvl > Lvmi> Lvv), whereas samples from Pozzuoli, display an average percentage among Lvl~Lvmi~Lvv. Three different petrofacies have been defined along Campania coastal stretch: sedimentary (Apennines), Vesuvian and Phlegrean fields petrofacies. Stromboli, Vulcano, Alicudi and Filicudi sands have a dual basaltic/shoshonitic and andesitic composition “signatures”. Panarea, Lipari and Salina sands have a wider range of composition “signatures” ranging from basalts to rhyolites. there is evidence that, on Aeolian islands, sand composition does accurately reflect bedrock composition except in the case of source areas dominated by pumice outcrops (e.g. Lipari islands), whereas in more protected and quite beach-environment such as Pozzuoli bay, this grain types (pumice, associated to more evolved [acid] volcanism and then explosive volcanism) have been found and resulted to be texturally more preserved. In the sandy detritus the persistence for the lithic grains is ranked as follows: Lvlblg, Lvmiblgl, Lvvblgl > Lvlbrgl, Lvmibrlgl, Lvvbrgl > Lvlclgl, Lvmiclgl, Lvvclgl > Lvf > Lvlgrgl, Lvmigrgl, Lvvgrgl, pumice. Thus, mafic source rocks will be overestimated and more acid source rocks will be underestimated in the stratigraphic record. New volcanic lithic compounds have been introduced (Lvlgrgl, Lvmigrgl, Lvvgrgl) then who will study the ancient stratigraphic records will know that the Lvlgrgl means dacitic provenance. New discriminating diagrams have been introduced which allow to obtain important information among the volcanic source rocks ranging from basic to acid composition. Lvlblgl, Lvmiblgl, Lvvblgl (1); Lvlbrgl, Lvmibrgl, Lvvbrgl (2); Lvlgrgl, Lvmigrgl, Lvvgrgl (3) can be produced not only by basaltic, andesitic and dacitic source rocks but also by source rocks with the same SiO2 content belonging at different alkaline series (e.g. trachybasalt, shoshonite, latite, trachyandesite, trachydacite, trachyte). Campania samples displaying an higher roundness degree which decrease towards Phlegrean Fields area from north (Volturno river mouth) to south and, show an higher percentage of (3), (4), (5) and (6) roundness category, whereas Aeolian islands samples have an higher percentage of (1) and (2) roundness category. There is a correlation between roundness and geographic location of the Aeolian islands beaches. Sand grains round more efficiently under gentler wave action of the eastern side whereas the more angular grains of the north-western beaches are immediately eroded from the nearby cliffs with null or quite minimal reworking. A new methodological and research approach for roundness degree calculation have been tested by conducting image analysis. By relating GIS, compositional and textural results, it is possible to affirm that lavas source rocks have an higher propensity to create sandy detritus than pyroclastic source rocks. This finding has implications for the stratigraphic record especially for the sandy pumice clasts which could be underrepresented in older volcaniclastic deposits and overrepresented in other detritus size fractions. This actualistic study helps in understanding factors controlling siliciclastic sediment composition and texture, in turn, will help in deciphering major controls on ancient volcaniclastic successions, especially those where volcanic terrains have been totally lost by erosion
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    <> sintomi comportamentali e psicologici nella malattia di Alzheimer: esordio e differenze di genere
    (2018-05-11) Altomari, Natalia; Critelli, Salvatore; Passarino, Giuseppe; Bruni, , Amalia C.
    BPSD have a deep physical and psychological impact on patients affected by any kind of dementing illness and on caregiver in terms of costs and resources and represent an important cause of institutionalization. The aim of the study was to investigate the occurrence of BPSD in a sample of patients with Alzheimer’s disease in three stages: preclinical (TO), from AD onset to five years (T1) and for five years onwards (T2). Furthermore, possible differences between men and women and Early and Late Onset Alzheimer’s disease (EOAD and LOAD) have been analyzed. 1925 medical records of AD patients, diagnosed with NINCDS-ADRDA, criteria have been examined from the digital database of the Regional Neurogenetics Center (ASP-CZ). Symptoms have been extracted from Neuropsychiatric Inventory (NPI) and from a check list of BPSD for internal use for as long as BPSD have been observed(apathy, irritability, depression, anxiety, delusions, hallucinations, aggression, agitation, disinhibition, affective lability, wandering, sleep disorders and eating disorders). At least one BPSD was detected in 90,4% of the sample. The most represented symptoms were apathy (57.4%), irritability/affective lability (50.5%) and agitation/aggression (42.3%), the last two were presented especially in men (p = 0.000). Most of BPSD are distributed between the fourth and fifth year of illness. According to gender, disinhibition appears significantly later in women and according to onset all BPSD manifest significantly later in patients with EOAD. Concerning differences between EOAD and LOAD patients, sleep disorders characterize EOAD in preclinical stage (p=0.022). Depression (p=0.017) is predominant in EOAD at T1, while LOAD presents with more irritability/affective lability (p=0.000), agitation/aggression (p=0.001) and sleep disorders (p=0.000). A considerable number of EOAD patients still develop BPSD in the advanced stage (T2). As regard gender, considering BPSD timing, depression characterizes women in preclinical stage (T0) (p=0.01). At T1 men show disinhibition (p=0.002) irritability/affective lability (p=0.000), sleep disorders (p=0.03), agitation/aggression (p=0.000) while women exibit greater anxiety (p=0.027) and depression (p=0.000). No gender differences have been evidenced in T2. Behavioral and Psychological Symptoms in our cohort demonstrates, in agreement with the literature how AD is not only “a cognitive” disease. Interestingly, a number of signs of behavioral changes appear before AD onset. The identification of these “red flags” of AD can be important and significant for the early detection of the disease. Predominance of affective pattern in women and aggressivity in men suggests that gender differences can be related to a brain’s pathophysiological diversity. Therefore, a strategic and adaptive management of these symptoms is always necessary to early diagnose, cure and care patients with this devastating brain disorder
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    Relazione tra weathering e tettonica nei processi morfoevolutivi di una porzione del versante occidentale del massiccio della Sila, Calabria
    (2019-05-21) Biondino, Deborah; Critelli, Salvatore; Muto, Francesco; Borrelli, Luigi; Tripodi, Vincenzo
    Il weathering attraverso i suoi processi di degradazione chimico-fisica porta al disfacimento delle rocce cristalline con conseguente formazione di una coltre più o meno spessa di roccia alterata, a grado di alterazione variabile sulla base delle trasformazioni subite dalle caratteristiche originarie del bedrock inalterato, che condiziona la stabilità e l’evoluzione dei versanti in cui affiorano gli ammassi rocciosi (Deere & Patton 1971; Ietto, 1975; Fookes, 1978; Hencher et al. 1984; Brand 1985; Critelli et al., 1990,1991; Cascini et al., 1992; Gullà et al. 2004; Borrelli et al. 2007,2014,2015). Inoltre, la dinamica evolutiva dei versanti risulta fortemente influenzata dai fenomeni di erosione, dai movimenti in massa e dalla presenza di strutture tettoniche e/o fratturazione. La tettonica, infatti, oltre a dare un notevole contributo allo sviluppo dei processi alterativi attraverso il disfacimento meccanico delle rocce lungo i piani di discontinuità e il possibile trasferimento delle acque meteoriche in profondità secondo direzioni preferenziali, svolge un ruolo rilevante nell’evoluzione dei fenomeni franosi con controllo sui cinematismi che li caratterizzano. Tali fenomeni di instabilità, non facilmente riconoscibili poiché attuatisi in tempi brevi e senza segni premonitori chiaramente identificabili, diffusamente intaccano, con le più svariate fenomenologie franose, le rocce cristalline intensamente alterate che costituiscono l’ossatura del Massiccio della Sila, e più in generale, la maggior parte dei massicci calabresi con una presenza di circa il 25% dell’intero territorio regionale (Guzzetta, 1974; Ietto, 1975; Cascini et al., 1988, 1992). Nell’analisi di degradazione delle rocce cristalline calabresi bisogna tener conto della storia geologica complessa ed estremamente attiva che rende la Calabria un territorio unico ma presentante i principali fattori di predisposizione ai fenomeni franosi. Tale passato geologico ha visto, nel tempo, il susseguirsi di diverse fasi tettoniche che hanno portato alla strutturazione del massiccio silano fino alla conformazione attuale, con i derivanti stati di fratturazione e fagliazione, nonché il verificarsi dei processi di weathering che hanno intaccato le rocce fin dalle prime fasi del rapido sollevamento di detto edificio cristallino, con produzione di un profondo mantello di alterazione dell’ordine di decine di metri preservato nel tempo ed attualmente esposto a seguito dell’intensa erosione verificatasi nella regione (Guzzetta, 1974). I volumi di roccia alterata che si estendono dalla roccia madre “fresca” fino alla superficie topografica e per definizione corrispondono al profilo di alterazione, variano in profondità nel territorio calabrese sotto l’influenza di molteplici fattori interagenti (clima, tempo, tettonica e rilievo) che ne controllano l’età o determinano il ringiovanimento dei fronti stessi (Scarciglia, 2015). Determinare l’età e l’origine della coltre alteritica in un contesto che vede l’interazione Ad integrazione dei dati ottenuti, una successiva fase sviluppatasi in laboratorio, attraverso appropriate analisi minero-petrografiche e geochimiche dei campioni appartenenti alle diverse classi di alterazioni, ha condotto alla caratterizzazione del grado di alterazione in profondità ed ha determinato, inoltre, la possibilità di creare una modellazione predittiva che permette di valutare l’evoluzione mineralogica al procedere del weathering, ovvero le modalità e le principali trasformazioni (fase primarie disciolte e fase secondarie precipitate) che interessano i litotipi gneissici durante l’interazione acqua- roccia. I risultati delle indagini hanno consentito di affermare come i diversi aspetti del weathering analizzati siano connessi tra di loro, e le relazioni esistenti tra caratteristiche geologiche, strutturali, minero-petrografiche del weathering si riflettono sulle proprietà fisico-meccaniche dei terreni, sul loro comportamento reologico, concorrendo ad influenzare lo sviluppo dei fenomeni franosi. La metodologia applicata può rappresentare uno strumento utile per la pianificazione dell'uso del territorio e può proficuamente consentire di caratterizzare le frane e di valutare in modo quantitativo il rischio ad esse connesso, nell’ampio quadro conoscitivo delineato che ha fornito uno scenario preliminare delle possibili problematiche che possono insorgere per la pianificazione territoriale e per la realizzazione di opere rilevanti. Dunque, le indicazioni esposte nel presente lavoro consentono di indirizzare e programmare in maniera efficace ed incisiva gli approfondimenti di studio ed indagini necessari alla progettazione, realizzazione e gestione di specifici interventi.
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    Geological and structural evolution of tectonically active areas of the central Calabria Arc
    (2016-03-04) Brutto, Fabrizio; Pantano, Pietro; Muto, Francesco; Loreto, Maria Filomena; Critelli, Salvatore
    The Catanzaro Trough is a Neogene-Quaternary basin developed between the Serre and the Sila Massif, filled by up to 2000 m of Upper Miocene to Quaternary sedimentary succession, belonging to the central Calabrian Arc and extended from offshore, Sant’Eufemia Basin (SE Tyrrhenian Sea), to the onshore, Catanzaro Basin. By joining on land geo-structural with marine geophysical data, we performed a detailed analysis of processes that during last 5 My have controlled the evolution of western portion of the Catanzaro Trough. The fieldwork study, focused on the onshore area, has allowed to acquire more than 700 fault planes, classified on the base of kinematics and fault directions, whereas the geophysical data (sub-bottom, multi- and mono-channel seismic profiles), coming from some scientific cruises within the Sant’Eufemia Gulf (SE Tyrrhenian Sea), gave us the opportunity to reconstruct the tectono-stratigraphic evolution of the offshore area. The combination amongst abrupt sea level changes, transpressional and trans/extensional tectonics and back-arc Tyrrhenian subsidence during SE-drifting of Calabrian Arc controlled sedimentary basin hosted by the Catanzaro Trough, as the result we have recognized three tectonic events formed in the Upper Miocene- Zanclean, Piacezian-Lower Pleistocene, and Middle-Upper Pleistocene. The data analysis provide information about stratigraphy and tectonics in the strata and also give some indication of the tectono-stratigraphic architecture. Sedimentary basin, in fact, looks to be mainly controlled by the activity of NW–SE and NE–SW oriented fault systems. The NW-SE oriented faults showing strike slip and oblique kinematics can be considered responsible for the opening of a WNW–ESE paleo-strait connecting the Tyrrhenian Sea with the Ionian Sea during multi-phases tectonics that have acted in the study area since Miocene. The integrated geo-structural and geophysical data show a change from left-lateral to right-lateral kinematics during Piacezian-Lower Pleistocene, as the result of a change of the stress field. Since Middle Pleistocene, the study area experienced an extensional phase, WNWESE oriented, controlled mainly by NE-SW and subordinately N-S oriented normal faults, which split obliquely the western Catanzaro Trough, producing up-faulted and downfaulted blocks, arranged as graben-type systems, extending from onshore to offshore area. In agreement with and Jacques et al., (2001) and Presti et al., (2013), the NE-SW and NS trend normal faults play a relevant role as part of recent seismotectonic processes controlling the Late Quaternary geodynamic of the central Calabrian Arc, representing the source of the main destructive earthquakes occurred in the area. Thanks to these multidisciplinary approach we are able to provide a more reliable and detailed structural frame of the central Calabria segment, providing new elements about recent activity of faults, and giving a further contribution for the seismogenetic potential assessment of an area historically considered with the highest earthquake and tsunami risk throughout Italy.
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