170,024 research outputs found
Medioevo Tedesco. Studi e testi
No full textCollana di testi e studi sul medioevo tedesco sotto l'aspetto letterario e linguistico. Ultimo volume (2004): Paolo Marelli, Sintassi e semantica dei casi nella Sächsische Weltchronik
Visualising lattice vibrations: new features of the UNISOFT-program
No full textThe lattice dynamical program package UNISOFT had been developed as a tool for phenomenological model calculations and optimisation of experiments on phonon dispersion in the mid-1980's. In this paper we present a new version of UNISOFT which provides a number of new features. (C) 2000 Elsevier Science B.V. All rights reserved
Structural setting of the Paleozoic crystalline basement of the Northern Apennines (Italy).
No full textStrike-slip geometry inferred from the seismicity of the Northern-Central Apennines (Italy)
No full textThe Relationships between the Internal Nappe Zone and the Regional Mylonitic Complex in the NE Variscan Sardinia (Italy): Insight from a New Possible Regional Interpretation?
No full textThis study presents an updated interpretation of geological data collected between 1984 and 2022. The area under consideration holds significant regional importance as it is located between the Internal Nappe Zone (INZ) and the Regional Mylonitic Complex (RMC). Re-evaluation of the geological data has highlighted a more intricate structural framework than what is currently documented in the existing literature. This paper aims to illustrate, through structural analysis, that the Posada Valley Shear Zone (PVSZ) does not serve as the transitional boundary between the Inner Nappe Zone and the Regional Mylonitic Complex or High-Grade Metamorphic Complex (HGMC) as traditionally thought. Instead, the authors’ findings indicate that the transition boundary is confined to a shear band with a variable thickness ranging from 10 to 70 m at its widest points. The development of the Posada Valley Shear Zone is characterized by a series of transitions from mylonite I S-C to mylonite II S-C, extending over approximately 5 km. The formation of the Posada Valley Shear Zone is chronologically confined between the development of the East Variscan Shear Zone (EVSZ) and the emplacement of the Late Variscan granites. The differing orientations of Sm and S3 observed in the mylonitic events of the Posada Valley Shear Zone and the Regional Mylonitic Complex, respectively, are likely attributable to an anticlockwise rotation of the shortening directions during the upper Carboniferous period. Furthermore, this study proposes that the Condensed Isogrades Zone (CIZ), despite its unclear formation mechanism, should be recognized as the true transition zone between the Inner Nappe Zone and the Regional Mylonitic Complex or High-Grade Metamorphic Complex. This new interpretation challenges the previously accepted notion of increasing Variscan metamorphic zonation toward the northeast. This conclusion is supported by the identification of the same NE–SW orientation of the D2 tectonic event in both the Old Gneiss Complex (OGC in the Regional Mylonitic Complex) and the lithologies of the Inner Nappe Zone and the Condensed Isogrades Zone. The comprehensive analysis and new insights provided in this paper contribute to a refined understanding of the geological relationships and processes within this region, offering significant implications for future geological studies and interpretations
Contact metamorphism in Middle Ordovician arc rocks (SW Sardinia, Italy): New paleogeographic constraints
No full textIn the early Cambrian Bithia Formation in the Variscan foreland of Sardinia, a Middle Ordovician granitic intrusion (478–457 Ma) is hosted by marly metasedimentary rocks that were affected by high-temperature (HT) metamorphism. A detailed structural–petrographical transect was conducted through the granitic intrusion and its host rocks. Field data and relationships between HT/low-pressure (LP) mineral assemblages in the metasedimentary rocks (Grt + Wo + Ves in carbonate lenses and And in pelite) demonstrate that the study area was affected by a polyphase HT overprint (I: T = 520–620 °C at XCO2 = 0.1, P: 0.2–0.4 GPa; and II: T = 600–670 °C at XCO2 = 0.1, P = 0.2–0.4 GPa) that pre-dates the Variscan tectonic, metamorphic, and igneous phases. In the Canigò or Canigou Massif (Eastern Pyrenees), the Somail Massif (Montagne Noire), and the Ruitor Massif (Internal Massifs, NW Alps), Middle Ordovician orthogneiss with relict igneous textures are deciphered despite being overprinted by Variscan amphibolite-to-granulite-facies metamorphism and subsequent Alpine low-grade metamorphism. Comparisons of associated igneous and metasedimentary rocks in the Sardinia foreland with the High-Grade Metamorphic Complex in the Variscan Axial Zone and the Canigou Massif indicate a convergent Middle Ordovician evolution that was overprinted by HT Variscan metamorphism
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