^a Department of Geology and Geophysics, University of Wisconsin-Madison, Madison, WI 53706, USA

^b Department of Geosciences, University of Arizona, Tucson, AZ 85719, USA

^c Department of Geology and Geophysics, University of Calgary, Calgary, Alberta, Canada T2N 1N4

^d Geological Institute of Romania, RO-78344, Bucharest 32, Romania

A prograde history for many HP metamorphic rocks is documented by the presence of lower pressure mineral inclusions and compositional zoning in garnet. Application of commonly accepted thermobarometers to eclogite (grt+cpx±ky±phn±pg±zo) yields a range in “peak” pressures and temperatures of 10.8–22.3 kbar and 545–745 °C, depending on tectonostratigraphic unit and locality. Zoisite equilibria indicate that activity of H₂O in some samples was substantially reduced, ca. 0.1–0.4. HP granulite (grt+cpx+hb+pl) and HP amphibolite (grt+hbl+pl) may have formed by retrogression of eclogites during high-temperature decompression. Two types of garnet peridotite have been recognized, one forming from spinel peridotite at ca. 1150–1300 °C, 25.8–29.0 kbar, and another from plagioclase peridotite at 560 °C, 16.1 kbar.

The Variscan evolution of the pre-Mesozoic basement in the South Carpathians is similar to that in other segments of the European Variscides, including widespread HP metamorphism, in which P–T–t characteristics are specific to individual tectonostratigraphic units, the presence of diverse types of garnet peridotite, diachronous subduction and accretion, nappe assembly in pre-Westphalian time due to collision of Laurussia, Gondwana, and amalgamated terranes, and finally, rapid exhumation, cooling, and deposition of eroded debris in Westphalian to Permian sedimentary basins.