The area studied in this thesis work is located in the surroundings of Lumignano, in the municipality of Longare (Vi). In this locality, in the late Oligocene-Miocene, a system of faults was established, related to Alpine tectonic events. The purpose of this study was to define the various tectonic phases that occurred in the area surrounding Lumignano, and their temporal relationship with respect to the opening of the karst cavities. The stratigraphy in the Lumignano area consists of Eocene marly limestones and Oligocene limestones, the latter belonging to the Castelgomberto Formation. Oligocene limestones locally form subvertical walls, consisting of boundstones and corals. These then underwent karst phenomena, with the consequent formation of covoli, caves, with a horizontal development, characterized by large rooms with a rounded plan and communicating with the outside directly or through short passages. In order to develop this project, two paths were taken: A first phase was the acquisition of detailed tectonic data, through direct measurement in the countryside, with classical methods; and in a second phase aerial photogrammetry was used, through the use of a drone, for a subsequent generation of a georeferenced 3D model. From the photogrammetric models data have been acquired on the tectonic structures present in the Castelgomberto Formation. A first phase was that of acquiring detailed tectonic data, by direct measurement in the countryside, with classical methods. The different tectonic phases found in the area have been described both in geometric and kinematic terms. There are two main tectonic phases found in the study area. A first phase, with normal kinematics, in which it has the NE-SW axis of maximum extension, which has generated two fault systems, a main one on NW-SE directions and a secondary one on NE-SW directions. The second phase, on the other hand, is established on pre-existing fault planes with reactivation in left transience, this is found only on NW-SE trending fault planes. As evidence of this, kinematic indicators referring to the first phase of normal faulting can be found, superimposed by kinematic indicators, roughly orthogonal, referring to the second tectonic phase with left strike-slip component. Finally, it was found that, as a consequence of both two tectonic phases imposed, some of the karst structures, called covoli, underwent a dislocation, clearly modifying their initial morphology.
L’area in studio si trova nei dintorni di Lumignano, in comune di Longare (Vi). In questa località, nel tardo Oligocene-Miocene, si è instaurato un sistema di faglie ad alto angolo, relazionabili ad eventi tettonici alpini. Lo scopo di questo studio è stato quello definire le varie fasi tettoniche avvenute nell’area circostante Lumignano, ed il loro rapporto temporale rispetto all’apertura delle cavità carsiche. La stratigrafia nell’area di Lumignano è costituita da calcari marnosi eocenici e da calcari oligocenici, questi ultimi appartenenti alla Formazione di Castelgomberto. I calcari oligocenici formano localmente pareti subverticali, costituite da boundstone a coralli. Questi hanno poi subito carsismo, con la conseguente formazione di covoli, cioè grotte a sviluppo orizzontale e caratterizzate da ampie sale a pianta rotondeggiante e comunicanti con l’esterno direttamente o tramite brevi passaggi. La successione eocenico-oligocenica è infine tagliata da filoni e camini vulcanici, di età presumibilmente oligocenica superiore. Per poter sviluppare questo progetto, si sono intraprese due strade: in prima fase si è utilizzata la fotogrammetria aerea, mediante l’utilizzo di un drone, per una successiva generazione di un modello 3D georeferenziato. Dai modelli fotogrammetrici si sono acquisiti dati, sulle strutture tettoniche presenti nella Formazione di Castelgomberto. Una seconda fase invece, è stata quella dell’acquisizione di dati tettonici di dettaglio, tramite misurazione diretta in campagna, con metodi classici. Le principali fasi tettoniche riscontrate nell’area studio sono due. Una prima fase, con cinematica normale. Mentre una seconda fase, si instaura su piani di faglia preesistenti riattivati in trascorrenza sinistra. A testimonianza di questo si possono rinvenire indicatori cinematici, riferiti alla prima fase di fagliazione normale, sovrapposti da indicatori cinematici, all’incirca ortogonali, riferibili alla seconda fase tettonica con componente trascorrente sinistra. Le faglie con cinematica trascorrente sinistra, presentano l’asse di stress maggiore (Sigma1) orientato circa WSW-ENE, mentre l’asse di stress minore (Sigma3) ha direzione circa NNW-SSE. Sono stati individuati rapporti di intersezione tra le faglie di diverse fasi tettoniche, i covoli e i filoni magmatici.
Studio stratigrafico e strutturale della relazione tra tettonica e grotte nei calcari oligocenici di Lumignano (Vicenza).
BREGOLIN, MARCO
2022/2023
Abstract
The area studied in this thesis work is located in the surroundings of Lumignano, in the municipality of Longare (Vi). In this locality, in the late Oligocene-Miocene, a system of faults was established, related to Alpine tectonic events. The purpose of this study was to define the various tectonic phases that occurred in the area surrounding Lumignano, and their temporal relationship with respect to the opening of the karst cavities. The stratigraphy in the Lumignano area consists of Eocene marly limestones and Oligocene limestones, the latter belonging to the Castelgomberto Formation. Oligocene limestones locally form subvertical walls, consisting of boundstones and corals. These then underwent karst phenomena, with the consequent formation of covoli, caves, with a horizontal development, characterized by large rooms with a rounded plan and communicating with the outside directly or through short passages. In order to develop this project, two paths were taken: A first phase was the acquisition of detailed tectonic data, through direct measurement in the countryside, with classical methods; and in a second phase aerial photogrammetry was used, through the use of a drone, for a subsequent generation of a georeferenced 3D model. From the photogrammetric models data have been acquired on the tectonic structures present in the Castelgomberto Formation. A first phase was that of acquiring detailed tectonic data, by direct measurement in the countryside, with classical methods. The different tectonic phases found in the area have been described both in geometric and kinematic terms. There are two main tectonic phases found in the study area. A first phase, with normal kinematics, in which it has the NE-SW axis of maximum extension, which has generated two fault systems, a main one on NW-SE directions and a secondary one on NE-SW directions. The second phase, on the other hand, is established on pre-existing fault planes with reactivation in left transience, this is found only on NW-SE trending fault planes. As evidence of this, kinematic indicators referring to the first phase of normal faulting can be found, superimposed by kinematic indicators, roughly orthogonal, referring to the second tectonic phase with left strike-slip component. Finally, it was found that, as a consequence of both two tectonic phases imposed, some of the karst structures, called covoli, underwent a dislocation, clearly modifying their initial morphology.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/43246