Origin of felsic granulite microstructure by heterogeneous decomposition of alkali feldspar and extreme weakening of orogenic lower crust during the Variscan orogeny

0357499 - GFÚ 2011 RIV GB eng J - Journal Article
Franěk, J. - Schulmann, K. - Lexa, O. - Ulrich, Stanislav - Štípská, P. - Haloda, J. - Týcová, P.
Origin of felsic granulite microstructure by heterogeneous decomposition of alkali feldspar and extreme weakening of orogenic lower crust during the Variscan orogeny.
Journal of Metamorphic Geology. Roč. 29, č. 1 (2011), s. 103-130. ISSN 0263-4929. E-ISSN 1525-1314
R&D Projects: GA ČR GA205/09/0539
Grant - others:GA ČR(CZ) GA205/05/2187
Institutional research plan: CEZ:AV0Z30120515
Keywords : felsic granulites * Moldanubian domain * quantitative microstructural analysis * quartz and feldspar rheology * Variscan belt
Subject RIV: DB - Geology ; Mineralogy
Impact factor: 2.990, year: 2011

This study answers the question of origin and evolution of a granulitic microstructure typically developed in felsic granulites of the European Variscan belt. It shows that the precursor of the Variscan felsic granulites was a high-pressure alkali feldspar-rich coarse-grained layered orthogneiss. Its S1 subhorizontal layering is defined by the alignment of alkali feldspar porphyroclasts alternating with monomineralic bands of quartz and bands rich in plagioclase and garnet. The alkali feldspar porphyroclasts contain inclusions of quartz, garnet, kyanite, biotite and rutile, reflecting peak P–T conditions of 1.6–1.8 GPa and 850 °C during S1 formation.
Permanent Link: http://hdl.handle.net/11104/0195763