A vestige of very high-pressure (ca. 28 kbar) metamorphism in the Variscan Bohemian Massif, Czech Republic
Kotková, Jana; Harley, Simon L.; Fišera, Milan
European Journal of Mineralogy Volume 9 Number 5 (1997), p. 1017 - 1034
published: Sep 24, 1997
manuscript accepted: Mar 17, 1997
manuscript received: Jul 12, 1996
ArtNo. ESP147050905010, Price: 29.00 €
Abstract A unique Mg-Al rich rock from the Podolsko Complex of the South Bohemian Moldanubicum contains a relic assemblage of pyrope-rich garnet + low-Al orthopyroxene + quartz that implies very high-pressure (VHP) conditions of metamorphism. Primary garnet (70 mol% Prp; XMg = 0.70-0.73, Grs 30 kbar pressure estimates obtained on mantle-derived garnet peridotites and garnet pyroxenites, as well as eclogites with reported occurrence of palisade quartz after coesite in the Saxothuringian Zone. It remains uncertain whether the lower pressure (< 10 kbar) granulite-facies overprint recorded in the reaction textures reflects simple decompression, with higher-pressure reactions impeded by sluggish kinetics, or the effects of a distinct heating event superimposed on the VHT assemblage subsequent to decompression.