High pressure transormations of pyrope (garnet) and pyrope (pyroxene)

Abstract

Clinopyroxenes with higher contents of calcium and alumina in pyroxenites from inclusions in serpentinites of the central part of the granulite complex near Waldheim/Saxony contains several different exsolutions as producte of diffusive transformations under high pressures. The interpretation of the chemical composition of the exsolutions and the pyroxene host in application to the Published thermobarometers in the CMAS-system shows very different values between 685–1400°C temperature and 8 to above 30 kbar pressure, indicating a polymetamorphic high pressure history of the pyroxenites. The partial transformation of the pyrope (garnet) to pyrope (pyroxene) is strong kinetic influenced.

Key Words:

• Pyroxene
• garnet
• high pressure transformation