Dissertations / Theses on the topic 'Northern Apennines'

For its particular position and the complex geological history, the Northern Apennines has been considered as a natural laboratory to apply several kinds of investigations. By the way, it is complicated to joint all the knowledge about the Northern Apennines in a unique picture that explains the structural and geological emplacement that produced it. The main goal of this thesis is to put together all information on the deformation - in the crust and at depth - of this region and to describe a geodynamical model that takes account of it. To do so, we have analyzed the pattern of deformation in the crust and in the mantle. In both cases the deformation has been studied using always information recovered from earthquakes, although using different techniques. In particular the shallower deformation has been studied using seismic moment tensors information. For our purpose we used the methods described in Arvidsson and Ekstrom (1998) that allowing the use in the inversion of surface waves [and not only of the body waves as the Centroid Moment Tensor (Dziewonski et al., 1981) one] allow to determine seismic source parameters for earthquakes with magnitude as small as 4.0. We applied this tool in the Northern Apennines and through this activity we have built up the Italian CMT dataset (Pondrelli et al., 2006) and the pattern of seismic deformation using the Kostrov (1974) method on a regular grid of 0.25 degree cells. We obtained a map of lateral variations of the pattern of seismic deformation on different layers of depth, taking into account the fact that shallow earthquakes (within 15 km of depth) in the region occur everywhere while most of events with a deeper hypocenter (15-40 km) occur only in the outer part of the belt, on the Adriatic side. For the analysis of the deep deformation, i.e. that occurred in the mantle, we used the anisotropy information characterizing the structure below the Northern Apennines. The anisotropy is an earth properties that in the crust is due to the presence of aligned fluid filled cracks or alternating isotropic layers with different elastic properties while in the mantle the most important cause of seismic anisotropy is the lattice preferred orientation (LPO) of the mantle minerals as the olivine. This last is a highly anisotropic mineral and tends to align its fast crystallographic axes (a-axis) parallel to the astenospheric flow as a response to finite strain induced by geodynamic processes. The seismic anisotropy pattern of a region is measured utilizing the shear wave splitting phenomenon (that is the seismological analogue to optical birefringence). Here, to do so, we apply on teleseismic earthquakes recorded on stations located in the study region, the Sileny and Plomerova (1996) approach. The results are analyzed on the basis of their lateral and vertical variations to better define the earth structure beneath Northern Apennines. We find different anisotropic domains, a Tuscany and an Adria one, with a pattern of seismic anisotropy which laterally varies in a similar way respect to the seismic deformation. Moreover, beneath the Adriatic region the distribution of the splitting parameters is so complex to request an appropriate analysis. Therefore we applied on our data the code of Menke and Levin (2003) which allows to look for different models of structures with multilayer anisotropy. We obtained that the structure beneath the Po Plain is probably even more complicated than expected. On the basis of the results obtained for this thesis, added with those from previous works, we suggest that slab roll-back, which created the Apennines and opened the Tyrrhenian Sea, evolved in the north boundary of Northern Apennines in a different way from its southern part. In particular, the trench retreat developed primarily south of our study region, with an eastward roll-back. In the northern portion of the orogen, after a first stage during which the retreat was perpendicular to the trench, it became oblique with respect to the structure.

For its particular position and the complex geological history, the Northern Apennines has been considered as a natural laboratory to apply several kinds of investigations. By the way, it is complicated to joint all the knowledge about the Northern Apennines in a unique picture that explains the structural and geological emplacement that produced it. The main goal of this thesis is to put together all information on the deformation - in the crust and at depth - of this region and to describe a geodynamical model that takes account of it. To do so, we have analyzed the pattern of deformation in the crust and in the mantle. In both cases the deformation has been studied using always information recovered from earthquakes, although using different techniques. In particular the shallower deformation has been studied using seismic moment tensors information. For our purpose we used the methods described in Arvidsson and Ekstrom (1998) that allowing the use in the inversion of surface waves [and not only of the body waves as the Centroid Moment Tensor (Dziewonski et al., 1981) one] allow to determine seismic source parameters for earthquakes with magnitude as small as 4.0. We applied this tool in the Northern Apennines and through this activity we have built up the Italian CMT dataset (Pondrelli et al., 2006) and the pattern of seismic deformation using the Kostrov (1974) method on a regular grid of 0.25 degree cells. We obtained a map of lateral variations of the pattern of seismic deformation on different layers of depth, taking into account the fact that shallow earthquakes (within 15 km of depth) in the region occur everywhere while most of events with a deeper hypocenter (15-40 km) occur only in the outer part of the belt, on the Adriatic side. For the analysis of the deep deformation, i.e. that occurred in the mantle, we used the anisotropy information characterizing the structure below the Northern Apennines. The anisotropy is an earth properties that in the crust is due to the presence of aligned fluid filled cracks or alternating isotropic layers with different elastic properties while in the mantle the most important cause of seismic anisotropy is the lattice preferred orientation (LPO) of the mantle minerals as the olivine. This last is a highly anisotropic mineral and tends to align its fast crystallographic axes (a-axis) parallel to the astenospheric flow as a response to finite strain induced by geodynamic processes. The seismic anisotropy pattern of a region is measured utilizing the shear wave splitting phenomenon (that is the seismological analogue to optical birefringence). Here, to do so, we apply on teleseismic earthquakes recorded on stations located in the study region, the Sileny and Plomerova (1996) approach. The results are analyzed on the basis of their lateral and vertical variations to better define the earth structure beneath Northern Apennines. We find different anisotropic domains, a Tuscany and an Adria one, with a pattern of seismic anisotropy which laterally varies in a similar way respect to the seismic deformation. Moreover, beneath the Adriatic region the distribution of the splitting parameters is so complex to request an appropriate analysis. Therefore we applied on our data the code of Menke and Levin (2003) which allows to look for different models of structures with multilayer anisotropy. We obtained that the structure beneath the Po Plain is probably even more complicated than expected. On the basis of the results obtained for this thesis, added with those from previous works, we suggest that slab roll-back, which created the Apennines and opened the Tyrrhenian Sea, evolved in the north boundary of Northern Apennines in a different way from its southern part. In particular, the trench retreat developed primarily south of our study region, with an eastward roll-back. In the northern portion of the orogen, after a first stage during which the retreat was perpendicular to the trench, it became oblique with respect to the structure.

The Northern Apennines (NA) chain is the expression of the active plate margin between Europe and Adria. Given the low convergence rates and the moderate seismic activity, ambiguities still occur in defining a seismotectonic framework and many different scenarios have been proposed for the mountain front evolution. Differently from older models that indicate the mountain front as an active thrust at the surface, a recently proposed scenario describes the latter as the frontal limb of a long-wavelength fold (> 150 km) formed by a thrust fault tipped around 17 km at depth, and considered as the active subduction boundary. East of Bologna, this frontal limb is remarkably very straight and its surface is riddled with small, but pervasive high- angle normal faults. However, west of Bologna, some recesses are visible along strike of the mountain front: these perturbations seem due to the presence of shorter wavelength (15 to 25 km along strike) structures showing both NE and NW-vergence. The Pleistocene activity of these structures was already suggested, but not quantitative reconstructions are available in literature. This research investigates the tectonic geomorphology of the NA mountain front with the specific aim to quantify active deformations and infer possible deep causes of both short- and long-wavelength structures. This study documents the presence of a network of active extensional faults, in the foothills south and east of Bologna. For these structures, the strain rate has been measured to find a constant throw-to-length relationship and the slip rates have been compared with measured rates of erosion. Fluvial geomorphology and quantitative analysis of the topography document in detail the active tectonics of two growing domal structures (Castelvetro - Vignola foothills and the Ghiardo plateau) embedded in the mountain front west of Bologna. Here, tilting and river incision rates (interpreted as that long-term uplift rates) have been measured respectively at the mountain front and in the Enza and Panaro valleys, using a well defined stratigraphy of Pleistocene to Holocene river terraces and alluvial fan deposits as growth strata, and seismic reflection profiles relationships. The geometry and uplift rates of the anticlines constrain a simple trishear fault propagation folding model that inverts for blind thrust ramp depth, dip, and slip. Topographic swath profiles and the steepness index of river longitudinal profiles that traverse the anti- clines are consistent with stratigraphy, structures, aquifer geometry, and seismic reflection profiles. Available focal mechanisms of earthquakes with magnitude between Mw 4.1 to 5.4, obtained from a dataset of the instrumental seismicity for the last 30 years, evidence a clear vertical separation at around 15 km between shallow extensional and deeper compressional hypocenters along the mountain front and adjacent foothills. In summary, the studied anticlines appear to grow at rates slower than the growing rate of the longer- wavelength structure that defines the mountain front of the NA. The domal structures show evidences of NW-verging deformation and reactivations of older (late Neogene) thrusts. The reconstructed river incision rates together with rates coming from several other rivers along a 250 km wide stretch of the NA mountain front and recently available in the literature, all indicate a general increase from Middle to Late Pleistocene. This suggests focusing of deformation along a deep structure, as confirmed by the deep compressional seismicity. The maximum rate is however not constant along the mountain front, but varies from 0.2 mm/yr in the west to more than 2.2 mm/yr in the eastern sector, suggesting a similar (eastward-increasing) trend of the apenninic subduction.

The Northern Apennines (NA) chain is the expression of the active plate margin between Europe and Adria. Given the low convergence rates and the moderate seismic activity, ambiguities still occur in defining a seismotectonic framework and many different scenarios have been proposed for the mountain front evolution. Differently from older models that indicate the mountain front as an active thrust at the surface, a recently proposed scenario describes the latter as the frontal limb of a long-wavelength fold (> 150 km) formed by a thrust fault tipped around 17 km at depth, and considered as the active subduction boundary. East of Bologna, this frontal limb is remarkably very straight and its surface is riddled with small, but pervasive high- angle normal faults. However, west of Bologna, some recesses are visible along strike of the mountain front: these perturbations seem due to the presence of shorter wavelength (15 to 25 km along strike) structures showing both NE and NW-vergence. The Pleistocene activity of these structures was already suggested, but not quantitative reconstructions are available in literature. This research investigates the tectonic geomorphology of the NA mountain front with the specific aim to quantify active deformations and infer possible deep causes of both short- and long-wavelength structures. This study documents the presence of a network of active extensional faults, in the foothills south and east of Bologna. For these structures, the strain rate has been measured to find a constant throw-to-length relationship and the slip rates have been compared with measured rates of erosion. Fluvial geomorphology and quantitative analysis of the topography document in detail the active tectonics of two growing domal structures (Castelvetro - Vignola foothills and the Ghiardo plateau) embedded in the mountain front west of Bologna. Here, tilting and river incision rates (interpreted as that long-term uplift rates) have been measured respectively at the mountain front and in the Enza and Panaro valleys, using a well defined stratigraphy of Pleistocene to Holocene river terraces and alluvial fan deposits as growth strata, and seismic reflection profiles relationships. The geometry and uplift rates of the anticlines constrain a simple trishear fault propagation folding model that inverts for blind thrust ramp depth, dip, and slip. Topographic swath profiles and the steepness index of river longitudinal profiles that traverse the anti- clines are consistent with stratigraphy, structures, aquifer geometry, and seismic reflection profiles. Available focal mechanisms of earthquakes with magnitude between Mw 4.1 to 5.4, obtained from a dataset of the instrumental seismicity for the last 30 years, evidence a clear vertical separation at around 15 km between shallow extensional and deeper compressional hypocenters along the mountain front and adjacent foothills. In summary, the studied anticlines appear to grow at rates slower than the growing rate of the longer- wavelength structure that defines the mountain front of the NA. The domal structures show evidences of NW-verging deformation and reactivations of older (late Neogene) thrusts. The reconstructed river incision rates together with rates coming from several other rivers along a 250 km wide stretch of the NA mountain front and recently available in the literature, all indicate a general increase from Middle to Late Pleistocene. This suggests focusing of deformation along a deep structure, as confirmed by the deep compressional seismicity. The maximum rate is however not constant along the mountain front, but varies from 0.2 mm/yr in the west to more than 2.2 mm/yr in the eastern sector, suggesting a similar (eastward-increasing) trend of the apenninic subduction.

The objective of this study is to provide an innovative methodology for the estimation of climate change impacts on groundwater resources. This methodology has been applied to the Tresinaro stream catchment (147 km2) in the northern Apennines (Italy), and to the main water source of the stream, the Mulino delle Vene springs (Carpineti, Reggio Emilia province). These springs outflow from a fractured aquifer hosted in a sandstone plateau, and the mean discharge is 96.8 l/s. Firstly, some finite elements models of the fractured aquifer feeding the Mulino delle Vene springs have been developed, with the codes FEFLOW and TRANSIN, in order to investigate the groundwater flow system. In particular, some sensitivity analyses and transient state simulations have been carried out, and a range of calibrated conductivity values for the fractured rock masses (between 1.16 x 10-4 m/s and 1.16 x 10-7 m/s) has been identified. Moreover, a physically based surface-subsurface flow model has been developed for the Tresinaro stream catchment with the finite elements code HydroGeoSphere. In the second place, some rainfall-runoff models of the Mulino delle Vene springs have been built and calibrated on the daily springs discharge data. Then, the calibrated and validated models have been combined with climate change scenarios from five Regional Climate Models. Considering the results of this study, it is very likely that, in the next future, groundwater flow rates of the Mulino delle Vene springs will decrease, especially during the low flow period, exacerbating the water stress condition in the area (e.g. maximum discharge is likely to decrease by the 26.3% in September). The results of this analysis represent a first answer to the lack of researches in the field of climate change and groundwater in Italy. The developed methodology can be easily applied to other areas.

This PhD thesis focuses on the validation of an objective method to define paleocurrent directions in turbiditic systems: the anisotropy of magnetic susceptibility (AMS). The final purpose of this study is to calibrate paleocurrent directions estimated with this geophysical method to directions estimated from classic sedimentological indicators, and therefore verify the applicability of this method to cases where sedimentological paleocurrent indicators are absent such as in drill cores. Two selected turbiditic units outcropping in the northern Apennines, the Marnoso Arenacea Formation (Miocene, northern Apennines) and on the Castagnola Formation (Oligo-Miocene, Tertiary Piedmont Basin), were investigated. These basins have different depositional settings: the Marnoso Arenacea Formation filled a foredeep basin nearly 200 km long and 60 km wide, whereas the Castagnola Formation filled an episutural basin 6 km long and 4 km wide. AMS analyses were successfully applied to both formations on a total of 853 samples taken in a wide range of depositional intervals selected by means of detailed sedimentological analyses, and were successively cross-validated by direct estimates of flow directions from sedimentological indicators (ripple marks, flute marks, etc.). In the Marnoso Arenacea Formation, a robust correlation between magnetic fabric and paleocurrent directions obtained from sedimentological indicators was found in massive, parallel-laminated, and cross-laminated sandstones. These depositional intervals show well-clustered AMS data with an overall flow-aligned fabric. Instead, highly dispersed AMS fabrics are apparently common in convoluted and undulated sandstones as well as in debrites, suggesting depositional processes that partially prevented grains’ orientation (e.g., en masse freezing) or post-depositional processes that disrupted the original current-induced fabric (e.g., post-depositional dewatering). AMS fabrics typical of deposition in standing water was observed in the hemipelagites of the Castagnola Formation. Instead, in the fine-grained sediments of the Marnoso Arenacea Formation (White Marlstone beds), an AMS fabric interpreted as current-induced was observed and interpreted as due to muddy contourites. The study on the Castagnola Formation was carried out primarily to evaluate the effects of basin confinement on turbidity flow dynamics. In this small, confined turbidite system, we observed a strong correlation between magnetic fabric and bed-thickness distribution whereby beds thicker than ~1.20 m show high magnetic fabric variability and maximum susceptibility axes dispersion, whereas beds thinner than ~1.20 m show better developed magnetic fabrics with maximum susceptibility axes oriented consistently parallel to the mean paleoflow direction from flute casts. We believe that ~1.20 m represents a thickness threshold separating large flows that covered the entire basin floor interacting in a complex fashion with the basin’s margins from small volume flows that did not interact with the basin’s margins and produced better-defined flow-aligned AMS fabrics. Potential future developments of this thesis are: (1) deepening of our understanding on the relationships between grains’ orientations and magnetic minerals that contribute to the AMS signal by means of textural analyses, neutron diffraction and x-ray tomography. Preliminary results indicate that paramagnetic muscovite principally controls the observed current induced AMS fabric; (2) testing the AMS method on drill core samples, where flow marks (i.e., flute casts) are either absent or non-observable.

Thrust fault-related folds in carbonate rocks are characterized by deformation accommodated by different structures, such as joints, faults, pressure solution seams, and deformation bands. Defining the development of fracture systems related to the folding process is significant both for theoretical and practical purposes. Fracture systems are useful constrains in order to understand the kinematical evolution of the fold. Furthermore, understanding the relationships between folding and fracturing provides a noteworthy contribution for reconstructing the geodynamic and the structural evolution of the studied area. Moreover, as fold-related fractures influence fluid flow through rocks, fracture systems are relevant for energy production (geothermal studies, methane and CO2 , storage and hydrocarbon exploration), environmental and social issues (pollutant distribution, aquifer characterization). The PhD project shows results of a study carried out in a multilayer carbonate anticline characterized by different mechanical properties. The aim of this study is to understand the factors which influence the fracture formation and to define their temporal sequence during the folding process. The studied are is located in the Cingoli anticline (Northern Apennines), which is characterized by a pelagic multilayer characterized by sequences with different mechanical stratigraphies. A multi-scale analysis has been made in several outcrops located in different structural positions. This project shows that the conceptual sketches proposed in literature and the strain distribution models outline well the geometrical orientation of most of the set of fractures observed in the Cingoli anticline. On the other hand, the present work suggests the relevance of the mechanical stratigraphy in particular controlling the type of fractures formed (e.g. pressure solution seams, joints or shear fractures) and their subsequent evolution. Through a multi-scale analysis, and on the basis of the temporal relationship between fracture sets and their orientation respect layering, I also suggest a conceptual model for fracture systems formation.
Le anticlinali carbonatiche presentano un’intensa fratturazione indotta dalla deformazione durante il piegamento. Caratterizzare e comprendere lo sviluppo dei sistemi di fratture collegati al processo plicativo risulta essere di notevole interesse sia da un punto di vista scientifico che applicativo. I sistemi di fratture forniscono un contributo fondamentale per la comprensione dell’evoluzione cinematica della pieghe, inoltre, la comprensione delle relazioni tra sistemi di fratture e pieghe può contribuire a definire l'evoluzione strutturale dell'area di studio. Da un punto di vista applicativo è ormai noto come i sistemi di fratture incidono enormemente sulla circolazione dei fluidi. Di conseguenza la loro definizione trova un'applicazione importante nel settore energetico (flussi geotermici, stoccaggio gas e CO2, esplorazione petrolifera), ambientale (dispersione di inquinanti nel sottosuolo), e sociale (caratterizzazione degli acquiferi ecc.). La tesi di Dottorato presenta uno studio sull’analisi e la caratterizzazione di sistemi di fratture in un’anticlinale carbonatica caratterizzata da un multistrato con diverse caratteristiche meccaniche. Il progetto di Dottorato si pone l’obiettivo di comprendere i fattori che maggiormente influenzano le proprietà dei sistemi di fratture e di definire la loro evoluzione nel tempo. A tal fine è stata analizzata l’anticlinale di Cingoli (Appennino settentrionale) che espone una serie di interessanti affioramenti in calcari pelagici. Attraverso analisi a diverse scale di osservazione sono stati quindi caratterizzati i sistemi di fratture in affioramenti posizionati lungo tutta l’anticlinale e in diverse posizioni strutturali. Nel lavoro è stato osservato e discusso come la posizione strutturale e soprattutto la stratigrafia meccanica influiscono sulla formazione dei sistemi di fratture. In particolare è stato osservato come i modelli proposti in letteratura sintetizzano e schematizzano bene l’assetto geometrico di alcune fratture osservate a Cingoli. In questo lavoro, però, si è evidenziato come la stratigrafia meccanica ha un ruolo decisivo soprattutto per quanto riguarda la tipologia meccanica di fratture.

Thrust fault-related folds in carbonate rocks are characterized by deformation accommodated by different structures, such as joints, faults, pressure solution seams, and deformation bands. Defining the development of fracture systems related to the folding process is significant both for theoretical and practical purposes. Fracture systems are useful constrains in order to understand the kinematical evolution of the fold. Furthermore, understanding the relationships between folding and fracturing provides a noteworthy contribution for reconstructing the geodynamic and the structural evolution of the studied area. Moreover, as fold-related fractures influence fluid flow through rocks, fracture systems are relevant for energy production (geothermal studies, methane and CO2 , storage and hydrocarbon exploration), environmental and social issues (pollutant distribution, aquifer characterization). The PhD project shows results of a study carried out in a multilayer carbonate anticline characterized by different mechanical properties. The aim of this study is to understand the factors which influence the fracture formation and to define their temporal sequence during the folding process. The studied are is located in the Cingoli anticline (Northern Apennines), which is characterized by a pelagic multilayer characterized by sequences with different mechanical stratigraphies. A multi-scale analysis has been made in several outcrops located in different structural positions. This project shows that the conceptual sketches proposed in literature and the strain distribution models outline well the geometrical orientation of most of the set of fractures observed in the Cingoli anticline. On the other hand, the present work suggests the relevance of the mechanical stratigraphy in particular controlling the type of fractures formed (e.g. pressure solution seams, joints or shear fractures) and their subsequent evolution. Through a multi-scale analysis, and on the basis of the temporal relationship between fracture sets and their orientation respect layering, I also suggest a conceptual model for fracture systems formation.
Le anticlinali carbonatiche presentano un’intensa fratturazione indotta dalla deformazione durante il piegamento. Caratterizzare e comprendere lo sviluppo dei sistemi di fratture collegati al processo plicativo risulta essere di notevole interesse sia da un punto di vista scientifico che applicativo. I sistemi di fratture forniscono un contributo fondamentale per la comprensione dell’evoluzione cinematica della pieghe, inoltre, la comprensione delle relazioni tra sistemi di fratture e pieghe può contribuire a definire l'evoluzione strutturale dell'area di studio. Da un punto di vista applicativo è ormai noto come i sistemi di fratture incidono enormemente sulla circolazione dei fluidi. Di conseguenza la loro definizione trova un'applicazione importante nel settore energetico (flussi geotermici, stoccaggio gas e CO2, esplorazione petrolifera), ambientale (dispersione di inquinanti nel sottosuolo), e sociale (caratterizzazione degli acquiferi ecc.). La tesi di Dottorato presenta uno studio sull’analisi e la caratterizzazione di sistemi di fratture in un’anticlinale carbonatica caratterizzata da un multistrato con diverse caratteristiche meccaniche. Il progetto di Dottorato si pone l’obiettivo di comprendere i fattori che maggiormente influenzano le proprietà dei sistemi di fratture e di definire la loro evoluzione nel tempo. A tal fine è stata analizzata l’anticlinale di Cingoli (Appennino settentrionale) che espone una serie di interessanti affioramenti in calcari pelagici. Attraverso analisi a diverse scale di osservazione sono stati quindi caratterizzati i sistemi di fratture in affioramenti posizionati lungo tutta l’anticlinale e in diverse posizioni strutturali. Nel lavoro è stato osservato e discusso come la posizione strutturale e soprattutto la stratigrafia meccanica influiscono sulla formazione dei sistemi di fratture. In particolare è stato osservato come i modelli proposti in letteratura sintetizzano e schematizzano bene l’assetto geometrico di alcune fratture osservate a Cingoli. In questo lavoro, però, si è evidenziato come la stratigrafia meccanica ha un ruolo decisivo soprattutto per quanto riguarda la tipologia meccanica di fratture.

L'analisi delle componenti indipendenti (Independent Component Analysis, ICA) è una tecnica di statistica multivariata che consente di scomporre un segnale complesso in un certo numero di componenti, tra loro statisticamente indipendenti, che rappresentano le principali sorgenti di quel segnale. La tecnica ICA è stata applicata a serie temporali di spostamento GPS relative a 30 stazioni localizzate nell'Alta Valle del Tevere, nell'Appennino settentrionale. In quest'area, una faglia normale a basso angolo di immersione (circa 15°), faglia Altotiberina (Altotiberina fault, ATF), risulta attiva e responsabile di microsismicità (ML< 3), nonostante la teoria di Anderson sulla fagliazione affermi che non dovrebbe esserci scorrimento su faglie normali di questo tipo. L'interesse per l'ATF è inoltre dovuto al suo potenziale sismogenetico: un evento che dovesse attivare l'intera faglia (lunga circa 70 km) avrebbe infatti magnitudo intorno a 7. Per questo motivo la zona è monitorata da reti multiparametriche (sismiche, geodetiche, geochimiche) che registrano dati in maniera continuativa, rendendo possibile l’individuazione anche di piccoli segnali di deformazione transiente. Applicando la ICA alle serie temporali GPS si ottiene una scomposizione del segnale in 4 componenti indipendenti. L’analisi di queste componenti ha portato all’individuazione di correlazioni con serie temporali di piovosità, temperatura e sismicità. Una delle componenti, che presenta un segnale transiente di origine tettonica, è stata poi invertita per determinare la distribuzione dello scorrimento su piani di faglia noti. Il momento sismico associato allo scorrimento sulle faglie risulta maggiore del momento sismico associato ai terremoti registrati nell'area, suggerendo quindi che una parte dello scorrimento sia dovuto a movimenti asismici.

Geochemical mapping is a valuable tool for the control of territory that can be used not only in the identification of mineral resources and geological, agricultural and forestry studies but also in the monitoring of natural resources by giving solutions to environmental and economic problems. Stream sediments are widely used in the sampling campaigns carried out by the world's governments and research groups for their characteristics of broad representativeness of rocks and soils, for ease of sampling and for the possibility to conduct very detailed sampling In this context, the environmental role of stream sediments provides a good basis for the implementation of environmental management measures, in fact the composition of river sediments is an important factor in understanding the complex dynamics that develop within catchment basins therefore they represent a critical environmental compartment: they can persistently incorporate pollutants after a process of contamination and release into the biosphere if the environmental conditions change. It is essential to determine whether the concentrations of certain elements, in particular heavy metals, can be the result of natural erosion of rocks containing high concentrations of specific elements or are generated as residues of human activities related to a certain study area. This PhD thesis aims to extract from an extensive database on stream sediments of the Romagna rivers the widest spectrum of informations. The study involved low and high order stream in the mountain and hilly area, but also the sediments of the floodplain area, where intensive agriculture is active. The geochemical signals recorded by the stream sediments will be interpreted in order to reconstruct the natural variability related to bedrock and soil contribution, the effects of the river dynamics, the anomalous sites, and with the calculation of background values be able to evaluate their level of degradation and predict the environmental risk.

Geochemical mapping is a valuable tool for the control of territory that can be used not only in the identification of mineral resources and geological, agricultural and forestry studies but also in the monitoring of natural resources by giving solutions to environmental and economic problems. Stream sediments are widely used in the sampling campaigns carried out by the world's governments and research groups for their characteristics of broad representativeness of rocks and soils, for ease of sampling and for the possibility to conduct very detailed sampling In this context, the environmental role of stream sediments provides a good basis for the implementation of environmental management measures, in fact the composition of river sediments is an important factor in understanding the complex dynamics that develop within catchment basins therefore they represent a critical environmental compartment: they can persistently incorporate pollutants after a process of contamination and release into the biosphere if the environmental conditions change. It is essential to determine whether the concentrations of certain elements, in particular heavy metals, can be the result of natural erosion of rocks containing high concentrations of specific elements or are generated as residues of human activities related to a certain study area. This PhD thesis aims to extract from an extensive database on stream sediments of the Romagna rivers the widest spectrum of informations. The study involved low and high order stream in the mountain and hilly area, but also the sediments of the floodplain area, where intensive agriculture is active. The geochemical signals recorded by the stream sediments will be interpreted in order to reconstruct the natural variability related to bedrock and soil contribution, the effects of the river dynamics, the anomalous sites, and with the calculation of background values be able to evaluate their level of degradation and predict the environmental risk.

Landslide hazard and risk are growing as a consequence of climate change and demographic pressure. Land‐use planning represents a powerful tool to manage this socio‐economic problem and build sustainable and landslide resilient communities. Landslide inventory maps are a cornerstone of land‐use planning and, consequently, their quality assessment represents a burning issue. This work aimed to define the quality parameters of a landslide inventory and assess its spatial and temporal accuracy with regard to its possible applications to land‐use planning. In this sense, I proceeded according to a two‐steps approach. An overall assessment of the accuracy of data geographic positioning was performed on four case study sites located in the Italian Northern Apennines. The quantification of the overall spatial and temporal accuracy, instead, focused on the Dorgola Valley (Province of Reggio Emilia). The assessment of spatial accuracy involved a comparison between remotely sensed and field survey data, as well as an innovative fuzzylike analysis of a multi‐temporal landslide inventory map. Conversely, long‐ and short‐term landslide temporal persistence was appraised over a period of 60 years with the aid of 18 remotely sensed image sets. These results were eventually compared with the current Territorial Plan for Provincial Coordination (PTCP) of the Province of Reggio Emilia. The outcome of this work suggested that geomorphologically detected and mapped landslides are a significant approximation of a more complex reality. In order to convey to the end‐users this intrinsic uncertainty, a new form of cartographic representation is needed. In this sense, a fuzzy raster landslide map may be an option. With regard to land‐use planning, landslide inventory maps, if appropriately updated, confirmed to be essential decision‐support tools. This research, however, proved that their spatial and temporal uncertainty discourages any direct use as zoning maps, especially when zoning itself is associated to statutory or advisory regulations.

Landslide hazard and risk are growing as a consequence of climate change and demographic pressure. Land‐use planning represents a powerful tool to manage this socio‐economic problem and build sustainable and landslide resilient communities. Landslide inventory maps are a cornerstone of land‐use planning and, consequently, their quality assessment represents a burning issue. This work aimed to define the quality parameters of a landslide inventory and assess its spatial and temporal accuracy with regard to its possible applications to land‐use planning. In this sense, I proceeded according to a two‐steps approach. An overall assessment of the accuracy of data geographic positioning was performed on four case study sites located in the Italian Northern Apennines. The quantification of the overall spatial and temporal accuracy, instead, focused on the Dorgola Valley (Province of Reggio Emilia). The assessment of spatial accuracy involved a comparison between remotely sensed and field survey data, as well as an innovative fuzzylike analysis of a multi‐temporal landslide inventory map. Conversely, long‐ and short‐term landslide temporal persistence was appraised over a period of 60 years with the aid of 18 remotely sensed image sets. These results were eventually compared with the current Territorial Plan for Provincial Coordination (PTCP) of the Province of Reggio Emilia. The outcome of this work suggested that geomorphologically detected and mapped landslides are a significant approximation of a more complex reality. In order to convey to the end‐users this intrinsic uncertainty, a new form of cartographic representation is needed. In this sense, a fuzzy raster landslide map may be an option. With regard to land‐use planning, landslide inventory maps, if appropriately updated, confirmed to be essential decision‐support tools. This research, however, proved that their spatial and temporal uncertainty discourages any direct use as zoning maps, especially when zoning itself is associated to statutory or advisory regulations.

The rock slope failure object of this study occurred on the 12th of March, 2005, within the Scascoli Gorges in the Savena Valley, 25 km south of Bologna, in the Northern Apennines, Italy. The failure involved a volume of rock of nearly 30000 m3 that detached from an 80 m high cliff and fell on the river bed and onto the adjacent road, denoted as “Strada Provinciale – Fondovalle Savena”, damming the first and destroying the latter. The conformation of the cliff, known as “Mammellone 1”, was rather convex, overhanging and undercut at the base where in contact with the river bed. The event is the last of a series of mass movements which occurred in a 15-year span in the area. With integration of past analyses and surveys, possible causes and mechanism of failure have been investigated by means of two and three-dimensional kinematic analysis (using the software DIPS and SWEDGE by Rocscience, 2016), photogrammetry and terrestrial laser scanning comparison (Cloud Compare, Daniel Girardeau-Montaut, 2016; Autocad, Autodesk, 2016) and two-dimensional finite element numerical modelling (RS2, Rocscience, 2016). The use of a finite element method to model a predominantly blocky structure has shown to be effective and to produce good results if data integration, boundary conditions and geometry of the site are well correlated between each other to best fit the resulting scenario. The design of the numerical model considered the relative position of crown and scarp to the discontinuity families and to the geometry of the cross section, to better costrain the failure surface. Furthermore, the process of formation of the valley was taken into account in order to consider also stress-strain conditions prior to the road construction and river erosion. This was carried out by multi-staging the modelling process considering the natural erosion and the advancement of the landslide on the hydrogeological left side of the Savena steam before the last rockfall event.

Abandoned croplands can be considered a new category of “scattered elements” of mountain landscapes. To gain deeper understanding of the conservation status (sensu EEC Directive 92/43) of abandoned cropland in the northern Apennines, we coupled the concepts of the social behavior type (SBT) and the functional assessment of plant communities. SBTs refer to behaviour and ecological attributes of species at a given observation level and allow the understanding of the plant community conservation status, while the functional approach may help in predicting changes of species composition along disturbance and stress gradients. We found that topographic and soil conditions drive the species assemblage in pastures after crop abandonment, but long-term abandonment does not lead per se to the recovery of the semi-natural grassland communities deemed worthy of conservation in the EEC Directive. It was mainly due to the lack of appropriate disturbance regimes that allows the spread of dominant tall herbs, which, in turn, reduces the site suitability for subordinate plants. Moreover, their spread fosters the presence of elements such as ruderals and fringe species. We conclude that, these abandoned croplands have a good potential to develop into Habitat of EU Directive but without appropriate management plans they will remain of low representativeness.

Abandoned croplands can be considered a new category of “scattered elements” of mountain landscapes. To gain deeper understanding of the conservation status (sensu EEC Directive 92/43) of abandoned cropland in the northern Apennines, we coupled the concepts of the social behavior type (SBT) and the functional assessment of plant communities. SBTs refer to behaviour and ecological attributes of species at a given observation level and allow the understanding of the plant community conservation status, while the functional approach may help in predicting changes of species composition along disturbance and stress gradients. We found that topographic and soil conditions drive the species assemblage in pastures after crop abandonment, but long-term abandonment does not lead per se to the recovery of the semi-natural grassland communities deemed worthy of conservation in the EEC Directive. It was mainly due to the lack of appropriate disturbance regimes that allows the spread of dominant tall herbs, which, in turn, reduces the site suitability for subordinate plants. Moreover, their spread fosters the presence of elements such as ruderals and fringe species. We conclude that, these abandoned croplands have a good potential to develop into Habitat of EU Directive but without appropriate management plans they will remain of low representativeness.

The Variscan basement of Northern Apennines (Northern Italy) is a polymetamorphic portion of continental crust. This thesis investigated the metamorphic history of this basement occurring in the Cerreto Pass, in the Pontremoli well, and in the Pisani Mountains. The study comprised fieldwork, petrography and microstructural analysis, determination of the bulk rock and mineral composition, thermodynamic modelling, conventional geothermobarometry, monazite chemical dating and Ar/Ar dating of muscovite. The reconstructed metamorphic evolution of the selected samples allowed to define a long-lasting metamorphic history straddling the Variscan and Alpine orogenesis. Some general petrological issues generally found in low- to medium-grade metapelites were also tackled: (i) With middle-grade micaschist it is possible to reconstruct a complete P-T-D path by combining microstructural analysis and thermodynamic modelling. Prekinematic white mica may preserve Mg-rich cores related to the pre-peak stage. Mn-poor garnet rim records the peak metamorphism. Na-rich mylonitic white mica, the XFe of chlorite and the late paragenesis may constrain the retrograde stage. (ii) Metapelites may contain coronitic microstructures of apatite + Th-silicate, allanite and epidote around unstable monazite grains. Chemistry and microstructure of Th-rich monazite relics surrounded by this coronitic microstructure may suggest that monazite mineral was inherited and underwent partial dissolution and fluid-aided replacement by REE-accessory minerals at 500-600°C and 5-7 kbar. (iii) Fish-shaped white mica is not always a (prekinematic) mica-fish. Observed at high-magnification BSE images it may consist of several white mica formed during a mylonitic stage. Hence, the asymmetric foliation boudin is a suitable microstructure to obtain geochronological information about the shearing stage. (iv) Thermodynamic modelling of a hematite-rich metasedimentary rock fails to reproduce the observed mineral compositions when the bulk Fe2O3 is neglected or determined through titration. The mismatch between observed and computed mineral compositions and assemblage is resolved by tuning the effective ferric iron content by P-XFe2O3 diagrams.

The Variscan basement of Northern Apennines (Northern Italy) is a polymetamorphic portion of continental crust. This thesis investigated the metamorphic history of this basement occurring in the Cerreto Pass, in the Pontremoli well, and in the Pisani Mountains. The study comprised fieldwork, petrography and microstructural analysis, determination of the bulk rock and mineral composition, thermodynamic modelling, conventional geothermobarometry, monazite chemical dating and Ar/Ar dating of muscovite. The reconstructed metamorphic evolution of the selected samples allowed to define a long-lasting metamorphic history straddling the Variscan and Alpine orogenesis. Some general petrological issues generally found in low- to medium-grade metapelites were also tackled: (i) With middle-grade micaschist it is possible to reconstruct a complete P-T-D path by combining microstructural analysis and thermodynamic modelling. Prekinematic white mica may preserve Mg-rich cores related to the pre-peak stage. Mn-poor garnet rim records the peak metamorphism. Na-rich mylonitic white mica, the XFe of chlorite and the late paragenesis may constrain the retrograde stage. (ii) Metapelites may contain coronitic microstructures of apatite + Th-silicate, allanite and epidote around unstable monazite grains. Chemistry and microstructure of Th-rich monazite relics surrounded by this coronitic microstructure may suggest that monazite mineral was inherited and underwent partial dissolution and fluid-aided replacement by REE-accessory minerals at 500-600°C and 5-7 kbar. (iii) Fish-shaped white mica is not always a (prekinematic) mica-fish. Observed at high-magnification BSE images it may consist of several white mica formed during a mylonitic stage. Hence, the asymmetric foliation boudin is a suitable microstructure to obtain geochronological information about the shearing stage. (iv) Thermodynamic modelling of a hematite-rich metasedimentary rock fails to reproduce the observed mineral compositions when the bulk Fe2O3 is neglected or determined through titration. The mismatch between observed and computed mineral compositions and assemblage is resolved by tuning the effective ferric iron content by P-XFe2O3 diagrams.

The aim of this research is to conduct an investigation on the soils, paleosols and landforms of the area of Mt Cusna ridge (Northern Apennines - Italy) in order to define the relationship between geomorphic evolution and soil development, to characterise the main pedogenetic processes and factors acting on soils in past and present times, and to provide new information to understanding the Holocene climatic variations in the area. For this purpose, several sets of field, laboratory and microscopic analyses were carried out. A comprehensive survey of the study area allowed the production of a geomorphological map (scale 1:10000, attached to this thesis) expanding and revising the existing cartography (Panizza et al., 1982). At the same time, also the soils were surveyed and described, in order to provide a detailed characterisation of the soil types of the area. Selected soil profiles were sampled and underwent a wide set of laboratory analyses, including measurements of pH, exchangeable bases and cation exchange capacity (CEC), organic carbon content, total nitrogen and exchangeable phosphorus; along these iron oxides were investigated with the measurement of total iron and its extractable forms; grain size analyses and x-ray diffractions on the clay fraction were also carried out; finally, micromorphology of soil thin sections and SEM observations and analyses were also carried out on a subset of significant horizons. Geomorphological survey results allowed to compare the active and inactive processes. Glacial and periglacial processes, though mainly inactive since the beginning of the Holocene, still give an important forcing on the present landscape through their deposits, produced during the Last Glacial period. During the Holocene, different phases of stability and instability could be detected from the activation an reactivation of slope dynamics as the result of both climate fluctuations and structural constraints. The result is a very diversified landscape in which erosion and deposition alternate in space and time. The present day conditions are characterised by a prevalence of washout and erosion activity, mainly on lithologies more susceptible to surface processes. Soils were attributed to different landscape units, highlighting differences in processes and development between them. Degree of pedogenesis, in fact, varies from weakly developed soils on the highest and steeper areas to deep and more weathered profiles at lower elevations and/or on flatter surfaces. Among the latter, the presence of a paleosurface, characterised by the presence of paleosol units truncated and buried by colluvial deposits, has been detected in the stable areas above 1650 m a.s.l.. Laboratory geopedological analyses showed how soil in the area are characterised by being mainly silty-clayey, with low values of pH and organic C which tends to concentrate at the surface and in many cases also in the uppermost horizon of buried soil units. Iron oxides are usually present in its crystalline form, with some exceptions in peculiar soils. The crystalline/total iron ratio (weathering index) is generally low, higher inside paleosurface buried units. Clay fraction mineralogy shows the presence of quartz and chlorite inherited from parent material; neoformed clay minerals consist in illite and mixed layer clays. Micromorphological analysis mainly involved paleosurface horizons. Colluvial units show the presence of variable quantities of pedorelicts (Brewer, 1967) in their groundmass, as well as features pointing to multiple depositional events. The buried unit shows different phases of clay illuviation relatable to environmental changes. In flat areas a 2Ab horizon is found between the two units, showing accumulation of excrements and organic material; features of frost action are also present. Particular conditions are related to higher elevations as well as areas with steeper slopes. Data obtained from field and analytical approaches allowed to outline the main pedogenetic processes acting in the area. Pedogenesis started since the glacial retreat: clay mineralogy and iron oxide content are compatible with a soil formation taking place during the Holocene. The main active process in the area is Brunification (Duchaufour, 1983), which drive the development of Regosols and Cambisols (FAO, 2014); these soils are better developed at lower elevations on flat areas and stable deposits, whereas soils on steeper slopes and higher elevations show evidences of a weaker pedogenesis. Luvisols (FAO, 2014) were also formed in the past and are mainly preserved as paleosols of the buried units related to the paleosurface; moreover the clayey pedofeatures of these paleosols allowed the identification of three different clay illuviation phases, preceding the Subboreal climatic recrudescence 14C dated (Compostella et al., 2012; Giraudi, 2014). During the Late Holocene in the area appears Podzolisation (Duchaufour, 1983) as a secondary process, as testified by the presence of cryptopodzolisation features in soil profiles from different areas. Traces of this process could be also found inside the 2Ab horizon, marking the top of the buried unit in some soil profiles surveyed on the paleosurface; this horizon can be characterised as an accumulation of insect excrements and organic material developed in cold conditions. A change in vegetation cover detected by anthracological assemblages (Compostella et al., 2012) seems to confirm this hypothesis. 14C dating (Compostella et al., 2012) and frost features inside the 2Ab horizon date its burial to the Little Ice Age (LIA), which marks a phase of general erosion causing colluvial deposition also in flatter areas, which probably happened in multiple events through time. The colluvial layers show apparent pedogenesis caused by the presence of pre-weathered soil material and signs of homogenisation probably related to cryoturbation processes. Finally, the presence of frost and solifluction features inside these recent soils point to the characterisation of the LIA as a drier period in which winter precipitation were less abundant and snow cover thinner. This study outlined the existence of complex interactions between pedogenic, geomorphic and environmental processes throughout the Holocene. The influence of these aspects on soil features could be detected and used to describe and interpret the present landscape in the light of its modifications through time.

This study focuses on the detailed investigation of the brittle/plastic transition in quartz-feldspathic rocks at upper-middle crustal conditions and aims to better understand the role of fluids and temperature during deformation. The Calamita Unit (Elba Island, Italy) is a high metamorphic grade unit (T ~ 650 °C) that has been intruded by a monzogranite body at shallow crustal level (P < 0.2 GPa) and coevally deformed during regional shortening for a limited time span (< 1 Ma). These conditions outline the Calamita Unit as an ideal case study to investigate the brittle/plastic transition at approximately constant pressure (i.e. depth) during temperature decrease, reproducing upper-middle crustal conditions. The Calamita Schists are a metapsammitic complex exposed in the lower part of the Calamita Unit. Pseudosection modelling and Ti-in-biotite thermometry constrain the peak metamorphic assemblage, marked by andalusite + cordierite + biotite + K-feldspar, at upper amphibolite facies conditions (T ~ 600 – 700 °C; P ~ 0.2 GPa), with microstructures suggesting partial melting. The retrograde path is constrained by chlorite geothermometry in the 300 – 500 °C temperature range. Detailed field mapping and structural analysis have revealed at map-scale a pattern of heterogeneous deformation characterized by west-dipping high-strain domains localizing eastward-directed deformation interleaved with relatively low-strain domains. In high-strain domains, mylonitic fabrics are, in turn, overprinted in the brittle regime by non-Andersonian subhorizontal faults associated with Riedel shears networks, formed subparallel to C’ shear bands. Microstructural analysis highlights that temperature decrease and fluid influx controlled the mechanical evolution of the investigated rocks, which are marked by the transition from a high-metamorphic grade foliation to shear bands and mylonites with widespread S-C and S-C’ fabrics, characterized by retrograde, synkinematic white mica and chlorite. Quartz microfabric displays an evolution from fast grain boundary migration, developed close to peak metamorphic conditions, to subgrain rotation and bulging recrystallization, tracking decreasing temperature during deformation. During decreasing temperature, deformation localized in mylonitic quartz ribbons at amphibolite facies conditions (450 °C < T < 600 °C), where recrystallization was accommodated by dislocation creep of quartz under dominant prism slip, causing the development of strong Y-maximum crystallographic preferred orientations (CPO). Secondary rhomb and acute rhomb slip assisted the recrystallization of grains unfavorably oriented for prism slip, with the activation of slip systems whose misorientation axis lies close to the vorticity axis. At greenschist facies conditions (300 °C < T < 450 °C), deformation localized in phyllonitic domains, producing phase mixing of phyllosilicates and tiny quartz grains. Relic, large quartz grains hardened and fractured along synthetic and conjugate shear bands. The propagation of shear bands occurred under fluid-rich conditions and was controlled by cyclic fracturing and precipitation of new quartz and phyllosilicate grains, deposited by circulating fluids. Precipitated new quartz grains developed a CPO parallel to shear bands controlled by the opening of dilatant sites. The nucleation of fine-grained quartz and ‘soft’ phyllosilicates enhanced strain softening and assisted strain partitioning into localized C’ shear bands at the brittle/plastic transition. In the brittle regime (T ~ 300 °C), deformation localized on previously formed C’ shear bands, favorably oriented for reactivation, that acted as ductile precursors for misoriented non-Andersonian faults. Brittle deformation in fault zones was controlled by the cyclical interaction between fracturing, taking advantage of weak crystallographic planes in quartz such as the rhombs, and fluid infiltration, assisting the precipitation of new quartz and phyllosilicate grains, lacking a clear preferred orientation. The data presented in this thesis highlight the role played by fluids during deformation of quartz-feldspathic rocks at the brittle/plastic transition, that efficiently control (1) strain softening of ‘stiff’ domains and (2) strain localization into shear bands that have the potential to act as precursors for non-Andersonian fault zones. The proposed model predicts the development of brittle structures discordantly overprinting ductile fabrics developed in the same kinematic regime, which bears implications for the tectonic evolution of rock volumes (i.e. tectonic units and/or metamorphic complexes) exhumed though the brittle/plastic transition.

Title: Anisotropy of the upper mantle under the Northern Apennines based on data from the international experiment RETREAT (Italy) Author: Helena Munzarová Department: Department of Geophysics Supervisor of the master thesis: RNDr. František Gallovič, Ph.D. Department of Geophysics Consultant of the master thesis: RNDr. Jaroslava Plomerová, DrSc. Institute of Geophysics, Czech Academy of Sciences Abstract: In this master thesis, we process data recorded during the passive seismic experiment RETREAT (2003-2006) in the Northern Apennines with the aim to explore the upper mantle structure in the region. Active orogeny in the Northern Apennines relates to the collision of the Tyrrhenian and Adriatic (subducting westward) plates and is accompanied by an eastward retreat of the trench. Directional dependences of P-wave travel-time deviations together with variations of the fast split polarization azimuths of teleseismic SKS waves are derived from data recorded during experiment RETREAT. Both the fossil anisotropic structure in the mantle lithosphere and the anisotropy due to the present-day flow in the sub-lithospheric mantle are sources of the observed velocity-anisotropy patterns. Thick continental Adriatic plate can be divided into at least two sub-regions with their own fossil fabrics. We have also tried to...