1,721,145 research outputs found
Carta Geotettonica della Valle d'Aosta
No full textCarta geologico-strutturale della Regione Autonoma Valle d'Aosta, stampata alla Scala 1:150.000. Si tratta di un estratto del Sistema Informativo Territoriale (GIS) realizzato per mantenere aggiornate e fruibili le informazioni riguardanti la geotettonica di questo importante settore dell'Arco Alpino. II lavoro è stato realizzato a partire dalla Carte geologique de la Vallée d'Aoste alla Scala 1:100.O00 di Giulio Elter (1987), aggiornata in base allo Structural Model of Italy (Bigi et al., 1990) e a successivi contributi di carattere regionale o locale; le maggiori innovazioni riguardano il settore centro-orientale della carta. La Valle d'Aosta espone una significativa sezione della catena collisionale delle Alpi nord-occidentali, dalle unità elvetiche e ultraelvetiche del Monte Bianco-M. Chetif, accrete nell'Oligocene-Neogene, al complesso di subduzione fossile austroalpino-pennidico, formatosi tra l'Eocene e il tardo Cretacico. II complesso di subduzione costituito dalle unità pennidiche esterne (Zona Sion-Courmayeur), mediane (Gran San Bernardo) ed interne (Monte Rosa, Gran Paradiso), derivate dal margine continentale passivo europeo, dalle unità ofiolitiche Vallesane (Versoyen) e Piemontesi, e da varie unità austroalpine esterne (Dent Blanche s.l.) ed interne (Sesia-Lanzo), riferibili al margine continentale adriatico. Le unità esterne si suddividono in lembi superiori, in fades scisti blu di età cretacica, e in lembi inferiori, in facies eclogitica di età eocenica inf-media, analoga a quella delle ofioliti circostanti. Verso la fine della sua esumazione, il prisma orogenico ha subito una sovraimpronta metamorfica in fades scisti verdi dell'Eocene sup.-Oligocene inf. e, nell'Oligocene, è stato intruso da filoni di andesiti e lamprofiri e vene di quarzo aurifero. La struttura profonda della Valle d'Aosta e del contiguo Vallese è ricostruibile in base all'interpretazione geologica delle immagini sismiche prodotte dagliesperimenti CROP-ECORS e NFP 20, Esse confermano la struttura asimmetrica della catena, con le unità di origine adriatica (africana) al di sopra di quelle europee
Geological outline of the Alps
No full textThe Alps were developed from the Cretaceous onwards
by subduction of a Mesozoic ocean and collision between the Adriatic (Austroalpine-Southalpine) and European (Penninic-Helvetic) continental margins.
The Austroalpine-Penninic wedge is the core of the
collisional belt, a fossil subduction complex which floats
on the European lower plate. It consists of continental
and minor oceanic nappes and is marked by a
blueschist-to-eclogite-facies imprint of Cretaceous-
Eocene age, followed by a Barrovian overprint. The
collisional wedge was later accreted by the Helvetic
basement and cover units and indented by the Southalpine lithosphere, which in turn was deformed as an antithetic fold-and-thrust belt
Le lettere di Felice Giordano a Quintino Sella. Parte prima (9.8.1847-13.5.1859) - The Correspondence between Felice Giordano and Quintino Sella. First Part (Summer 1847 - Spring 1859)
No full textIn this study 81 letters sent by Felice Giordano (1825-1892) to his friend Quintino Sella (1827-1884) between summer 1847 and spring 1859 are transcribed and annotated. Giordano and Sella had both graduated in hydraulic engineering (1847) at the University of Turin and later specialized at the École des Mines in Paris and European mines and modern metallurgical industries. Back to Turin, Giordano was applicated to the Royal Corps of Mines and sent to Cagliari (1852) as a regent of the Sardinian Mining District. The first letters refer to the period they spent together in France and the other ones to the seven years of intense activity given by Giordano in Sardinia, carefully visiting mines and mineral deposits, as well as operating with the need to attract foreign capital and avoid easy speculations. Interesting aspects emerge about the personal relationships between Giordano and Sella, their scientific collaboration and the history and perspectives of mining in Sardinia
Le lettere di Felice Giordano a Quintino Sella. Parte seconda (7.1859-3.5.1875) - The Correspondence between Felice Giordano and Quintino Sella. Second Part (7.1859-3.5.1875)
No full textFelice Giordano (1825-1892), a piedmontese hydraulic engineer and mining specialist, was a fellow student and a faithful friend of Quintino Sella (1827-1884), both graduated at the University of Turin, upgraded at the École des Mines in Paris and were then recruited by the Royal Corps of Mines of the Sardinia Kingdom. Giordano's life, free of family ties, was devoted full time to institutions, field research, mountaineering and adventure, with a view to implementing the projects and requests of Quintino unable to share field work, burdened as he was by his high political and ministerial role. The correspondence sent by Felice Giordano to Quintino Sella covers a period of 37 years, from 1847 to 1884. A first group of 81 letters have been transcribed, commented and published within a project promoted by the History Studies Center of the University of Turin, mainly referring to Giordano’s stay in Sardinia as director of the local mining district. Back to Turin and promoted to chief engineer, Giordano was in charge of the Inspectorate of the Italian Royal Corps of Mines, first in Turin until 1868, then in Florence, the temporary capital, and from 1871 definitively in Rome, where he subsequently became director of the Geological Survey: the newly founded Servizio Geologico d’Italia” aimed at creaing the geological map of Italy, the “great enterprise” conceived by Quintino Sella. The present study deals with a second group of 71 letters exchanged by Giordano and Sella between 1859 and 1875. These letters besides attesting the strong friendship that bound Felice and Quintino, not only in the professional field, but also in the sphere of personal events and affections, deal with two main themes: i) the onerous duties of office, carried out either at headquarters or with frequent missions to evaluate the mining and industrial activities of the newborn Kingdom of Italy, from the Alps to Sicily, and to point out functions, problems and needs of the Royal Corps of Mines; ii) the mountaineering feats, from the ascent of Mont Blanc (1864) to the lost competition for the conquest of the Matterhorn (1865), followed by an epic assault failed due to bad weather (1866), up to the “revenge” of the personal ascent (1868) performed with the main objective of describing step-bystep the geology of the Gran Becca. The last five letters refer to the adventurous journey around the world that Giordano made from 1872 to 1876 on confidential assignment to explore the ‘Far East’ and to look for suitable places to establish penitential colonies and activate new commercial relationships, concluding with a negative evaluation. These amazing activities were always carried out with strictness, the technical competence of the engineer-geologist, the curiosity of the scientist and the spirit of service that distinguished his entire life. All that with his unassuming way – belittling his successes – that Quintino friendly reproached
The Aosta-ranzola extensional fault system and Oligocene-Present evolution of the Austroalpine-Penninic wedge in the northwestern Alps
No full textPost-nappe brittle structures across the Austroalpine-Penninic wedge are representative of two principal deformation stages. The former (D1) developed during the Late Oligocene, the latter (D2) from the Miocene to the Present. Major D1 features are the E-W Aosta-Ranzola half-graben and the NE-SW Ospizio Sottile subvertical normal fault system. Oligocene extension was also characterized by hydrothermal activity and intrusion of calc-alkaline to ultra-potassic dikes. From the Miocene onwards (D2), the Ospizio Sottile system was re-activated as a SE sinistral boundary of the Pennine-Graian Alps block of nappes, bodily moving away from the Simplon detachment to the SW. Inside the escaping block, a number of D2 slightly diverging sublatitudinal splays (Aosta-Piccolo San Bernardo system) was generated, as well as a regular set of NW-trending normal faults from the Simplon to the Gran Paradiso massif. Instead, the Aosta-Ranzola system was poorly reworked in that time. More generally, the short-lived Oligocene extension (D1) was associated to slab break-off of lower plate, wedge rebound, rapid uplift and thermal perturbation. From the Early Miocene onwards the Oligocene extension was replaced by renewed compression, allowing the vertical extrusion of the Lepontine dome and lateral escape of the overlying Pennine-Graian Alps block
3D fold and fault reconstruction with an uncertainty model: An example from an Alpine tunnel case study
No full textIn order to improve the railway connection between Austria and Italy, a base tunnel, extending from Fortezza to
Innsbruck (57 km), is under study. The design corridor crosscuts a large and strongly tectonized section of the Eastern Alpine chain, characterized by complex metamorphic and igneous lithology and polyphase structures developed under ductile to brittle deformation conditions. In order to model the sub-surface geology of the area, surface and sub-surface geological data have been integrated in a spatial database. 3D geological models of the Italian part of the corridor have been constructed on the basis of this data using two approaches. The first is a more traditional approach, involving the reconstruction of several parallel and intersecting cross-sections. It has been implemented using ArcGISs software with custom-developed scripts that enable one to automatically project structural data, collected at the surface and along boreholes, onto cross-sections. The projection direction can be controlled and is based on structural trends obtained from a detailed statistical analysis of orientation data. Other ArcGISs scripts enable linking of the network of crosscutting profiles and help to secure their consistency. The second approach involves the compilation of a true 3D geological model in gOcads. As far as time efficiency and visualization are concerned, the second approach is more powerful. The basic structural geology assumptions, however, are similar to those applied in the first approach. In addition to the 3D model,
compilation scripts (ArcGISs and gOcads) have been developed, which allow estimation of the uncertainties in the depth extrapolation of structures observed at the surface or along boreholes. These scripts permit the assignment of each
projected structural element (i.e., geological boundaries, faults and shear zones) to a parameter estimating reliability. Basic
differences between ‘‘data-driven’’ interpolation and ‘‘knowledge-based’’ extrapolation of geological features at depth are also discussed and consequences for the uncertainty estimates of 3D geological models are evaluated
Carta Geologica e note illustrative del transetto val di Vizze-Fortezza (Alpi Orientali)
No full textNell'ambito delle indagini geologiche realizzate per la progettazione della galleria ferroviaria di base
del Brennero (Brenner Basistunnel), abbiamo eseguito nel 2000-01 il rilievo geologico-strutturale alla Scala 1:10.000
del corridoio compreso tra l'lsarco, la Val di Vizze (Vipiteno), la Val di Valles e Fortezza. II rilievo è stato generalizzato e ridotto alla Scala 1:25.000 nella carta allegata, che comprende la parte interna del prisma collisionale austroalpino-pennidico, il Lineamento Periadriatico e il basamento cristallino delle Alpi Meridionali. Le unità pennidiche appartengono all'involucro esterno e intermedio dell'antiforme meridionale (Gran Veneziano-Zillertal) esposta nel settore sud-occidentale della Finestra del Tauri. Esse sono costituite dalle sequenze oceaniche dei calcescisti con ofioliti della Falda del Glockner e dai metasedimenti clastici di margine continentale della sottostante Unità di Tulver-
Senges, di probabile età permo-eotriassica, affioranti nelle omonime piccole finestre tettoniche. L'Austroalpino affiorante a sud della finestra è costituito da un basamento polimetamorfico (Complesso Mules-Merano) e da limitate
coperture permo-triassiche. II contatto tettonico tra Austroalpino e Sudalpino è marcato dalle linee della Pusteria e di Sprechenstein-Val di Mules (Lineamento Periadriatico) e dall'intrusione della Lamella tonalitica di Mules, di età
oligocenica. Allo stesso ciclo magmatico sono riferibili alcuni filoni dacitico-andesitici intrusi nel basamento austroalpino e nei calcescisti mesozoici. II basamento sudalpino è costituito dal plutone granitico-granodioritico di Bressanone, di età tardo-paleozoica, e dalle filladi incassanti. Le unità pennidiche sono dominate da un metamorfismo
collisionale di età terziaria, al limite tra la facies anfibolitica e quella scisti verdi. II basamento austroalpino mostra una impronta metamorfica varisica in facies anfibolitica e una parziale sovraimpronta di età cretacica. Queste unità sono deformate da tre principali fasi di piegamento duttile di età alpina, seguite da deformazioni fragili-duttili e fragili, prevalentemente di tipo distensivo e trascorrente. II granito di Bressanone mostra solo deformazioni fragili.
L'antiforme delle unità austroalpine e pennidiche è dislocata da quattro principali sistemi di faglie: i) il sistema diretto NNE-SSW (orizzonte deformativo del Brennero), dominante a scala regionale e responsabile della scomparsa, nell'area della carta, di buona parte delle unità continentali esposte nell'antiforme Gran Veneziano-Zillertal; ii) il sistema ENE-WSW, presente nel prisma austroalpino-penninico e nel granito di Bressanone; iii) il sistema E-W, concentrato soprattutto nella fascia di deformazione associata alla Linea della Pusteria; iv) il sistema WNW-ESE, ben rappresentato dalla Linea Sprechenstein-Valle di Mules e presente anche nel granito di Bressanone. Molti di questi sistemi di faglie sono caratterizzati da spessi orizzonti di cataclasiti e gouge argillosi
Carta Geologica d’Italia alla scala 1:50.000 (Geological Map of Italy, 1:50.000 scale): foglio 91 Chatillon e Note illustrative
No full textStructural control on mass-movement evolution: A case study from the Vizze valley, Italian Eastern Alps
No full textA large post-glacial deep-seated mass movement is described from the area east of Vipiteno-Sterzing (Alto Adige-South Tyrol, Eastern Alps), mainly devloping in calcschists of the ophiolitic Glockner nappe (southen antiform of SW Tauren window). A close relationship exists between differential slope evolution, structural setting, and slope attitude. Lateral spread develops in an area where the dominant schistosity is subvertical and parallel to the slope, and is facilitated by dissolution of evaporite-bearing bodies. Sackung develops in an area with low-angle schistosity and NNE-SSW high angle faults, parallel to the ridge segment. A huge rock-fall was set off the intersection of the steep N-Dipping schistosity with E-W and N-S to NNE-SSW fault and joints. As a whole, the deep-seated gravitational slope deformation (DSGSD) is an outstanding example of how the mechanics of large mass movements and their potential evolution are controlled by the structural framework, which is the ultimate result of a complex tectonic history
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