New insights into the building of the Variscan Belt in Eastern Europe (Romania, Serbia, Bulgaria)
Published:April 17, 2019
Gaëlle Plissart, Hervé Diot, Christophe Monnier, Marcel Mărunţiu, 2019. "New insights into the building of the Variscan Belt in Eastern Europe (Romania, Serbia, Bulgaria)", Metamorphic Geology: Microscale to Mountain Belts, Silvio Ferrero, Pierre Lanari, Philippe Goncalves, Eugene G. Grosch
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The basement of the Alpine Upper Danubian/Balkan nappe, dismembered between Romania, Serbia and Bulgaria, contains evidence of the Variscan orogenic evolution (Lower Devonian Balkan–Carpathian ophiolite, Carboniferous granites). Our study presents a new tectono-metamorphic interpretation of this basement and documents two main deformation phases, D1 and D2. D1 is a right-lateral thrust recorded in the metagabbroic rocks at the base of the ophiolitic nappe that also affects the underlying units. This phase is related to the ophiolite emplacement on a northerly margin with a top-to-the-palaeo-WNW (Variscan coordinates) at c. 360 Ma. D2 records a collisional event in a sinistral transpressive regime. In a zone of sheared folds, it juxtaposed low- (Eşelniţa metasediments) to high-grade metamorphic rocks (Corbu rocks: 600°C/ 5.2 kbar). Syntectonic granitic intrusions later heated these rocks locally before their final cooling, still during the D2 phase, and with localized circulation of fluids. The sinistral transpressive regime would prevail after the docking of the Balkans and the Sredna Gora terranes separating the Balkan–Carpathian oceanic basin and could correspond to left-lateral escape due to large-scale readjustments between both terranes during the Carboniferous. The Upper Danubian/Balkan basement appears to be located more northerly in the Variscan Belt than the other intra-Alpine basements (Getic, Western Carpathians, Eastern Alps, Western Alps).
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Metamorphic Geology: Microscale to Mountain Belts
CONTAINS OPEN ACCESS
In Earth evolution, mountain belts are the loci of crustal growth, reworking and recycling. These crustal-scale processes are unravelled through microscale investigations of textures and mineral assemblages of metamorphic rocks. Multiple episodes of metamorphism, re-equilibration and deformation, however, generally produce a complex and tightly interwoven pattern of microstructures and assemblages. Over the last two decades, the combination of advanced computing and technological capabilities with new concepts has provided a vast array of novel petrological tools and high-resolution/high-sensitivity techniques for microanalysis and imaging. Such novel approaches are proving fundamental to untangling the enigma represented by metamorphism with an unprecedented level of detail and confidence. As a result, the first decade and a half of this century has already seen the tumultuous development of new research avenues in metamorphic petrology. This book aims to provide a timely overview of the state of the art of this field, of newly developed petrological techniques, future advancements and significant new case studies.