The Brunovistulian: Avalonian Precambrian sequence at the eastern end of the Central European Variscides?
Published:January 01, 2000
F. Finger, P. Hanžl, C. Pin, A. Von Quadt, H. P. Steyrer, 2000. "The Brunovistulian: Avalonian Precambrian sequence at the eastern end of the Central European Variscides?", Orogenic Processes: Quantification and Modelling in the Variscan Belt, Wolfgang Franke, Volker Haak, Onno Oncken, David Tanner
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An outline is presented of the present state of research on the Precambrian evolution history of the Brunovistulian, a large (30 000 km2), mainly sediment covered Peri-Gondwana basement block at the eastern end of the Central European Variscides. On the basis of recent chemical, isotopic and geochronological data it is argued that the eastern half of the Brunovistulian (Slavkov Terrane) originated in an island-arc environment, documenting the rare case of Neoproterozoic crustal growth in central Europe. The western half of the Brunovistulian, the Thaya Terrane, includes more mature, recycled cratonic material and is considered to have been originally part of the Neoproterozoic Gondwana continent margin. A phase of regional metamorphism at c. 600 Ma, followed by extensive granitoid plutonism, probably marks the stage when the Slavkov Terrane was accreted to the Thaya Terrane by arc–continent collision. A belt of metabasites, which is intercalated between the two terranes, may represent relics of the incipient arc or a back-arc basin. A comparison of geochronological data shows that the timing of geological events recorded in the Brunovistulian does not correlate with the evolution history of the Cadomian crust in the Teplá–Barrandian zone and the Saxo-Thuringian belt. This supports the theory that the Brunovistulian is not part of Armorica but derived from a different sector of the Neoproterozoic Gondwana margin. A correlation with the Avalonian superterrane appears feasible.
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Orogenic Processes: Quantification and Modelling in the Variscan Belt
Research into the orogenic processes that shaped the continental crust of Europe has a long-standing tradition. Why the need to quantify and model? It is not just satisfactory to identify subduction zones, accretionary prisms, island arcs, extensional collapse and other standard items of the geodynamic menu. Such interpretations need to be quantified: extent and composition of subducted crust, angle and speed of subduction, amount and composition olmelts produced, heat sources for metamorphism. All such interpretations have to conform to first principles, and also to stand the test of quantitative balancing – a concept first developed for the conservation of length or volume in tectonic cross sections. Also in other fields, the correlation of causes and effects and the internal consistency of dynamic models requires a numerical approach.
The present volume combines review articles with reports on recent progress in an attempt to address these aims. There is a foldout map of the region, which locates the main areas of outcrop and tectono-stratigraphic units, and a reassesment of the Palaeozoic time scale permits correlation of tectonic, metamorphic and magmatic events with the sedimentary record of the upper crust.