Ciśnienia i temperatury krystalizacji gabr Braszowic, blok przedsudecki.
Abstract
P-T conditions of Braszowice gabbro crystallization (Fore Sudetic Block, SW Poland)
The gabbroic rocks of Braszowice crystallized at moderate pressure of about 10-4 kb, i.e. at the depth of 30 -13 km. During their crystallization the rocks ascended together with the mantle in the conditions of a slow-spreading rift. Clinopyroxene crystallized in the temperature range of 1120 - 500°C, while amphibole-plagioclase pairs within an interval of 858 - 526°C. Water pressure was increasing together with amphibole crystallization conditioning generation of more basic plagioclases. At the subsolidus temperature of 765 - 500°C the gabbro minerals mainly underwent re-equilibration of the chemical composition and - in shear zones resulting from the uplift - also dynamic recrystallization.