1,720,996 research outputs found
Contractional and transcurrent tectonics in the Marmolada Group (Dolomites, Italy)
No full textThe Marmolada Massif (Southern Alps) consists of sedimentary successions ranging in age from the Late Permian to the late Middle Triassic. These successions are involved in a complex polyphase Alpine deformation, which is apparently stronger here than in the surrounding areas. Integrated stratigraphic and structural analyses, based on a detailed 1:10,000 geological mapping, were performed. The Upper Permian shows evaporitic sulphates, that acted as the major detachment level, during the Alpine deformation. The Middle Triassic was characterised by tectonic uplift, followed by accelerated subsidence, that controlled the development of subtidal carbonate platforms (Contrin Fm) and of elongated basins, followed by the aggradation of three independent buildups (Marmolada, Vernel and Ombrettola), surrounded by deep water basins. A nice example of platform-top to slope section is visible at the Marmolada Glacier front. The platform-top is very rich in subtidal calcarenites, punctuated by emersion surfaces. The wave resistant reef was very rich in automicritic crusts and marine cements, while the huge slope deposits show nice clinostratifications. The Ladinian was characterised by a short lived magmatic episode, with high-K calc-alcaline to shoshonitic affinity. In the Marmolada area, at least two main Alpine tectonic phases have been recognised. The first phase, which is certainly the more important in terms of deformation, is characterised by low- to middle-angle contractional faults, associated with important shortening. The northern Marmolada and Vernel Platforms overthrusted the southern Ombrettola Platform and the slope clinostratifications were often activated as reverse faults. Kinematic indicators on the principal structures document a vergence variability between SSE and SSW, probably related to the mechanical anisotropies of the stratigraphic cover or to two possible subevents. North-verging back-thrusting planes have also been discovered. For comparison with other sectors of the Southern Alps, the age of the major shortening is probably Oligo-Miocene. The second phase is characterised by high-angle mainly strike-slip faults, which partly dismembered the older low-angle structures. Particularly important is the shear zone developed along the northern slope of the Contrin and Ombrettola Valleys, changing in direction from WNW-ESE to W-E. This phase is probably Late Messinian-Pliocene in age and strongly influences the present-day landscape
New occurrence of deerite in the western Alps
No full textDeerite has been found in the Cu-Fe sulfide deposit of Viafiorcia, Western Alps, associated with the Piemonte ophiolite nappe. This hydrous, ferrous, ferric silicate occurs together with Na-amphibole, stilpnomelane+/- white mica, albite and carbonate, and with pyrite, chalcopyrite, bornite, pyrrothite, magnetite +/- sphalerite, mackinawite, linneite, tennantite, chalcocite, digenite and covellite within a post-Triassic silica-rich deposit above a flattened lens of metagabbro and minor serpentinite which is interbedded in the calcschist sequence. This Cu-Fe-Si deposit is believed to have formed by precipitation from a hydrothermal system occurring in the extensional Piemonte margin. Electron microprobe analyses (three points) of deerite yield the following structural formula:
(Mg0.87Fe2+ 11.23Mn0.15)12.25(Fe3+5.95Al0.18)6.13Si11.72O39.78(OH)10.2
Ofioliti Special Section "Late Variscan to Alpine orogenic evolution: the role of rift inheritance", Foreword
No full text3D 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
Gear diagnostic: Experimental data comparison of radial accelerometers, tangential accelerometers and torquemeter
No full textIndustry 4.0 is the next step of the evolution of future companies in order to improve efficiency sustainability and performances. With a view to industry 4.0 and to improve the efficiency of gear transmission a measurement campaign has been performed comparing four gear pair with different surface treatment, damages and coating The experimental results on the measurement of radial accelerometers, tangential accelerometers and torque-meter measurement of spur gears rig with surface coatings, advanced pitting with a crack and damaged gears are presented and analysed with Time Synchronous Averaged (TSA) method and results are explained, comparing the effectiveness of the different sensors used to monitor the system under investigation
Evolution history of Austroalpine Basement and associated mantle peridotites in the Ulten Zone, Italian Eastern Alps
No full textThe mafic boudins of the southern Furgg Zone, Monte Rosa Nappe, NW Italy: From tholeiitic continental basalts to alpine eclogites and retrogressed products
No full textIl settore occidentale dell’unità di Inda Ad ed il granito di Arar (Somalia settentrionale)
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