The evolution of perpendicular linear fabrics in synkinematically emplaced tourmaline granite (central moravia-bohemian massif)

Melka, Radek; Schulmann, Karel; Schulmannova, Barbora; Hrouda, František; Lobkowicz, Michal

doi:10.1016/0191-8141(92)90160-x

Cited by 14 publications

(10 citation statements)

References 33 publications

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“…In the southern parts of the Svratka and Moldanubian allochthonous units, however northeast-oriented less intense mineral lineations appear. MELKA et al (1990) suggest that both lineations developed during a complex thrust-wrench D1 regime where the southwest-trending lineation originated during the D1 northeastward thrusting period, and the northwest-trending lineation corresponds to the north-westward tectonic escape along early lateral ramp parallel to the border of Moravian nappes.…”

Section: Tectonic Evolutionmentioning

confidence: 94%

“…The dominant subhorizontal northwest-trending stretching lineation, in places connected with L>>S fabrics exhibits northwestoriented shearing. Recumbent folds showing variable dips of axial planes are mostly parallel to the northwest-trending stretching lineation (Kt~-mCm4L, 1984;MELKA et al, 1990).…”

Section: The Southernmost Part Of the Svratka Allochthonous Unitmentioning

confidence: 99%

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Evolution of nappes in the eastern margin of the Bohemian Massif: a kinematic interpretation

et al. 1991

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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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Section: Tectonic Evolutionmentioning

confidence: 94%

Section: The Southernmost Part Of the Svratka Allochthonous Unitmentioning

confidence: 99%

Evolution of nappes in the eastern margin of the Bohemian Massif: a kinematic interpretation

et al. 1991

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“…7 in Willis, 1977); (3) formation of perpendicular lineations as a result of combined simple shearing and coaxial flattening with unequal principal extensions within the shear plane (Schulmann, Ježek & Venera, 1997, fig. 9); (4) formation of multiple lineations due to the progressive switch of lineation orientation during transpressional deformation as a result of increasing finite strain or convergence angle (Melka et al 1992;Parry et al 1997; see also details and fig. 5 in Tikoff & Greene, 1997).…”

Section: Multiple Magmatic Fabrics: What Are the Likely Fabric-forminmentioning

confidence: 99%

Multiple magmatic fabrics in plutons: an overlooked tool for exploring interactions between magmatic processes and regional deformation?

2008

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This paper elaborates on the concept of multiple magmatic fabrics in plutons. After a general overview of various types of multiple fabrics that may develop in magmatic rocks, two case examples of porphyritic granite and melasyenite plutons in the Bohemian Massif are examined. In the Jizera granite, complex variations in K-feldspar phenocryst shape-fabric revealed by image analysis of a 200 m long section of an underground tunnel are in contrast with homogeneously oriented magnetic (AMS) fabric carried by coaxial contributions of biotite, magnetite and maghemite. In the Knížecí Stolec melasyenite pluton, emplacement-related margin-parallel feldspar foliation was overprinted by flat-lying foliation; the latter is interpreted to record regional tectonic strain. At the two stations examined in detail, the crystallographic-preferred orientation of biotite and amphibole in the inter-phenocryst matrix (measured using electron back-scatter diffraction – EBSD) differed from both feldspar fabric and also from the AMS principal directions. Multiple magmatic fabrics in these two plutons are interpreted in terms of fabric superposition, where late weak strain is superposed onto a high-strength phenocryst framework, but is accommodated preferentially by small mineral grains (biotite, magnetite) in the melt-bearing matrix. This mechanism may explain the discrepancy between mesoscopic feldspar fabric and AMS. We conclude that multiple magmatic fabrics in plutons may thus result from accumulated strain caused by different processes during final crystallization and, as such, may serve as a sensitive indicator of the evolving interactions between magmatic and tectonic processes in the Earth's crust.

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“…In spite of a relatively small number of grains measured, between 35 and 110 ( Fig. Evidence from natural tectonites , Gapais and Barbarin 1986, Melka et al 1992 indicate activity of prism [c] slip as characteristic of very high temperature, near the granite solidus. The quartz grains have lobate boundaries and commonly exhibit cross-hatched undulatory extinction with sub grain boundaries parallel and perpendicular to the foliation trace.…”

Section: Quartz C-axis Fabricmentioning

confidence: 99%

“…The effects of the incremental deformation within flowing fluids on the rotation of suspended rigid bodies present a different problem (Owens, 1973;Marre, 1986, p. 13-25;Melka et al, 1992). The effects of the incremental deformation within flowing fluids on the rotation of suspended rigid bodies present a different problem (Owens, 1973;Marre, 1986, p. 13-25;Melka et al, 1992).…”

Section: Internal Deformation Due To Buoy Ant Diapirism: Tiieorymentioning

confidence: 99%

Granite: From Segregation of Melt to Emplacement Fabrics

Bouchez¹,

Hutton²,

Stephens³

1997

Petrology and Structural Geology

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The evolution of perpendicular linear fabrics in synkinematically emplaced tourmaline granite (central moravia-bohemian massif)

Cited by 14 publications

References 33 publications

Evolution of nappes in the eastern margin of the Bohemian Massif: a kinematic interpretation

Evolution of nappes in the eastern margin of the Bohemian Massif: a kinematic interpretation

Multiple magmatic fabrics in plutons: an overlooked tool for exploring interactions between magmatic processes and regional deformation?

Granite: From Segregation of Melt to Emplacement Fabrics

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