High-grade metamorphic rocks in the pre-Alpine nappe stack of the Getic-Supragetic basement (Median Dacides, South Carpathians, Romania)

Metamorphic rocks in the pre-Alpine basement of the Getic-Supragetic units (Median Dacides of the Carpathian belt) are spatially related to different lithotectonic units, some of which contain high-pressure relicts reflecting an early stage of oceanic and continental subduction, locally synchronous with mylonitic shear zones. Kyanite-amphibole +/- quartz-bearing eclogites preserve a complete metamorphic clockwise loop; the estimated peak conditio ns within the outer part of the Cumpana unit were at least 20 kb at 780-860 degrees C. Pre-eclogite-stage magmatic phases occur in some units with tru e equilibrated eclogites. Clinopyroxene-plagioclase inclusions in garnet of a garnet-clinopyroxene assemblage within a metagabbro indicate a temperatu re around 760-790 degrees C at a maximum pressure of about 19 kb. The units finally evolved together during stages of exhumation under metamorphic con ditions ranging from the Barrovian-type (minimum age of 330 Ma) to the high -temperature/low-pressure type. The absolute age of the high-pressure stage and the eclogite protoliths is unknown. In comparison with other collision belts, it is likely that the gneiss units of the Median Dacides underwent a complete cycle of underthrusting and exhumation similar to other segments of the European Variscides, and that the formation of the eclogite occurre d during the early stages of subduction.