ZusammenfassungDer Deckenbau am Ostrand der B6hmischen Masse erfolgte in zwei aufeinanderfolgenden Stadien, die sich sowohl in ihrer Kinematik als auch in ihrer Metamorphoseentwicklung deutlich voneinander unterschieden.Die
AbstractThe entire pile of nappes in the eastern margin of the Bohemian massif is characterized by two stages of Variscan nappe emplacement each exhibiting a different kinematic and metamorphic evolution.The older emplacement (D1) probably occurred around 350-340 Ma ago and was synmetamorphic. The nappes show a typical systematic superposition of higher grade metamorphic units over lower grade ones. Thus, the crystalline complexes showing a HT-MP Barrovian imprint (Svratka allochthonous unit and Moldanubicum) were thrust over an intermediate unit affected by MT-MP recrystallization (Bfteg orthogneiss and its country rock), and at the base of the D1 nappe pile the Inner Phyllite Nappe (Bfl 3) Potok Unit) is characterized by LT/LP metamorphism.The second stage of tectonic evolution (D2) is characterized by a thin-skinned northward-oriented nappe emplacement that occurred under LT-LP conditions dated at 320-310 Ma. The whole nappe sequence formed during the first tectonometamor- phic period (D1) was transported northward over the autochthonous >>Deblin polymetamorphic and granitic complex<< of Upper Proterozoic age and its Devonian sedimentary cover with very low metamorphism. During this second tectonic event the Brno granite massif (580 Ma) was only marginally incorporated in the Variscan nappe tectonics which resulted in kilometer-scale cover and basement duplexes. The tectonic evolution of the nappe pile ended with stage D3, represented by large-to medium-scale east-vergent folds with limited displacement.
R6sum6Uempilement des nappes a la bordure orientale du Massif de BohSme est caractrris6 par deux stades de mise en place prrsentant diffrrentes 6volutions cinrmatiques et mrtamorphiques.La tectonique majeure de mise en place des nappes crustales intervient lors d'un mdtamorphisme de type barrowien, cal6 autour de 350-340 Ma. Uempilement qui en rrsulte montre une superposition systrmatique d'unitds ~t fort degr6 de mrtamorphisme sur des unitds moins mrtamorphiques. Ainsi les complexes cristallins, montrant des reliques de mrtamorphisme de haute h moyenne pression-haute temprrature (unitrs cristallines de Svratka et du Moldanubien), chevauchent une unit6 intermrdiaire affectre par un mdtamorphisme de moyenne h basse pression-moyenne temprrature (l'orthogneiss de Biteg et son encaissant). A la base de cette pile 6difire durant la tectonique D1, l'unit6 des phyllites internes (unit6 de Bfl3~ potok) est caractdrisde par un mrtamorphisme de basse trmperature-basse pression.Le second stade D2 de l'rvolution tectonique est caractrris6 par une tectonique pelliculaire h vergence nord datre h 320-310 Ma. Uempilement rrsultant de D1 est ainsi transport6 vers le nord, au dessus du complexe autochtone d'~ge protrrozoique suprrieur (groupe de Deblin) et sa couverture sddimentaire drvonienne trrs faibleme...
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