Amphibolites and granulites from Lutomia, Góry Sowie (Owls Mts)

Abstract

High grade rock research is an important element in the study of processes taking place at great depths. This study is focused on retrogressive metamorphism in granulites and amphibolites outcrops in Góry Sowie (Bochemian Massif). The aim of this work is to perform complex petrographic and petrological research using microscopic methods and chemical analysis with the electron microprobe. Petrographic and petrological evidences concluded that the rock protholit was strongly enriched in Ca, Ti and saturated by water. Additionally the protholit of the studied rock was a high pressure, high temperature rock, from the border of the stability field eclogite and granulite facies, which as a result of late metamorphic processes were partly transformed into lower-pressure granulites and amphibolites. On the basis of mineral structures and paragenesis, four metamorphism stages were distinguished for felsic granulites, such as: eclogite facies (M1), retrogressive clinopyroxene (M2), retrogressive amphibole (M3), secondary minerals (M4) and for mafic granulites: stage without plagioclase (eclogite facies?) (M1), granulite facies (M2), amphibole facies (M3), secondary mineral (M4).