Very high-pressure (>4 GPa) eclogite associated with the Moldanubian Zone garnet peridotite (Nové Dvory, Czech Republic)

Equilibrium pressure-temperature (P-T) conditions were estimated for kyanite-bearing eclogite from Nové Dvory, Czech Republic, by using garnet-clinopyroxene thermometry and garnet-clinopyroxene-kyanite-coesite (or quartz) barometry. The estimated P-T conditions are 1050-1150°C, 4.5-4.9 GPa, which are mostly the same as previously estimated values for garnet peridotite from Nové Dvory (∼1100-1250°C, 5-6 GPa). Such very high-P conditions, which correspond to about 150-km depth, have been obtained for some garnet peridotites in the Gföhl Unit of the Bohemian Massif, but pressure conditions of eclogites associated with the garnet peridotites have not been so well constrained. This is the first substantial finding of eclogite that gives such very high-P conditions in the Gföhl Unit of the Bohemian Massif. The Gföhl Unit mainly consists of felsic granulite or migmatitic gneiss, but these rock types do not display high-P (> 2.5 GPa) evidence. It is unclear whether both the peridotite body and surrounding felsic rocks in the Gföhl Unit were buried to very deep levels, but at least some garnet peridotites and associated eclogites in the Gföhl Unit have ascended from about 150-km depth.