Original paper

Eclogite-facies metamorphism at the eastern margin of the Bohemian Massif subduction prior to continental underthrusting?

Konopásek, Jiří Schulmann; Johan, Věra

Abstract

In garnetiferous micaschists occurring at the northern termination of the Moravian domain, metabasites were found containing relics of eclogite-facies assemblages. In these rocks, minimum pressure conditions of 13 kbar at temperatures of 625-655 °C were followed by decompression to amphibolite-facies conditions. Surrounding metapelites contain Fe-rich chloritoid and Fe-rich staurolite preservedas inclusions in garnet porphyroblasts indicating early PT conditions of 570 °C at pressures of 6-7 kbar.The matrix assemblage shows an increase of temperature and pressure to about 615 °C at 6.5-9 kbar.The PT paths of both metapelite and amphibolitized eclogite are suggested to converge at the peak temperature conditions of the metasediments. The PT evolution of the eclogitic sample and of the surrounding metapelites is different from the PT history of the same rocks occurring in the Moldanubian domain but similar to that of the Moravian metasediments. Thus, the presence of eclogite-facies metamorphism at the eastern margin of the Bohemian massif suggests early subduction and subsequent collision of the Brunovistulian foreland with the internal Variscan orogenic root domain.

Keywords

eclogitemetapelitept conditionsmoravian domainbohemian massif