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Highly fractured Mesozoic carbonate rocks are the main reservoir of many geothermal resources in northern Croatia, being of environmental, cultural, and economic value for the local and regional communities. The Daruvar thermal springs (temperatures < 50°C) represent the outflow area of an intermediate scale, tectonically controlled, hydrothermal system hosted in Triassic carbonate rocks. Several investigations have been conducted in the Daruvar area detailing the architecture of regional and local fracture networks and quantifying the hydrogeological parameters of the thermal aquifer. In this work, an integrated approach based on structural and hydrogeological investigations was employed to model the network of fractures in the reservoir and quantify its impact on the hydraulic properties. Structural investigations were conducted in the Batinjska Rijeka quarry, considered as an outcrop analogue of the thermal aquifer, employing both a classical field approach and the virtual quantitative analysis of a 3D digital outcrop model. Structural analysis of the digital outcrop model allowed identification of two sub-vertical systems of discontinuities, dipping to the NW and the WSW respectively, in accordance with the data collected through direct field measurements. The main geometric features of the discontinuity network and their statistical distributions were employed to construct discrete fracture network models at both the outcrop scale (approximately 100 m) and the aquifer scale in Daruvar (approximately 700 m). Calibration of the input parameters allowed modelling of porosity and permeability values that reproduce the field values assessed through pumping tests, well tests, and well logging. This work highlights the importance of integrating geological and hydrogeological investigations to obtain a more reliable reconstruction and quantification of the processes driving the fluid flow in fractured aquifers and affecting the spatial distribution of their hydrauli

Questa tesi tratta della creazione di modelli 3D strutturali su larga scala (x1) e su scala locale (x2) di regioni delle Alpi Pennine, per cui introduco workflow di modellazione 3D che combinano dati strutturali di terreno (sia originali che già pubblicati) con algoritmi di modellazione implicita. L'approccio di modellazione implicito rappresenta l'architettura tettonica costruendo un’analogia tra la distanza relativa tra strutture geologiche e un campo scalare volumetrico. In questo campo, le strutture geologiche sono rappresentate da superfici di equipotenziali, e la loro geometria è vincolata da osservazioni geologiche di terreno che influenzano sia valore che l'orientamento del campo scalare. In particolare, in questa tesi utilizzo l'algoritmo Discrete Smooth Interpolator. Le aree di studio sono situate nelle Alpi nord-occidentali, tra il Monte Bianco e il Monte Rosa, e non sono mai state oggetto di uno studio di modellazione 3D di questa portata. Nella regione sono esposti il dominio Austroalpino, il Piemontese, il Pennidico e il sistema Elvetico-Ultraelvetico. Questa sequenza tettonica è rappresentata nel primo modello 3D presentato in questa tesi, che si estende per circa 1.500 km2 lungo il confine tra Italia e Svizzera. Il workflow di modellazione per questo modello prevede la creazione di interpretazioni strutturali in sezioni verticali, necessarie a ottenere un risultato che rispetti principi di realismo geologico. Il risultato è un modello deterministico che cattura la conoscenza dell'architettura tettonica a scala regionale, rappresentando strutture quali zone di taglio, pieghe ripiegate, isoclinali e/o coricate, e il reticolo di faglie. Successivamente, la tesi si focalizza su due regioni di dimensioni inferiori (estensioni inferiori ai 30 km2), quali l'area del Lago di Cignana e la dorsale Tournalin-Roisetta, locate all'interno dei confini del modello regionale. Con l'obiettivo di minimizzare l’input soggettivo interpretativo, i workflow di modella, The overarching theme presented this thesis is the generation of large (x1) and local-scale (x2) 3D structural models of regions of the Pennine Alps, for which I introduce modelling workflows that combine high-resolution new and legacy structural datasets derived from fieldwork with implicit modelling algorithms. The implicit approach builds the tectonic architecture as an analogy between the relative distance among geological structures and a volumetric scalar field, within which geological structures are represented as isovalue surfaces. In particular, in this thesis I employ the Discrete Smooth Interpolator algorithm. The study areas, situated in the northwestern Alps between Mont Blanc and Monte Rosa, lacked prior comprehensive three-dimensional representations. This region exhibits the Austroalpine-Penninic collisional wedge and the Helvetic-Ultrahelvetic sequence of thrust sheets. This tectonic sequence is represented in the first, regional-scale 3D model presented in this thesis, spanning approximately 1,500 km2 along the Italian-Swiss boundary. The modelling workflow for the creation of this model incorporates structural interpretations on vertical cross-sections to propagate geological knowledge to the subsurface, ensuring the geological realism of the final outcome, resulting in a deterministic model that provides a comprehensive summary of the tectonic architecture and captures the state of the knowledge about the region. Geological structures represented by the model include hierarchical shear zones, isoclinal and/or recumbent folds, and networks of faults. Successively, I redirect my attention to two more localised regions (extensions less than 30km2) encompassed within the boundaries of the regional model, the Lago di Cignana area and the Tournalin-Roisetta ridge. With the objective of reducing subjectivity and uncertainty of the final outcomes, I employ techniques that rely on the abundance of the structural database and leverage constraints provided

Durante gli eventi eruttivi, il magma si propaga verso la superficie attraverso dicchi verticali. Tuttavia, nella maggior parte dei casi, questi dicchi si arrestano nella crosta, senza provocare un'eruzione. La messa in posto di dicchi nella parte più superficiale della crosta provoca una concentrazione di sforzi di trazione e taglio nella roccia incassante, che possono portare a deformazioni fragili sulla superficie topografica, con la formazione di fratture estensionali e faglie normali, spesso creando un graben. Negli ultimi decenni sono stati utilizzati modelli analitici, analoghi e numerici per analizzare la relazione tra l’intrusione di magma e la deformazione superficiale indotta dai dicchi; la maggior parte di questi modelli, però, utilizza uno semispazio elastico, omogeneo e isotropo, senza tenere conto delle eterogeneità della crosta. Per superare questa limitazione ed evitare errori nella ricostruzione della geometria del dicco, quindi, è necessario prendere in considerazione dati realistici raccolti sul campo. Per questo motivo, in questo progetto, ho integrato dati strutturali realistici con la modellazione numerica. Le aree di studio sono situate sull'Etna (Italia), lungo le fessure eruttive del 1928 e del 1971, e nel sud-ovest dell'Islanda, lungo la fessura eruttiva “Younger Stampar”. Questi casi di studio sono stati tutti interessati dalla messa in posto di dicchi a basse profondità. Sull'Etna, ciò ha portato ad una deformazione fragile della superficie, che oggi è ancora visibile in pianta e, per il caso di studio del 1971, anche in sezione. Lo scopo principale è quello di indagare i parametri che i) promuovono o inibiscono la deformazione fragile indotta dai dicchi in superficie, ii) controllano la geometria delle faglie del graben indotte dai dicchi e iii) favoriscono l'arresto dei dicchi a basse profondità. Per raccogliere nuovi dati strutturali, ho integrato il classico lavoro sul campo con analisi su modelli 2D e 3D ad alta risoluzione, During eruptive events, magma propagates vertically towards the surface through magma-filled fractures, referred to as dikes. However, in most cases dikes arrest in the crust, not leading to an eruption. In shallow settings, dike emplacement causes a concentration of tensile and shear stresses in the host rock, which can lead to brittle deformation at the topographic surface, with the formation of tension fractures and normal faults, often creating a graben. In the last decades, analytical, analogue and numerical models have been designed to analyze the relation between magma emplacement and dike-induced surface deformation, but mostly with an elastic half-space, homogeneous and isotropic, without taking into account the layering of the crust. Realistic field data should be considered to overcome this limitation, to avoid errors in the reconstruction of dike geometry. For this reason, in this project, I integrated realistic structural data with numerical modeling. Study areas are located on Mt. Etna (Italy), along the 1928 and 1971 eruptive fissures, and in SW Iceland, along the Younger Stampar eruptive fissure. These case studies were all affected by shallow dike emplacement. On Mt. Etna, this led to brittle surface deformation, which is nowadays still visible in plan view and, for the 1971 case study, also in section view. The main aim is to investigate the parameters that i) promote or inhibit dike-induced brittle deformation at the surface, ii) control the geometry of dike-induced graben faults, and iii) favor dike arrest at shallow depths. To collect new structural data, I integrated classical fieldwork with remote sensing analyses, thanks to high-resolution 2D and 3D models derived from drone-collected images and historical aerial photographs through Structure from Motion (SfM) techniques. All these data were then used as inputs for Finite Element Method (FEM) numerical modeling using the software COMSOL Multiphysics®, running sensitivity analyses to understan

Active fold-and-thrust belts create new landslide-prone slopes during tectonic deformation propagation. However, studies on landslide distribution in newly formed fold-and-thrust belts are limited. In this study, we present a new inventory of landslides in the Kura fold-and-thrust belt, a tectonically active, but relatively low-altitude southern margin of the Greater Caucasus. The area has been tectonically framed in the last ~2–3 Ma and is represented by folds and thrusts deforming Miocene to Quaternary sediments. Through satellite imagery analysis, we mapped nearly 1600 landslides, with a quarter currently active. While landslides cover <1 % of the area, they tend to cluster at higher elevations and in regions with relatively high local relief. Landslides predominantly occur in tectonically uplifted areas, affecting the highest and steepest parts of growing anticlines and the steep slopes of incising valleys intersecting active thrust faults. Based on observed landslide distribution in folds at different stages of development, we propose a conceptual model for the temporal evolution of landslide patterns in weak sediment-based fold-and-thrust belts: 1) In the initial stages, slow-moving slope deformations affect incipient thrust fronts. With the flanks of the growing anticline lacking sufficient steepness, landslides tend to concentrate in deep valleys intersecting the uplifting hanging walls. 2) With ongoing thrust uplift, growing and steepening anticlines become more prone to planar sliding when dip slopes exceed friction angle, and valley development creates additional dip slopes, resulting in widespread landslides. 3) In the final stage, erosional decay reduces topographic relief, leading to badland formation with gully erosion and decreased landslide occurrence.

Late Cretaceous metamorphic events are known in Crete and the Cyclades from klippen above the External Hellenides. This work extends their occurrence to the North Aegean area within the tectonic units of the Internal Hellenides. New 40Ar/39Ar white mica ages from garnet-bearing micaschists of the Upper Metamorphic Unit of Skyros Island, cropping out in the Skyrian Olympus Mountain, document a Late Cretaceous tectono-metamorphic evolution. Several mica generations have been distinguished using electron probe microanalyses and were dated using the 40Ar/39Ar method: a relict mica older than 96 Ma, followed by a foliation-forming mica of about 88–84 Ma and alteration phases ≤ 68 Ma were recognized. This Cretaceous tectono-metamorphic evolution falls between the closure of the internal Axios/Vardar oceanic basin in the Late Jurassic–Early Cretaceous, and the closure of the external Pindos–Cyclades oceanic basin in the Early Cenozoic. The position of the Upper Metamorphic Unit of Skyros was probably within the evolving Hellenic volcanic/magmatic arc during the continuous subduction of the African plate beneath the European plate. The present tectonic position of the units bearing the Late Cretaceous metamorphic event is the result of the Cenozoic tectonic emplacement onto the more external units across the Hellenides from the Pelagonian to the Pindos–Cyclades domain.

Geodynamic models implying subduction of continental crust either consider this process happening during collision, when the continental margin of the lower plate attempts subduction, or in pre-collisional stages, when tectonic erosion of the upper plate or subduction of continental extensional allochthons drag continental crust in the subduction channel. In the Zagros orogen (W Iran), high-pressure rocks are known only from the Sanandaj-Sirjan Zone, NE of the Main Zagros Thrust. Here, eclogites of the North Shahrekord Metamorphic Complex suggest subduction of continental crust slices derived from the upper plate (Central Iran) during the onset of the Neo-Tethys subduction along the southern margin of Iran. Eclogites record a clockwise pressure-temperature-time path, with pre-eclogitic epidote-amphibolites-facies phase assemblages preserved in garnet cores, a high-pressure stage, and a subsequent retrogression at amphibolite-facies conditions. By means of forward thermodynamic modelling and 40Ar/39Ar geochronology, the peak metamorphism has been constrained at 1.9-2.1 GPa and 550-600 °C, in the 191-194 Ma time span. The following retrogression during exhumation lasted at least until 144 Ma. Our data suggest that the onset of the Neo-Tethys subduction traces back prior to 190 Ma, involving together with the Neo-Tethys oceanic lithosphere also slices of the upper plate continental crust scraped off by means of tectonic erosion processes.